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Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original A

AABR

An acronym for Automated Auditory Brainstem Response the neural pathway to test hearing and other brainstem pathways.

abdomen

The body trunk between the diaphragm and the pelvis.

abdominal circumference

An ultrasound measurement of Abdominal Circumference (AC) is used to determine fetal age and normal development (small/large/abnormal) parameters. Measured at the outer edge of the circumference of the body plane in which the portal vein or stomach can be visualized in a tangential section. It is one of the four typical ultrasound assessments of fetal size and age: Biparietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL). Abdominal Circumference of less than 31 cm at 36 to 40 weeks gestation is a predictor of intrauterine growth retardation (IUGR).
(More? Ultrasound | Head Notes | Fetal Notes | Birth Notes | Intrauterine Growth Retardation)

abnormal spindle-like microcephaly-associated protein

A protein concentrated at mitotic spindle poles in embryonic neuroepithelial cells (progenitor cells of the brain) and down-regulated when they switch from proliferative to neurogenic divisions. Protein is associated with determining human cerebral cortical size, possibly by maintaining symmetric cleavage plane orientation in neuroepithelial cells during brain development.
(More? Neural Notes | Neural Abnormalities | OMIM ASPM | Fish JL, Kosodo Y, Enard W, Paabo S, Huttner WB. Aspm specifically maintains symmetric proliferative divisions of neuroepithelial cells. Proc Natl Acad Sci U S A. 2006 Jun 23)

abortion

The premature expulsion or loss of embryo, may be induced (medical) or spontaneous (miscarriage).

absolute risk

Term used in describing the effect of environmental teratogens on development. This epidemiological statistical term describes the high likely rate of occurrence of an abnormal phenotype among individuals exposed to the agent (e.g. fetal alcohol syndrome). The other risk descriptor term used to describe the likelyhood of an abnormality is relative risk.
(More? Abnormal Development - Environmental)

AC

Acronym for Abdominal Circumference.

acardiac twins

(acardia, twin reversed-arterial perfusion (TRAP) sequence, chorioangiopagus parasiticus) An extreme form of twin-twin transfusion syndrome. In a twinned human fetal development where monozygotic twinning or higher multiple births have an artery-to-artery and a vein-to-vein anastomosis in the monochorial placenta. The incidence is of 1% of monochorionic twin pregnancies (1 of 35,000 pregnancies).
(More? Twinning | Twin-twin transfusion syndrome )

acaricide

Acarida are a subclass of the athropods, ticks and mites. Chemicals used for killing or preventing ticks and mites in crops or animals. Some of the early chemicals (eg endosulphan) may have also had a suggested endocrine disruptor function.
(More? Endocrine Abnormalities)

accessory pancreatic duct

(APD) This duct also called Santorini's duct may be present as an anatomical variation due to the embryological origin of the pancreas from two pancreatic buds (dorsal and ventral). Note the main pancreatic duct (MPD) from the dorsal bud, present in the body and tail of the pancreas (also called Wirsung's duct).
(More? 2009 Lecture - Gastrointestinal Tract Development | Pancreas | Pancreas History)

acheiria

A limb abnormality with a missing hand or foot as described in the original classical classification of limb deficiencies.
(More? 2009 Lecture - Limb Development | Limb Abnormalities - Classification)

achondroplasia

Musculoskeletal defect of short limb skeletal dysplasia, due to a mutation in a dominant gene encoding fibroblast growth factor receptor-3 (FGFR3). Most common limb dysplasia, with shortened long bones (mainly proximal long bones) and is difficult to prenatally diagnose. Other mutaions of this gene cause milder skeletal dysplasia (hypochondroplasia) and a lethal skeletal dysplasia (thanatophoric dysplasia).
(More? Musculoskeletal Abnormalities | OMIM Achondroplasia | FGFR3)

acrocentric

Term used to describe chrompsomes which pair with a centromere located very close to one end giving a "V" shape rather than "X" of a central centromere pair. In the human, chromosomes 13,14,15,21 and 22 are acrocentric. In bovine all chromosomes are acrocentric.
(More? Endocrine Notes)

acrolein

A reactive aldehyde (conjugated Type-2 alkenes) formed as a product of lipid peroxidation in biological systems. Recently identified as a cigarette-related lung cancer agent
(More? Abnormal Development - Smoking | PNAS Article)

Acquired Immune Deficiency Syndrome (AIDS)

A fatal disease caused by a virus (human immunodeficiency virus, HIV) that destroys the immune system's ability to fight off infection. HIV virus is capable of being transmitted from mother to fetus.
(More? Abnormal Development - Viral Infection)

acrodynia

(Greek, acrodynia = painful extremities) chronic mercury poisoning in infants and young, also called "Pink Disease" occurred throughout the world (Australia 1890's) before the recognition of mercury's toxic effects. Mercurous chloride was used in "teething powders" which were given to crying babies as a purgative agent to cleanse the system.
(More? Heavy metals | Michigan Health MercurySpillFactsheet_85689_7.pdf)

acromegaly

Abnormality in the adult, overproduction of growth hormone causes bone thickening and cartilage growth.

acroplaxome

The sperm structure which forms the acrosome plate with intermediate filament bundles of the marginal ring at the leading edge of the acrosome.
(More? Spermatogenesis | Fertilization)

acrosin

A spermatazoa acrosomal protein has a role in fertilization including that of lysis of the zona pellucida (a serine protease) and in secondary zona pellucida (ZP) binding. Stored in mature spermatazoa as proacrosin.
(More? Spermatogenesis | Fertilization | OMIM Entry)

acrosome

The spermatazoa cellular structure containing a packet of enzymes located that allows it to dissolve a hole in the specialized extracellular matrix (zona pellucida, egg coat) surrounding the oocyte (egg). This enzymic digestion then allows the spermatazoa to penetrate and fertilize the egg. This structure is formed from the normal cellular organelle the Golgi apparatus.
(More? Spermatogenesis | Fertilization)

acrosome reaction

The chemical change that enables release of acrosomal contents and allow a sperm to penetrate an egg.
(More? Spermatogenesis | Fertilization)

activin A

(inhibin, erythroid differentiation factor) A transforming growth factor beta (TGFbeta) superfamily member which has roles in many different tissues. Acts through binding a number of activin receptors, transmembrane ser/thr kinase receptors. This protein is involved in the process of uterine endometrium development (decidualization) of human endometrial stromal cells following blastocyst implantation.
(More? Week 2 Notes | OMIM - inhibin)

adactyly

The absence of bones metacarpal or metatarsal leading to an absence of all digits as described in the original classical classification of limb deficiencies.
(More? Limb Abnormalities - Classification | Limb Abnormalities - Hand Classification)

ADAMTS-13

A blood metalloprotease found in plasma which cleaves [V.htm#VWF von Willebrand factor (VWF)] in the A2 domain at the Tyr-1605 -1606 bond.

adenine

(adenine triphosphate) One of the 4 types (ATCG) of nucleotides that make up DNA. Base pairs with thymidine by 2 hydrogen bonds.

adenohypophyseal placode

Specialised cranial surface ectoderm placode region that will form the endocrine anterior pituitary (adenohypophysis).
(More? Endocrine Development - Pituitary)

adenohypophysis

(anterior pituitary, pars distalis) The anterior part of the pituitary, which develops in the early embryo from the surface ectoderm adenohypophyseal placode. This placode will fold inward on the roof of the pharynx forming a transient structure Rathke's pouch, that looses its connection with the surface.
(More? Endocrine Development - Pituitary)

adenomatous rest

A kidney benign tumor developing from embryonic blastema cells. Blastema cells persist and under either genetic or epigenetic can change to become a neoplastic rest. These neoplastic rests can develop postnatally as a benign form (adenomatous rest) or a malignant Wilm's tumour form. The rests are further characterised by the time of generation leading to different anatomical kidney locations: early intralobar nephrogenic rests (within the renal lobe) and late pelilobar nephrogenic rests (periphery of the renal lobe).
(More? Wilm's tumour | nephrogenic rest | Urogenital Abnormalities | Urogenital Notes)

adenomyosis

(endometriosis interna, adenomyoma) A uterus disease involving infiltration (immediately adjacent to the endometrial cavity) of endometrial glands and stroma within the myometrium. Difficult to distinguish from leiomyoma.
(More? Reproductive System - Abnormalities | Medlineplus - adenomyosis)

adenovirus

A Class I virus containing a single double-stranded DNA (dsDNA), which can cause infections in the upper respiratory tract and gastrointestinal tract in many animals.
(More? Abnormal Development - Viral Infection)

adipocyte

The mature fat cell found in fat tissue and hypodermis layer of the skin.
(More? Musculoskeletal Development - Adipose | Endocrine Development - Adipose)

adipogenesis

The term used to describe the differentiation of preadipocytes into adipocytes.
(More? Musculoskeletal Development - Adipose | Endocrine Development - Adipose)

adipose

Fat, mesodermal in origin it is a type of connective tissue consisting mainly of adipocytes. The two forms of adipose are white and brown adipose tissue. Brown adipose is found in newborns (2 - 5 % of the body weight) and can be used to dissipate stored energy as heat (thermogenesis), while adults have mainly white adipose. Adipose tissue also has an endocrine function secreting the hormones leptin, adiponectin, and resistin.
(More? Musculoskeletal Development - Adipose | Endocrine Development - Adipose)

adontia

Term used to describe the total lack of tooth development.
(More? Integumentary Development - Tooth)

adnexa

(Latin, adnexae = appendages) Term used to describe any anatomical appendage (accessory structure, extension or outgrowth from the body). In reproductive anatomy used to describe appendages of the uterus "body"; ovaries, uterine tubes and uterus supporting ligaments.

adrenal gland

(suprarenal gland) The endocrine organ that anatomically sits on top of the kidneys (renal). It has two different embryonic origins, neurat crest (aderenal medulla) and mesoderm (adrenal cortex).
(More? Endocrine Notes - Adrenal Gland)

adrenal virilism

Abnormality that leads to the development of male secondary sexual characteristics in women with excessive adrenal gland activity.
(More? Endocrine Notes)

adventitia

Anatomical term describing the outermost connective tissue covering of any organ, vessel, or other structure not covered by a serosa. The covering is from the surrounding connective tissue and does not form an integral part of such organ or structure.

AFP

Acronym for Alpha-FetoProtein a protein detected in a prenatal diagnostic test.
(More? Alpha-FetoProtein)

after-birth

Term used to describe the delivery of placenta and placental membranes following birth of the child.

aganglionic colon

(intestinal aganglionosis, Hirschsprung's Disease, megacolon, congenital aganglionic megacolon) see [I.htm#intestinal_aganglionosis intestinal aganglionosis]
(More? Gastrointestinal Tract Abnormalities | Neural Crest Abnormalities)

agglutination

Term used to describe clumping together, as of sperm, often due to infection, inflammation, or antibodies.

Age-specific fertility rates

A statistical value (used by Australian Bureau of Statistics) showing the number of live births (occurred or registered) during the calendar year, according to age of mother, per 1,000 of the female estimated resident population of the same age at 30 June.
(More? Australian Statistics)

agrippi

(Greek, agrippi = "with difficulty" , aegre parti = "delivered with difficulty") Historic birth term used for a breech delivery and born child.
(More? Birth)

Artificial Insemination

(AI) Fertility treatment, using placement of a sperm sample inside the female reproductive tract that can be carried out by a number of different techniques: intracervical insemination, intrauterine insemination, intratubal insemination.
(More? Week 1 Notes)

AIF

Acronym for Apoptosis Inducing Factor.

alar plate

Developmental term for the dorsal region of the developing neural tube (central nervous system), derived from the lateral regions of the nerual plate. In the spinal cord, this is the sensory afferent, dorsal horn region. Nomenclature may have come from the "wing-like" appearance of this region of the folding neural plate.
(More? Neural Notes | Dev Biol Development of the human spinal cord)

alopecia

Term used to describe the loss of hair.
(More? Integumentary Development - Hair)

alpha

Greek letter, (Α capital letter alpha; α lower case alpha) first letter of the Greek alphabet. The lower case form used in scientific literature to designate the first forms/variants of a similar protein, gene, energy form or substance.
(More? [greek.htm Greek Symbols])

alpha-fetoprotein

(AFP) A serum fetal glycoprotein produced by both the yolk sac and fetal liver. The presence of the protein in maternal blood is the basis of a test for genetic or developmental problems in the fetus. Low levels of AFP normally occur in the blood of a pregnant woman, high levels may indicate neural tube defects (spina bifida, anencephaly).
(More? Abnormal Development- AFP test)

alpha-fetoprotein test

(APF test) A prenatal test to measure the amount of a fetal protein in the mother's blood (or amniotic fluid). Abnormal amounts of the protein may indicate genetic or developmental problems in the fetus. Serum alpha-fetoprotein (AFP) is a fetal glycoprotein produced by the yolk sac and fetal liver. Low levels of AFP normally occur in the blood of a pregnant woman, high levels may indicate neural tube defects (spina bifida, anencephaly).
(More? Abnormal Development- AFP test)

alpha methyldopa

(methyldopa) A central alpha agonist used to lower blood pressure. Used as an antihypertensive drug to lower blood pressure in pre-eclampsia, acting by either a direct or indirect central vasodilatory mechanism. A recent study suggests this drug may have a direct effect on placental and/or endothelial cell function in pre-eclampsia patients, altering angiogenic proteins. Drug commercial brandname (USA) "Aldomet", also available in combination with other drugs: methyldopa and chlorothiazide "Aldochlor", methyldopa and hydrochlorothiazide "Aldoril".
(More? Placenta Abnormalities - Pre-eclampsia | Medline Plus - Methyldopa | Effect of antihypertensive therapy with alpha methyldopa on levels of angiogenic factors in pregnancies with hypertensive disorders. Khalil A, Muttukrishna S, Harrington K, Jauniaux E. PLoS ONE. 2008 Jul 23;3(7):e2766. PMID: 18648513)

alpha smooth muscle actin

(SMA) Muscle protein, one of the 6 mammalian actin isoforms. This actin is associated with vascular smooth muscle, but SMA can also be expressed in myofibroblasts, and is involved in cell-generated mechanical tension.

alpha synuclein

A protein found in neurons. A dominantly inherited mutation in alpha-synuclein can cause Parkinson’s disease.
(More? UNSW Cell Biology)

allantois

An extraembryonic membrane, endoderm in origin extension from the early hindgut, then cloaca into the connecting stalk of placental animals, connected to the superior end of developing bladder. In reptiles and birds, acts as a reservoir for wastes and mediates gas exchange. In mammals is associated/incorporated with connecting stalk/placental cord fetal-maternal interface.
(More? Placenta | Week 2 Notes | Gastrointestinal Tract Notes)

allosteric

(Greek allos = other , stereos = solid or three-dimensional) Term used to describe proteins (receptors, enzymes, motors) that have at least 2 sites that alter the protein properties. The active site binds the principal substrate. The regulatory site(s) bind effector molecule(s) that influence the protein's biological activity.

altricial animal

Term used to describe an animal born in a helpless state, with incomplete development of sensory systems at birth. For example rats and mice are born with incomplete development of visual and auditory systems.
(More? Rat Development | Mouse Development | Other Embryos)

Alzheimer's Disease

(AD) A neurodegenerative disease associated mainly with ageing and the most common form of dementia. Involves neurons in the parts of the brain that control thought, memory and language. Histopathology is shown postmortem by extracellular beta-amyloid (Aß) fibrils plus intraneuronal tau (a microtubule associated protein) filaments. Named after Aloysius Alzheimer (1864-1915), a German psychiatrist and neuropathologist first published case of "presenile dementia".
(More? Neural Notes | Medline Plus - Alzheimer's Disease)

amelia

Term used to describe the complete absence of a limb, as described in the original classical classification of limb deficiencies.
(More? Limb Abnormalities - Classification)

amenorrhea

The absence of a menstrual period, it can be either primary (not yet had a period by age 16) or secondary (regular period that has now stopped for 3 months).
(More? Human Menstrual Cycle)

Ames test

(Salmonella test) A mutagenic and carcinogenic test of environmental compounds. Exposure of a modified bacteria to the test compound and their subsequent ability to produce reverse mutations and then resume growth.
(More? Abnormal Development)

amniocentesis

A prenatal diagnostic test involving sampling of amniotic fluid by needle aspiration for genetic analysis.
(More? Prenatal Diagnosis - Amniocentesis)

amnioinfusion

A medical procedure in which a physiologic solution (such as normal saline) is infused into the uterine cavity to replace the amniotic fluid.

amnion

An extraembryonic membrane ectoderm and extraembryonic mesoderm in origin and forms the innermost fetal membrane, produces amniotic fluid. This fluid-filled sac initially lies above the trilaminar embryo disc and with embryoic disc folding this sac is drawn ventrally to enclose (cover) the entire embryo, then fetus. The presence of this membane led to the description of reptiles, bird, and mammals as amniotes.
(More? Placenta Notes | Week 2 Notes)

amniotic fluid

The fluid that fills amniotic cavity totally encloses and cushions the embryo. Amniotic fluid enters both the gastrointestinal and respiratory tract following rupture of the buccopharyngeal membrane. The late fetus swallows amniotic fluid.

amniotic band syndrome

(amniotic bands) A relatively rare abnormality caused by damage to the amnion, producing fiber-like bands that trap periperal structures (arms, legs, fingers, or toes) reducing local blood supply in turn leading to abnormal development of those structures or regions.
(More? Musculoskeletal - Limb Development Abnormalities)


amniotic epithelial cells

(AEC) Cells forming the epithelial layer of the amniotic membrane. These cells have also been used in recent stem cell therapeutic research.
(More? Musculoskeletal - Limb Development Abnormalities)

amniotomy

A parturition (birth) medical procedure thought to speed labor, where the amniotic sac is artificially ruptured using a tool (amniohook).
(More? Normal Development - Birth)

aminopterin

Chemical rodenticide also studied as a chemotherapy drug for treating leukemia and other cancers, it is teratogenic and not used as a rodenticide in the USA because exposure to it is associated with serious birth defect.
(More? Abnormal Development)

amphimixis

(Greek, amphi = on both sides ; mixis = a mingling) Term used to describe fusion of male and female gametes, also used when referring to pronuclei fusion.
(More? Week 1 Notes)

amphiregulin

(AREG) also called schwannoma-derived growth factor (SDGF). A heparin-binding and heparin-inhibited epidermal growth factor (EGF) family member, which stimulates fibroblast and keratinocyte proliferation. In mammary glands, under induction by estrogen, it stimulates mammary epithelium proliferation during puberty.
(More? Integumentary Development - Mammary Glands | Puberty | OMIM - amphiregulin)

ampulla

Term used to describe an anatomical dilation of a tube or canal lumen. Anatomical description of the opening end of the uterine tube lying above the ovary and the enlarged initial segmeny of the semicircular canals of the inner ear vestibular system.
(More? Inner Ear | Genital System - Female Uterus)


amyoplasia

(absent muscle development) Rare developmental abnormality with the newborn showing a lack of muscular development, replaced by other connective tissues, and limb contractures with deformity at most joints. It is also the most common form of arthrogryposis.

Amyotrophic Lateral Sclerosis

(ALS, Lou Gehrig's disease) A postnatal neurological disease of the central nervous system, affecting the spinal cord motor neurons and brain. Henry Louis "Lou" Gehrig (1903-1941), was an American baseball player in the 1920s and 1930s who suffered from this disease.
(More? Neural Notes | Medline Plus - Amyotrophic Lateral Sclerosis)

anagen

The hair follicle active growth phase, hair follicle progenitors derived from the bulge interact with the mesenchymal dermal papilla cells to generate the lineages of the hair follicle (telogen phase is resting phase of hair growth cycle). (More? Integumentary Development - Hair)

anaphase

(Greek, ana = up, again) A mitotic stage, paired chromatids separate and migrate to spindle poles.
(More? Week 1 - Mitosis | Week 1 Notes)

anaphase A

The part of anaphase during which the chromosomes move.
(More? Week 1 - Mitosis | Week 1 Notes)

anaphase B

The part of anaphase during which the poles of the spindle move apart.
(More? Week 1 - Mitosis | Week 1 Notes)

anastomosis

Term used to describe the connection between two tubes. Applied to describe the connection between peripheral blood vessels without an intervening capillary bed.

anacephaly

Neral developmental abnormality, incomplete development of cerebral hemispheres and cranium. Usually related to neural tube defect at the anterior (cranial) neuropore.
(More? Neural Notes | Neural Abnormalities)

androgens

The male sex hormones, eg testosterone.
(More? Genital System - Male)

andrologist

A clinical specialist who treats male reproductive problems associated with spermatazoa.
(More? Week 1 - Spermatogenesis)

aneuploidy

Term used to describe an abnormal number of chromosomes mainly (90%) due to chromosome malsegregation mechanisms in maternal meiosis I.
(More? trisomy 21 | Meiosis)

aneurism

(Greek, aneurysma = a widening, aneurysm) A term used to describe an abnormal widening of a vessel or anatomical tubal structure.
(More? Blood Vessel)

angioblast

The embryonic precursor cell which will form the walls of both arteries and veins.
(More? Blood Vessel)

angiopoietin

(ANGPT) factors of the vascular endothelial growth factor family which are involved with blood vessel development, recognised by two tyrosine kinase receptors (Tie1 and Tie2). Angiopoietin-1 and Angiopoietin-2 appear to have opposite effects acting through the same (Tie2) receptor.
(More? Blood Vessel | OMIM - Angiopoietin 1 | OMIM - Tie2)

Animalia

The kingdom that includes animals, heterotrophic multicellular organisms that undergo embryonic development.

anlage

(German, anlage = primordium) Term used to describe an earlier developmental structure, tissue or cells which will differentiate or develop to form a future structure.

anoikis

(Greek, anoikis = "homelessness") A form of cell death that occurs when cells loose contact with the extracellular matrix (ECM).

anophthalmia

The abnormality of the absence of an eye development within the orbit.

anosmia

Abnormality of having no sense of smell.
(More? Smell | Sensory Notes)

anovulation

The absence of ovulation, failure for an oocyte (egg) to be released from the ovary.
(More? Week 1 Notes)

anterior

Anatomical term used to describe the front or ventral surface.

anterior sacral meningocele

A neural tube defect where herniation of the meninges occurs through a focal opening of a sacrum or coccyx segment. One of the three classes of spinal meningocele (simple, lateral and anterior sacral meningocele).
(More? Neural Abnormalities | Neural Notes)

anterior neuropore

(rostral, cephalic, or cranial neuropore) The initial "head end" or brain end opening of the neural tube before it closes (humans approximately 24 days postfertilization). The opening at the other "tail end" of the neural tube is the posterior neuropore. The anatomical location of the anterior neuropore in later brain development is the lamina terminalis, lying behind the pituitary gland. Failure of anterior neuropore to close leads to the neural tube defect (NTD) anacephaly.
(More? 2009 Lecture - Early Neural Development | Neural Abnormalities | Neural Tube Defects)

anteroventral periventricular nucleus

(AVPV) A hypothalamic nucleus that is larger in females than males and is critical for the female-typical cyclic surge pattern of luteinizing hormone (LH) release. It is an example of sex differences in the developing morphology of the brain.

anticodon

The 3 bases on a transfer RNA (tRNA) complementary to the messenger RNA (mRNA) codon.

anticonvulsants

(antiepileptic drugs) A class of therapeutic drugs that are used to prevent and minimize seizures by acting on either ion channels, active transport, or membrane stabilization. In embryology they are teratogenic and increase the occurance of neural tube defects (NTDs). (Drug examples: Carbamazepine, Clonazepam, Ethosuximide, Phenobarbital, Phenytoin, Primidone, Valproic Acid)
(More? Neural Abnormalities | Neural Tube Defects | Drug Use)

Anti-Mullerian Hormone

(AMH, Mullerian Inhibiting Substance, MIS) A secreted factor (transforming growth factor-beta, TGF-beta superfamily) that regulates gonadal and genital tract development. Inhibits paramesonephric (Mullerian) duct development in males.
(More? Male | OMIM - AMH)

antral follicle

(secondary follicle) Term used to describe the developmental stage of ovarian follicle development following preantral (primary) in describing the sequence (primordial, preantral, antral) of follicle development within the ovary. In humans, a number of primordial follicles will begin to develop into primary follicles, some of which will then form antral follicles (secondary), with only a single antral follicle developing into the ovulating follicle (Graafian) each menstrual cycle.
(More? Week 1 - Oogenesis)

antrum

(Latin from Greek, antron = a cave, cavity; a nearly-closed cavity or bulge). Identified anatomically in many structures (ovarian follicle, bone, cardiac, gastric). In the ovary this refers to the follicular fluid-filled space within the follicle.
(More? Week 1 - Oogenesis)

apgar

Non-invasive clinical test designed by Dr Virginia Apgar (1953) carried out immediately on newborn. The name is also an acronym for: Activity (Muscle Tone), Pulse, Grimace (Reflex Irritability), Appearance (Skin Color), Respiration. A score is given for each sign at one minute and five minutes after the birth.
(More? APGAR | History)

aphalangia

The absence of phalanges (long bones) leading to an absent digit, finger or toe as described in the original classical classification of limb deficiencies.
(More? Limb Abnormalities - Classification | Limb Abnormalities - Hand Classification)

apnea

Respiratory term meaning the cessation of breathing.
(More? Respiratory Notes)

apoptosis

(Greek, apo = away from + ptosis = fall) Programmed cell death which occurs in the development of many systems. e.g. between digits, nervous system. Kerr JF, Wyllie AH, Currie AR. Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer. 1972 Aug;26(4):239-57. Review.
(More? necrosis | apoptosis )

Apoptosis Inducing Factor

(AIF) A mitochondrial protein associated apoptosis by initial chromatin condensation and high molecular weight DNA fragmentation.

appositional growth

(Latin, appositus = to put near) Term used in describing a specific form of bone growth on a pre-existing surface or growth at the periphery (appositus, past participle of appnere, to put near).

aquaeductus vestibuli

(Latin, aquaeductus vestibuli) See vestibular aqueduct, a tubular component of the inner ear.

arachnoid

(Greek, arachne = spider + -oeides = form) A meshwork (spider web-like) connective tissue covering of the central nervous system, forms part of the meningial layers. Lies between tough outer duramater and fine piamater.

Archaea

(Greek, archein = to begin), also called the Archaebacteria The kingdom (or "domain") of single-celled organisms that live under extreme environmental conditions and have distinctive biochemical features.

Archaebacteria

(Greek, archein = to begin), also called the Archaea The kingdom (or "domain") of single-celled organisms that live under extreme environmental conditions and have distinctive biochemical features.

archenteron

(Greek, arche = beginning + enteron = gut) The "primitive gut," the innermost tube of an animal embryo; lined with endoderm, it will become the digestive tract.

arginine vasopressin

(vasopressin, AVP) A hypothalamus neuropeptide hormone stored in the posterior pituitary (neurohypophysis). The hormones actions include: stimulate liver glycogenolysis, contraction of vascular smooth muscle cells and kidney mesangial cells, antidiuresis in the kidney, and aggregation of platelets. Also in mouse, this hormone has been shown to promote maternal behavior.
(More? Endocrine Development - Hypothalamus | Endocrine Development - Pituitary | OMIM arginine vasopressin)

argonaute 2

(Ago2) A protein component of the RNA-induced gene silencing complex, which is crucial for microRNA-mediated repression of target genes. Mouse oocyte studies show a role in early embryonic development.

arrhythmia

(= dysrhythmia) Term refers to cardiac abnormality of heartbeat either fast, slow, or irregular.
(More? Heart Notes)

Arnold-Chiari Malformation

A type of malformation which appears multifactorial (including inherited and acquired). Cerebellar tonsils elongate and herniate through foramen magnum into spinal canal, resulting in compression of parts of the brain and spinal cord, and disruption of cerebrospinal fluid flow. Thought to be fundamentally the same as anencephaly and spina bifida.
(More? Neural Abnormalities)

ART

acronym for Assisted Reproductive Technology. All treatments or procedures that involve the handling of human eggs and sperm for the purpose of helping a woman become pregnant. Types of ART include in vitro fertilization, gamete intrafallopian transfer, zygote intrafallopian transfer, embryo cryopreservation, egg or embryo donation, and surrogate birth.
(More? Week 1 - In Vitro Fertilization)

ART cycle

A process in which 1) an ART procedure is carried out, 2) a woman has undergone ovarian stimulation or monitoring with the intent of having an ART procedure, or 3) in the case of frozen embryos, embryos have been thawed with the intent of transferring them to a woman. A cycle begins when a woman begins taking fertility drugs or having her ovaries monitored.
(More? Week 1 Notes)

arthrogryposis

Term describing the presence of joint contractures at birth, usually associated with the limbs and digits. There are several different forms with amyoplasia being the most common form of this disorder and several types of distal arthrogryposes with contractures of the fingers and toes.

ASD

Acronym for atrial septal defect, a developmental defect in the formation of the dividing septum between the two atria of the heart.
(More? Heart Abnormalities)

asepsis

Term describing a sterile technique, without infection or contaminating microorganisms.

Asherman syndrome

(uterine synechiae, intrauterine adhesions) Maternal syndrome (historic name) resulting from trauma to the gravid uterine cavity, which leads to the formation of intrauterine and/or intracervical adhesions.

ASPM

Acronym for abnormal spindle-like microcephaly-associated protein.

aster

(Latin, aster = star) A star-like object visible in most dividing eukaryotic cells contains the microtubule organizing center.

astral

Having an aster and centrioles that participate in mitosis; characteristic of mitosis in animals and in nonvascular plants.

astral microtubules

Microtubules that extend from each pole of the mitotic spindle without attaching to any other visible structure.

astrocyte

A type of nervous system glial cell (non-neuronal), forms blood-brain barrier.
(More? Neural Notes)

ataxia

(Greek, a = without + taxis = order) Refers to a lack of coordination of muscule movements. Both central and peripherial neurological disorders can generate this loss of coordination.
(More? Neural Notes | Neural Abnormalities | NINDS (USA) Ataxia Telangiectasia)

ataxia telangiectasias

A neurodegenerative disease with no current cure resulting in death in teens or early 20's.
(More? NINDS (USA) Ataxia Telangiectasia | Neural Abnoormalities)

ataxia-telangiectasia mutated

(ATM) A protein kinase involved in early signaling of DNA damage (double-stranded DNA breaks) and initiates the signal transduction cascade at damage sites. ATM phosphorylates substrates involved in DNA repair and/or cell cycle control. See also Rad3-related (ATR) a broad spectrum DNA damage response signaling protein kinase.
(More? DNA Notes OMIM - ataxia-telangiectasia mutated | Entrez - ataxia-telangiectasia mutated)

ataxia-telangiectasia and Rad3-related

(ATR) (= FRAP-related protein 1) A broad spectrum DNA damage response signaling protein kinase.
(More? OMIM - ataxia-telangiectasia and Rad3-related | Entrez - ataxia-telangiectasia and Rad3-related)

atresia

(Greek, a = without + tresis = perforation) Term used for anatomical closing or absence of a cavity or opening that should exist. Used as an antomical, pathological and clinical term: esophageal atresia, biliary atresia, duodenal atresia, jejunal atresia, choanal atresia, vaginal atresia, urethral atresia, pulmonary atresia, bronchial atresia, tricuspid atresia.
(More? see atretic follicle)

atretic follicle

An ovarian follicle that fails to mature and degenerates. Also called "atresia" referring to the process of degeneration of the ovarian follicle. At any one time the majority of follicles are destined not to complete maturation and degeneration can occur at any stage (from type 4-7).
(More? Week 1 Notes | Ovary Notes)

atrial septal defect

(ASD) Heart defect, abnormal opening or hole in the septum between right and left atria. Normally allows left to right blood shunting, though additional cardiac abnormalities causing higher right side pressure (pulmonary stenosis or tricuspid atresia) allow right to left blood shunting.
(More? Heart Abnormalities)

atrioventricular junction

(AVJ) the heart (cardiac) region lying between the two atria and the two ventricles. In the mature heart the opening is closed on the left by the mitral valve (a bicuspid valve, has two distinct leaflets) and on the right by the tricuspid valve (three distinct leaflets).
(More? Heart Notes)

atrophy

Term used to describe the wasting away of tissue.

auditory neurons

Neurons of the auditory ganglia (cochlear ganglia) of cranial nerve 8 (CNVIII) involved with sound detection. These neurons form as part of the anterior ventromedial otocyst epithelium and migrate into the periotic mesenchyme at the anterior part of the developing otocyst. At this location they differentiate and extend dendrites towards the developing sensory epithelia and axons to connect with central brainstem targets.
(More? Inner Ear | Hearing Notes)

auricular hillocks

External ear (auricle) embryonic origin, a series of 6 external "bumps" three on each of pharyngeal arch 1 and 2.
(More? External Ear | Hearing Notes)

Automated Auditory Brainstem Response

(AABR) The basis of a neonatal hearing test that uses a stimulus delivered through earphones and detected by scalp electrodes. Computer ananalysed electrical measurement of activity through nuclei in the hearing central neural pathway.
(More? Child Notes - Neonatal Hearing Screening)

autonomic nervous system

Involuntary nervous system; coordinates the responses of smooth muscles, cardiac muscles, and other effector organs including those of the endocrine, digestive, excretory, respiratory, and cardiovascular systems.
(More? Neural Crest Notes)

autosomal

The term decribing all the chromosomes that contribute to a cell's genetic material, except for the sex chromosomes X, Y.
(More? DNA Notes)

autosomal inheritance

Some hereditary diseases are described as autosomal which means that the disease is due to a DNA error in one of the 22 pairs that are not sex chromosomes. Both boys and girls can then inherit this error. If the error is in a sex chromosome, the inheritance is said to be sex-linked.
(More? DNA Notes)

autotroph

(Greek, autos = self + trophos = feeder) An organism that makes its own organic molecules from simple inorganic compounds (like carbon dioxide water and ammonia).

alveolar

(Latin, alveus = cavity or hollow) Term used in relation to the alveoli of the lungs. The final functional sac of the respiratory tree where gas exchange occurs between the alveolar space and the pulmonary capillaries.
(More? Respiratory Notes)

alveolar stage

(Latin, alveus = cavity or hollow) (aveolar phase) Term used to describe lung development, the final histological/developmental stage (Pseudoglandular, Fetal Canalicular, Terminal sac, Alveolar). This stage occurs from late fetal/neonate. The final functional sac of the respiratory tree exists, where gas exchange occurs between the alveolar space and the pulmonary capillaries.
(More? Respiratory Notes)

alveoli

(Latin, alveus = cavity or hollow) The final functional sac of the respiratory tree where gas exchange occurs between the alveolar space and the pulmonary capillaries.
(More? Respiratory Notes)

auditory tube

(eustacian tube, otopharyngeal tube, pharyngotympanic tube) A narrow canal connecting the middle ear space to the back of the oral cavity. The tube allows ventilation protection and clearance for the middle ear cavity. Ventilation is the pressure equalization in the middle ear. Clearance is to allow fluid drainage from the middle ear. Embryonic origin is from the first pharyngeal pouch. In development, the canal is initially both horizontal, short and very narrow leading to poor drainage and easy blockage.
(More? Middle Ear | Hearing Notes | Abnormal Hearing Notes)

axial mesoderm

Alternative name for the notochord, an early embryonic structure lying in the midline of mesoderm within the early trilaminar embryo.
(More? notochord | Neural Notes | Week 3 Notes)

axon

The neuron specialized cell structure forming the outflow pathway for neural transmission. The input pathway is formed by other specialised cellular processes, dendrites, and connections to the cell body.
(More?2009 Lecture - Late Neural Development)

axon initial segment

(initial segment) Neuron cell body (soma) specialized cellular subdomain at the beginning of the axon, which during neuronal development excludes somatodendritic proteins from the axon and helps maintain neuronal polarity. This cytoplasmic region also contains unique cytoskeletal proteins (βIV spectrin and ankyrin G) involved in clustering voltage-sensitive sodium channels (Nav) at high density to enable action potential spike initiation and propagation.
(More?2009 Lecture - Late Neural Development)


axial process

The precursor to the notochord. In the early embryo (week 3) epiblast structure extending from the primitive node (Hensens node) crainally, which will eventuall differentiate to for the [[N#notochord|notochord], the mesoderm structure that later replaces the axial process.
(More? notochord | Neural Notes | Week 3 Notes)

axoneme

The basic structure in cilia and eukaryotic flagella; consists of parallel microtubules in a characteristic "9 + 2 pattern".
(More? Week 1 Notes)

AZF regions

regions on the long arm of Y chromosome (AZFa, b, and c) deletions of which result in severe damage to spermatogenesis with azoospermia or severe oligozoospermia.
(More? Week 1 - Spermatogenesis | Week 1 Abnormalities)

azoospermia

Term describing the absence of spermatazoa, a male reproductive abnormality.
(More? Week 1 - Spermatogenesis | Week 1 Abnormalities)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G



Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original B

B-Myb

A protein transcription factor and a member of the A-Myb, B-Myb (MybL2) and C-Myb family found in all proliferating cells. B-Myb is the only member of this Myb family specific to embryonic stem cells and is required for both cycle progression and mitotic spindle formation. In mice, lack of the gene leads to early embryonic death, after implantation due to defects on the inner cell mass.

bacteriophage

(Greek, bakterion = little rod + phagein = to eat) or phage A virus that infects bacteria.

Balbiani body

(mitochondrial cloud) collection of cell organelles (mitochondria, ER, and granulofibrillar material) asymmetrically located beside the nucleus in very young oocytes in some species. Appears similar to germinal granule precursors seen some species that contain a definitive germ plasm (flies, worms, and frogs).
(More? PNAS - Mouse oocytes within germ cell cysts and primordial follicles contain a Balbiani body)

Ballottement

(French, ballottement = "a tossing about") Clinical palpatory test (clinical week 6 - 20) used to detect pregnancy, when the lower uterine segment (or cervix) is tapped by examiner's finger, the fetus floats upward, then sinks again and can be felt on the finger. (not considered diagnostic as it can also be elicited in the presence ovarian cysts)

Bardet-Biedl syndrome

(BBS) is an abnormality with triallelic inheritance and is characterized by a rangne of multisystem abnormalities (cone-rod dystrophy, truncal obesity, postaxial polydactyly, cognitive impairment, neural development, male hypogonadotrophic hypogonadism, complex female genitourinary malformations, and renal dysfunction).
(More? Vision Abnormalities | Urogenital Abnormalities | OMIM - Bardet-Biedl syndrome | GeneReviews - Bardet-Biedl syndrome)

Barker Hypothesis

(Fetal Origins Hypothesis) Term named after the researcher, Barker who began a statistical analysis in the UK, of low birth weight data (early 1900's). The hypothesis has since been renamed as the Fetal Origins Hypothesis and proposes that in utero influences can lead too permanent changes in embryo/fetus, low birth weight, which predisposes to chronic disease in adult life.
(More? Fetal Origins Hypothesis Notes)

Barr body

Name given to a visible cellular feature produced by the inactivation of a single X chromosome in females.

Bartholin Gland

(greater vestibular gland) A female genital tract glands which secretes mucus. The equivalent male gland are the Bulbourethral Glands.
(More? Urogenital Notes)

basal body

The base of an axoneme; a cylinder about 500 nm long that resembles a centriole; the microtubule organizing center of a cilium or a eukaryotic flagellum.

basal body temperature

The temperature taken at its lowest point in the day, typically in the morning before getting out of bed. Note body temperature changes are used to approximately establish ovulation (increases bbt).
(More? Human Menstrual Cycle | Hyperthermia)

basal ganglia

(basal nuclei) A central nervous system (CNS) neural structure derived embryologically from the secondary vesicle telencephalon (endbrain) and the earlier primary vesicle prosencephalon (forebrain) from the neural tube. Structurally, it connects the cerebral cortex with the thalamus and brainstem and is associated with motor control and learning.
(More? ANAT2341 Lecture - Ectoderm Development | Notes)

base

Another term for anucleotide (usually a t c g).
(More? DNA Notes)

base pair

Double stranded DNA has nucleotides A-T, C-G, paired by hydrogen bonds (2 for AT, 3 for GC). Note this means that GC is harder to separate that AT.
(More? DNA Notes)


basket cells

Central nervous system cerebellar interneurons located in the cerebellum molecular layer. These GABAergic neurons, and stellate cells, receive an excitatory synaptic input from granule cell axons (parallel fibers) and form an inhibitory synapse with Purkinje cells. The embryonic progenitors arise from the neuroepithelium at the level of of the fourth ventricle.
(More? 2009 Lecture - Early Neural | PMID: 19500566)

basonuclin 2

(bnc2, BNC2) A vertebrate zinc finger transcription factor that has a role in the proliferation of craniofacial mesenchymal cells and therefore in head and face development. (ortholog of drosophila disco proteins)
(More? PMID: 16891417)

Bayley Scales of Infant Development

(BSID) A postnatal (from 1 to 42 months) neurological assessment scale used in screening and diagnosis of development using 178 item mental scale and the 111 item motor scale, the original BSID was revised in 1993 to version 2 (BSID-II). THere are several alternative assessments tests and tasks including: Alberta Infant Motor Scale (AIMS), Fagan Test of Infant Intelligence (FTII), Peabody Developmental Motor Scale II (PDMS-2) Comprehensive Developmental Inventory for Infants and Toddlers (CDIIT), Means-End Problem-Solving Task, Operant Discrimination Learning, Mobile/Train Conjugate Reinforcement Tasks, The Transparent Barrier Detour Task, The A-not-B Task
(More? Neural Notes | Postnatal Development)

bicornuate uterus

("heart-shaped" uterus) Female internal genital tract uterine abnormality, where the paramesonephric ducts (Mullerian ducts) fail to completely fuse forming two separate body parts that fuse close to the opening into the vagina.
(More? 2009 Lecture - Genital Development | Uterine Abnormalities)

biliary cells

The liver epithelial cell formed from hepatoblast differentiation (hepatoblasts form from endoderm).
(More? Gastrointestinal Tract - Liver | GIT Notes)

Billings Ovulation Method

(BOM, Ovulation Method) A self-observation method for women use to monitor their fertility.

biopsy

A fragment of tissue removed for (clinical/pathological/medical) study under the microscope.

biotinidase

An enzyme required to free biotin from its bound form for use. Biotinidase deficiency can be detected in newborn screening and treated with daily biotin supplementation.

biparietal diameter

An ultrasound measurement of Biparietal Diameter (BPD) is used to determine fetal age and normal development (small/large/abnormal) parameters. Measured as the diameter between the 2 sides of the head, used in clinical ultrasound measurements after 13 weeks (2.4 cm) to term (9.5 cm). It is one of the four typical ultrasound assessments of fetal size and age: Biparietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL).
(More? Ultrasound | Head Notes) | Fetal Notes | Birth Notes)

birth

(parturition) Term describing the pysiological process of offspring (child) being born.
(More? Normal Development - Birth)

birth rate

A statictical term typically calculated by dividing the number of live births in a population in a year by the mid-year resident population.
(More? Normal Development - Birth | Statistics | Australian Statistics)

bladder exstrophy

(Greek, ekstriphein = "turn inside out") A congenital malformation with bladder open to ventral wall of abdomen (between umbilicus and pubic symphysis) and may have other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).
(More? Urogenital Abnormalities)

blastema

Term used to describe an undifferentiated mass of cells.
(More? [W.htm#Wilms_tumour Wilm's tumour])

blastocoel

A fluid-filled cavity that exists in early development within the blastocyst. Initially the dividing cells form a solid cellular mass (morula) in which the cavity will form. In humans this cavity is present during the first and second week of development.
(More? Week 1 - Blastocyst)

blastocyst

(Greek, blastos = sprout + cystos = cavity) Term used to describe the hollow cellular mass that forms in early development. The blastocyst consists of cells forming an outer trophoblast layer, an inner cell mass and a fluid-filled cavity. The blastocyst inner cell mass is the source of true embryonic stem cells capable of forming all cell types within the embryo. In humans, this stage occurs in the first and second weeks after the zygote forms a solid cellular mass (morula stage) and before implantation.
(More? Week 1 - Blastocyst | Week 2 Notes | Stem Cell Notes)

blastopore

The opening formed by the gastrulating cell migration in early blastula to gastrula development.
(More? Week 2 Notes | Week 3 Notes | Frog Development - Gastrulation)

blastula

(Greek, blastos = sprout = little sprout) A stage of an animal embryo that consists of a fluid-filled sphere of cells on the surface.
(More? Week 2 Notes)

blighted ovum

(missed abortion, early fetal loss) A historic term now called replaced by ===early fetal loss===, describing embryo loss that occurs in first trimester.

BLIMP1

DNA-binding transcriptional repressor (zinc-finger) which has a role in both embryo development and adult tissues by regulating (repressing) p53 expression allowing normal cell growth.
(More? PNAS Yan J, Jiang J, Lim CA, Wu Q, Ng HH, Chin KC. BLIMP1 regulates cell growth through repression of p53 transcription. Proc Natl Acad Sci U S A. 2007 Jan 30)

blood islands

The initial small patches which form within mesoderm that differentiate into both the blood vessel wall and blood cells. These islands enlarge and connect together to form the initial vascular beds.
(More? Cardiovascular System - Blood)

BMI

Acronym for Body Mass Index which is a measure of body composition. Used to determine adiposity, that is fat content, which has influences upon growth and health.

Bmi1

A proto-oncogene protein located in the nucleus, which is a member of the Polycomb-group gene family (required to maintain the repression of homeotic genes). Expressed in range of stem cells including hematopoietic, neural and intestinal stem cells. Human BMI-1 gene on the short arm of chromosome 10 (10p13). PMID: 18536716
(More? Gastrointestinal Tract Development | OMIM - proto-oncogene BMI-1 |

BOC

Acronym for Brother of Cdon a cell surface receptor. CDON is also a acronym for Cell adhesion molecule-regulated/downregulated by oncogenes. Both Boc and Cdon are cell surface receptors (for sonic hedgehog) of the immunoglobulin (Ig)/fibronectin type III that interact with each other, are coexpressed and involved in neural and muscle development.
(More? Molecular Development - sonic hedgehog | OMIM - BROTHER OF CDON)

bombesin receptor

A cell receptor family associated mainly with gastrointestinal function (motility and secretion) and neural functions (circadian rhythm, thermoregulation anxiety/fear responses, food intake). In mammals, these G protein-coupled receptors are: neuromedin B, gastrin-releasing peptide, and orphan receptor bombesin receptor subtype 3.
(More? GIT Development | Endocrine Development |)

bone

A connective tissue forming the main structural component of the skeleton. There are two processes of bone formation (ossification): endochondrial, replacing a pre-existing cartilage template (most of the skeleton); or intramembranous, ossification directly from a membrane (cranial vault, scapula). Adult bone gross histology is described as either trabecular bone (also called cancellous or spongy bone) or compact bone (does not have any spaces or hollows).
(More? Musculoskeletal Development - Bone | Musculoskeletal Development | Blue Histology - Bone)

bone marrow

The cellular components found within the core of bones, mainly long bones, which contain the adult blood stem cell population and a range of other cell types. Generally described as either red marrow (myeloid tissue) or yellow marrow (mainly fat cells.)
(More? Musculoskeletal Development - Bone | Musculoskeletal Development)

bone marrow stromal cells

(BMSCs) These are pluripotental cells from bone marrow that can potentially differentiate into a range of connective tissue and muscle cell types (cardiomyocytes, rhabdomyocytes, hepatocytes, osteocytes, chondrocytes, tencoytes, adipocytes, smooth muscle cells). These cells have therefore been seen as a source of stem cells for tissue repair.
(More? Musculoskeletal Development - Bone | Musculoskeletal Development)

borrelia burgdorferi

(B. burgdorferi) The agent of Lyme disease in North America and Europe. A species of bacteria of the spirochete class of the genus Borrelia.
(More? Abnormal Development - Bacterial Infection)

Botallo's duct

(ductus arteriosus) A vascular shunt between pulmonary trunk and the aortic arch. This channel degenerates to form the ligamentum arteriosum (ligamentum Botalli). In preterm infants this channel may remain open as Patent Ductus Arteriosus. Named after Leonardo Botallo an Italian surgeon in Paris (1530-1600).
(More? Patent Ductus Arteriosus | PDA Image Heart Notes | Normal Development - Birth)

bowel

(intestine) Term used to describe the midgut and hindgut portion of the gastrointestinal tract running from after the stomach to the anus. Also subdivided into the small bowel (small intestine) and the large bowel (large intestine).
(More? Gastrointestinal Tract Notes)

BPD

Acronym for biparietal diameter, measurement between the 2 sides of the head, used in clinical ultrasound measurements after 13 weeks.
(More? Ultrasound Movies)

brachial plexus

(Latin, bracchium = arm) The mixed spinal nerves innervating the upper limb form a complex meshwork (crossing). :(More? Neural Notes)

brachiocephalic trunk

(Latin, bracchium = arm, cephalicus = head) The blood vessel forming the first branch of the aortic arch, arises superolaterally and splits into the right subclavian and the right common carotid arteries. :(More? Cardiovascular Notes)

brain

The general term for the central nervous system (CNS) component formed initially from the cranial end of the neural tube. The remainder of the CNS is the spinal cord. The brain forms initially as 3 primary brain vesicles which later form 5 secondary brain vesicles.
(More? Neural Notes)

breech

A birth term where the fetal buttocks are presented first, this can also occur in different forms depending on the fetal structure presentation (complete breech, frank breech, footing breech, knee breech).
(More? Normal Development - Birth | Birth Abnormalities)

Brek/Lmtk2

Acronym for brain-enriched kinase/lemur tyrosine kinase 2. Signaling protein member of the Aatyk family of kinases, mouse knockouts are infertile with azoospermia.
(More? Week 1 Notes)

broad ligament

Human female genital tract mesentery formed by a double fold of peritoneum that connects the uterus to the peritoneal floor and walls. Anatomically it has three parts: mesometrium (surrounding the uterus), mesosalpinx (surrounding the uterine tube) and mesovarium (surrounding the ovary).
(More? Genital System - Female)

bronchi

(Latin, bronchos = windpipe) Plural of bronchus, the two subdivisions of the trachea carrying air to the lungs. Embryologically forms as an endodermal outpocket of the foregut which branch (bronchiole, subdivision of the bronchus) as they grow.
(More? Respiratory Notes)

bronchiole

(Latin, bronchos = windpipe) A smaller branch subdivision of the bronchus.
(More? Respiratory Notes)

bronchus

(Latin, bronchos = windpipe) The individual division of the trachea carrying air to the lungs. Embryologically forms as an endodermal outpocket of the foregut which branch as they grow (bronchiole, subdivision of the bronchus).
(More? Respiratory Notes)

brown adipose

(brown fat) Neonatal specialized form of adipose tissue used in mammals to generate body temperature (thermogenic organ) by non-shivering thermogenesis. Adult fat (white adipose) cannot be used in this fashion. This form of adipose tissue is also seen in animals that hibernate.
(More? Musculoskeletal Development - Adipose)

Bruce effect

Reproductive change in female mice, pheromones from a strange male can prevent embryo implantation in recently bred female.
(More? Mouse Development- Estrous Cycle)

buccal

(Latin, bucca = cheek) A term used to relate to the mouth (oral cavity).
(More? GIT Notes)

buccopharyngeal membrane

(oral membrane; Latin, bucca = "cheek") A membrane which forms the external upper membrane limit (cranial end) of the early gastrointestinal tract (GIT). This membrane develops during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm. The membrane lies at the floor of the ventral depression (stomadeum) where the oral cavity will open and will breakdown to form the initial "oral opening" of the gastrointestinal tract. The equivilent membrane at the lower end of the gastrointestinal tract is the cloacal membrane.
(More? buccopharyngeal membrane | GIT Notes | Face Notes | Head Notes)

Bulbourethral Gland

(Cowper's Gland) A male genital tract gland which secretes a small amount of a thick clear mucous fluid prior to ejaculation, the alkaline content apparently buffers acidity of the urethra. The equivalent female gland are Bartholin's glands.
(More? Urogenital Notes)

bulbus cordis

A region of the early developing heart tube forming the common outflow tract, will differentiate to form three regions of the heart.
Blood Pathway: sinus venosus -> atrium -> ventricle -> bulbus cordis (outflow tract)
(More? 2009 Lecture - Heart | Heart Notes)


Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original C

c-section

abbreviation of "caesarian section" also can be further shortened as acronym C/S (see [#caesarian caesarian section]).

caesarian

The surgical delivery of fetus through abdominal incision. Named after the roman emperor Caesar who was delivered by this method. Please note the UK/Australian "Caesarean" versus USA "Cesarean" spelling differences.
(More? Birth Notes - caesarian)

cafe-au-lait spots

(French, cafe-au-lait = coffee with milk) term used to describe the appearance of a type of skin blemishes that can be associated with a neural crest disorder, Neurofibromatosis Type 1.
(More? Neural Crest Abnormalities - Neurofibromatosis)

Cajal bodies

(CB) Ramon y Cajal originally identified these small nuclear organelles in cells, they have various suggested functions and are localized to the nucleolar periphery or within the nucleoli.

Call-Exner bodies

A feature seen in the developing ovarian follicle granulosa layer of some species, including human. Appears as a spherical space staining as an eosinophilic region and contains basal lamina components (type IV collagen and laminin) similar to thiose of the follicular basal lamina.
(More? Week 1 - Oogenesis)

calvaria

The skull formed from frontal, parietal and occipital bones.
(More? Musculoskeletal Notes)

camptodactyly

A term describing abnormal development resulting in a permanent flexion contracture of a finger or toe.
(More? Abnormal Development - FAS)

canalicular stage

(fetal canalicular, canalicular phase) Term used to describe lung development, after early embryonic the second of the histological/developmental stages (Pseudoglandular, Fetal Canalicular, Terminal sac, Alveolar). This stage occurs during the fetal period from week 16 to 24. During this stage there is lung bud mesenchymal angiogenesis and cellular differentiation into different stromal cell types (fibroblasts, myoblasts and chondrocytes).
(More? Respiratory Notes)

cancelled cycle

An ART cycle in which ovarian stimulation was carried out but which was stopped before eggs were retrieved, or in the case of frozen embryo cycles, before embryos were transferred.
(More? Week 1 - In Vitro Fertilization)

Cantrell's pentalogy

A rare human developmental syndrome involving 5 key abnormalities: midline abdominal wall defect, lower sternum defect, anterior diaphragm defect, diaphragmatic pericardium defect and congenital heart malformation.

capacitation

The process by which sperm become capable of fertilizing an egg, requires membrane changes, removal of surface glycoproteins and increased motility.
(More? Week 1 Notes - Capacitation)

cardinal vein

The name given to the initial early vessels that will form the systemic venous system. This vascular system, like most early vessels, develop initially bilaterally and symmetrical.
(More? Blood Vessel Notes | Cardiovascular Notes)

cardiocyte

(cardiomyocyte) The mature cardiac (heart) muscle cell. Cardiac muscle cells are striated, joined by specialised junctions (intercalated discs) and innervated by the autonomic nervous system.
(More? Heart Notes)

Carnegie stages

Carnegie stages are a system of classifying embryonic development based on the external features and related internal changes that affect appearance and growth of the embryo. Note that the stages are not directly dependent on either age or size, but upon the appearance of specific embryonic features. Early human and other species embryos can be classified by these stages. The term "carnegie stages" are named after the famous USA Institute which began collecting and classifying embryos in the early 1900's.
(More? Carnegie Stages | Carnegie Stages - Scanning Electron Micrography | About the Carnegie Institute | Carnegie Stage Comparision)

cartilage

The connective tissue formed from mesoderm by the process of chondrogenesis. In the embryo cartilage initially forms most of the skeleton and is later replaced by bone (ossification). In the adult, cartilage is found in many skeletal regions including the surface of bone joints.
(More? Musculoskeletal Development - Cartilage Development | Musculoskeletal Development)

catabolism

(Greek, cata = down + ballein = to throw) The reactions of metabolism that break down complex molecules, such as those in food.

catagen

The end of active growing phase of the life cycle of the hair, between growing phase (anagen) and resting stage (telogen).
(More? Integumentary Development - Hair)

cauda equina

(Latin, cauda equina = horse's tail) The lower end, caudal, extension of the mature spinal cord. This anatomical feature develops due to the growth, in length, of the vertebral column while the spinal cord does not elongate at the same rate.

caudal

(Latin, caudal = tail) Anatomical term referring to structures that are more towards the tail.

cavitates

Term used to describe the process of formation of a space within an existing solid object. This process occurs developmentally in a number of different structures: in the early blastocyst forming the blastocoel, within early somites forming the somitocoel.

CBU

Acronym for Cord Blood Units, used in defining quantities of placental cord blood collected.
(More? Stem Cells - Cord Blood)

cell division

The process by which a parent cell gives rise to two daughter cells that carry the same genetic information as the parent cell. All body cells divide by the process called mitosis, except germ cells which undergo meiosis. Meiosis is a DNA reductive cell division (diploid to haploid).
(More? Week 1 Notes | Mitosis | Meiosis)

Cell Theory

The historic theory that states: (1) All organisms are composed of one or more cells; (2) cells themselves are alive and are the basic living unit of function and organization of all organisms; (3) all cells come from other cells.
(More? UNSW Cell Biology)

cellular oncogene

A normal gene (proto-oncogene) which when mutated can cause unregulated cellular growth and proliferation, cancer.

central canal

The lumen or cavity of neural tube lying within the spinal cord. This space is continuous with ventricular system of the brain.
(More? Neural Notes)

Central Dogma

The theory that states "DNA specifies RNA, which specifies proteins."

central nervous system

(CNS) The part of the nervous system made up of the brain and spinal cord. Both structures form from the neural tube which is ectoderm in origin.
(More? Neural Notes)

centre of ossification

(ossification centre) The region where bone formation commences within embryonic connective tissue. In endochondrial ossification, this process occurs within cartilage. In membranous ossification, this process occurs within a membrane.
(More? Musculoskeletal Notes)

centriole

A pair of small cylindrical structures each about 0.2 micron in diameter and 0.4 micron long, that lie at right angles to one another; present at each pole of the mitotic spindle in animal cells and in some other eukaryotes.

centripetal

(Latin, centripetal = center seeking) Term used to describe the direction of growth, movement or migration.

centromere

The point at which the two chromatids of a single chromosome are joined.

cephalic

(Greek, kephale = head) Term used to relate to the head or sometimes towards the upper body.
(More? Head Notes | Neural Abnormalities - Cephalic)

cerebellum

(Latin, cerebellum = little brain) A central nervous system component formed from the rhombencephalon (hindbrain) region of the neural tube. The cerebellum is required for coordinated motor activities. Cells within the cerebellum are formed by the ventricular zone of the roof of the fourth ventricle and the second germinal zone (Rhombic lip).
(More? Neural Notes)

cerebral aqueduct

A narrow ventricular cavity within the mesencephalon formed from the cavity within the neural tube.
(More? Neural Notes)

cerumen

The ear wax which is secreted by apocrine glands in the ear canal (external auditory meatus).
(More? Hearing Notes | Head Notes)

cervical flexure

The most caudal brain flexure (of 3) between spinal cord and rhompencephalon.
(More? Neural Notes)

cervical mucus plug

(CMP) During early pregnancy, glands located at the cervical junction between vagina and uterus secrete mucus that forms a plug or barrier between these two structures.

cervical sinus

An ectodermal depression visible externally at the level of the neck during embryonic development (approx carnegie stage 14-16), which marks the region where 2nd pharyngeal arch has grown over 3rd and 4th arches.

cesarean

The surgical delivery of fetus through abdominal incision. Named after the roman emperor Caesar who was delivered by this method. Please note the UK/Australian "Caesarean" versus USA "Cesarean" spelling differences.
(More? Birth Notes - caesarian)

CHARGE Syndrome

Each letter sands for an associated disorder of the syndrome: Coloboma on the eye , Heart, Atresia of choane , Retardation of growth , Genital malformations, Ear malformations and/or deafness. CHARGE syndrome has an estimated birth incidence of 1 in 12,000 and is a common cause of congenital anomalies. Most affected individuals with CHARGE syndrome have mutations involving the chromodomain helicase DNA-binding protein-7

chemotaxis

The movement of a cell toward a higher (or, in some cases, a lower) concentration of a particular chemical.

chiasma

(Greek, chiasma = cross; plural, chiasmata) The sites of exchange of DNA between homologous chromosomes during meiosis; visible during prophase of meiosis I.
(More? Week 1 Notes - Meiosis)

chimera

(Greek, pronounced ky-MIR-uhs) A mythical monster with the head of a lion, the body of a goat, and the tail of a serpent. Today used to describe a mixing of biological molecules either: 1. animals that have been genetically engineered 2. development studies where different species cells have been mixed, example chick-quail chimera, 3. Modified proteins containing parts of 2 different proteins.
(More? Neural Crest Notes)

cholangiocyte

Bile duct epithelial cell derived from hepatoblasts during embryonic liver development. These cells line the bile duct system and have apical cilia. Cholangiocytes function (mechano-, osmo-, and chemo-sensory) to regulate the fluidity and alkalinity of canalicular bile by reabsorptive and secretory events adjusting the final secreted bile composition. Abnormalities associated with these cells development or function are called cholangiociliopathies (polycystin-1, polycystin-2, and fibrocystin).
(More? Gastrointestinal Tract - Liver)

cholecystitis

Inflammation of the gall bladder generally caused by gallstones obstructing the duct from gall bladder to common bile duct and can occur in maternal gall bladder during pregnancy.
(More? GIT Notes- gall bladder | Medline Plus Acute cholecystitis (Gallstones) | The Merck Manual Cholecystitis)

chondrodysplasia

Term used to describe skeletal malformation due to perturbation of chondrocyte differentiation program at the growth plate.
(More? Musculoskeletal Development - Cartilage Development | Musculoskeletal Development)

chondrogenesis

the process of forming cartilage, which is a connective tissue formed from mesoderm (or neural crest in the head region). In the embryo, cartilage initially forms most of the skeleton and is later replaced by bone (ossification). In the adult, cartilage is found in many skeletal regions including the surface of bone joints.
(More? Musculoskeletal Development - Cartilage Development | Musculoskeletal Development)

chordae tendineae

Within the heart ventricles, a series of tendinous chords connecting the ventricular papillary musclular walls with the atrioventricular valves (bicuspid, tricuspid). The ventricular wall attachment is through the trabeculae (trabeculae carneae).
(More? Heart Development)

chorioamnionitis

(CA) An intraamniotic puerperal infection described as having 3 forms: histologic, clinical (clinical chorioamnionitis, IAI), and subclinical. Intraamniotic infection is a common (2-4%) event in labor and the systemic inflammatory response can also lead to preterm birth and neonatal complications.
(More? Placenta Notes)

chorion

An extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.
(More? Placenta Notes)

chorion frondosum

(frondosum = leafy) The chorion found on conceptus oriented towards maternal blood supply where the majority of villi form and proliferate, will contribute the fetal component of the future placenta.
(More? Placenta Notes | Week 2 Notes | Week 3 Notes)

chorion laeve

(laeve = smooth) The smooth chorion found on conceptus away from maternal blood supply (towards uterine epithelium and cavity) with very few villi present.
(More? Placenta Notes | Week 2 Notes | Week 3 Notes)

chorionic somatomammotropin

(CSH, human lactogen) A hormone synthesized within the placenta by syncytiotrophoblast cells. This protein hormone (190 amino acid) has a structure is similar to pituitary growth hormone.
(More? Placenta Notes | OMIM - chorionic somatomammotropin hormone)

chronic lung disease

(CLD) Neonatal chronic lung disease can be caused by prolonged mechanical ventilation (MV) and oxygen-rich gas with premature infants.
(More? Normal Development - Birth | Respiratory Notes)

chronic histiocytic intervillositis

(massive chronic intervillositis, chronic intervillositis) Rare placental abnormality and pathology defined by inflammatory placental lesions, mainly in the intervillous space (IVS), with a maternal infiltrate of mononuclear cells (monocytes, lymphocytes, histiocytes) and intervillous fibrinoid deposition.
(More? Placenta Abnormalities)

chronic intervillositis

(massive chronic intervillositis, chronic histiocytic intervillositis) Rare placental abnormality and pathology defined by inflammatory placental lesions, mainly in the intervillous space (IVS), with a maternal infiltrate of mononuclear cells (monocytes, lymphocytes, histiocytes) and intervillous fibrinoid deposition.
(More? Placenta Abnormalities)

chronic villitis

Placental pathology which can occur following placental infection leading to maternal inflammation of the villous stroma, often with associated intervillositis.
(More? Placenta Abnormalities)

Chorionic villus sampling

(CVS) The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.
(More? Prenatal Diagnosis - Chorionic Villus Sampling)

choroid plexus

A vascular complex in 3rd and 4th ventricle that differentiates to act as an endorgan synthesizing and secreting cerebrospinal fluid (CSF) into the ventricular space of the brain.
(More? Ventricular System | Cerebrospinal Fluid)

chromaffin

The name given to adrenal medulla cells, due to their histological staining with potassium di===chroma===te (brown).
(More? Endocrine Notes | Adrenal Development)

chromatin

(Greek, chroma = color) A diffuse material within the nucleus of a non-dividing eukaryotic cell; consists of DNA and proteins.

chromosomes

(Greek, chroma = color + soma = body, because it is stained by certain dyes) double stranded DNA coiled around histones. Condenses during mitosis and meiosis.

chryptochid testes

A male genital abnormality where the testes remain undescended in the abdominopelvic cavity.
(More? Reproductive System - Abnormalities - Gonadal Descent)

cilia

(Latin, cilium = eyelid) Cellular extensions named from the hair-like appearance of a cilium; singular, cilium. In many tissues, cilia are found as epithelial cell apical surface motile specializations. In the uterine tube epithelium, after ovulation used to move the unfertilized egg, then the fertilized zygote, then blastocyst during the first week of development.

ciliated epithelium

(Latin, cilium = eyelid) An epithelium named on the basis of the cells having surface hair-like appearance of a cilium; singular, cilium. In many tissues, cilia are found as epithelial cell apical surface motile specializations. In the uterine tube epithelium, after ovulation used to move the unfertilized egg, then the fertilized zygote, then blastocyst during the first week of development.

cilium

(Latin, cilium = eyelid) Cellular extension named from the hair-like appearance of a cilium; plural, cilia. In many tissues, cilia are found as epithelial cell apical surface motile specializations. In the uterine tube epithelium, after ovulation used to move the unfertilized egg, then the fertilized zygote, then blastocyst during the first week of development.

circular DNAs

Genetic material structure found in bacteria, energy-producing organelles (mitochondria, chloroplasts), and many viruses.

cis-regulatory element

(Latin, cis = on the same side) Gene expression regulation, named because the regulatory element is on the same piece of DNA that is being regulated.

Clara cells

Respiratory tract epithelial cells on the luminal surface of airways. These cells have a dome shaped cytoplasmic protrusion and no cilia and their function is secretory and xenobiotic. Clara cells can act as progenitor cell in small airways replacing injured terminally differentiated epithelial cells.
(More? Respiratory Notes)

claudin

A protein family which forms a component of tight junctions located between cells in the subapical region of the lateral membranes. These proteins in epithelial cells can interact with Eph/ephrin proteins during development to affect cell migration and allow cell sorting to occur.

claudius cells

(cells of Claudius) Cells of the inner ear cochlea, columnar cells with microvilli overlying the basilar membrane and extend from Hensen's cells to the spiral prominence. Barrier cells that lie external to the organ of corti in endolymph.
(More? Lecture - Hearing)

clavicle

(Latin, clavis = key, -cula = small, "collar bone") The bone which locks shoulder to body. In mammals, the clavicle is one of the first bones to ossify by a mix of intramembranous and endochondral ossification from two centres of ossification within a single condensation. The suggested bird equilivant, the furculae (wishbone), ossifies only by intramembranous within a single center in each condensation.
(More? Musculoskeletal Development- Bone | Casselman's- Clavis)

cleavage

A series of rapid cell divisions following fertilization in many early embryos; cleavage divides the embryo without increasing its mass.

cleavage furrow

A structure, groove, formed from the cell membrane in a dividing cell as the contractile ring tightens.
(More? Week 1 Notes)

cleft

An anatomical gap or space occuring in abnormal development in or between structures. Most commonly associated with cleft lip and cleft palate. Term is also used to describe the groove that forms between each pharyngeal arch during their formation.
(More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)

cleft lip

An abnormality of face development leading to an opening in the upper lip. Clefting of the lip and or palate occurs with 300+ different abnormalities. Depending on many factors, this cleft may extend further into the oral cavity leading to a cleft palate. In most cases clefting of the lip and palate can be repaired by surgery.
(More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)

cleft palate

An abnormality of face development leading to an opening in the [P.htm#palate palate], the roof of the oral cavity between the mouth and the nose. Clefting of the lip and or palate occurs with 300+ different abnormalities. In most cases clefting of the lip and palate can be repaired by surgery.
(More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)

cleidocranial dysplasia

A human genetic bone disease due to a heterozygous mutation in Runx2.
(More? Bone Development)

clinodactyly

(Greek, klinein = to bend, slope or incline and dactylos = digit, finger or toe) a curving of the fifth (little) finger toward the fourth (ring) finger. Can be associated with a number of genetic syndromes (trisomy 21 Down syndrome and Klinefelter (XXY) syndrome) or other skeletal abnormalities.
(More? Limb Abnormalities)

clinical trials

Clinical experimentation on patients and are designated as phase I, II, or III, based on the type of question and number of people in the study.
  • Phase I clinical trials researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
  • Phase II clinical trials the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.
  • Phase III clinical trials the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely. (text modified from NIH Clinical Trials site)

clinodactyly

A musculoskeletal abnormality of development resulting in permanent curving of the fifth finger, usually toward other fingers and can also be seen for other fingers or toes.
(More? Abnormal Development - FAS)

cloacal membrane

Forms the external lower membrane limit (caudal end) of the early gastrointestinal tract (GIT). This membrane is formed during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm. The membrane breaks down to form the initial "anal opening" of the gastrointestinal tract.
(More? [B.htm#buccopharyngeal_membrane buccopharyngeal membrane] | GIT Notes)

clockface

A term used to describe the appearance of plasma cell nuclei due to the clumping of the chromatin at the nucleus periphery. More clearly seen in tissue plasma cells that the bone marrow smear, where they are sometimes confused with the basophilic erythroblasts.
(More? [heart20.htm Blood Notes] | GIT Notes)

clomiphene citrate

(CC) A fertility drug taken orally to promote the process of follicle/egg maturation in superovulation therapy. (CC) an anti-estrogen (MRL-41) therapy for WHO group II (eu-oestrogenic) infertility associated with polycystic ovary syndrome. Used for more than 40 years it is a simple, cheap treatment, with low side effects and yields a 25% live birth rate. Alternative therapeutics being considered are metformin, aromatase inhibitors and low-dose FSH.
(More? Greenblatt RB, Barfield WE, Jungck EC, Ray AW. Induction of ovulation with MRL/41. Preliminary report. JAMA. 1961 Oct 14;178:101-4. | Homburg R. Clomiphene citrate--end of an era? A mini-review. Hum Reprod. 2005 Aug;20(8):2043-51.) | Notes - Ovary | Week 1 - In Vivo Fertilization | Week 1 - In Vitro Fertilization | Week 1 - Abnormalities)

clone

(Greek, klon = twig) A population of genetically identical individuals or cells descended from a single ancestor.

club foot

The historic common (slang) term for [T.htm#talipes_equinovarus talipes equinovarus] a congenital deformity of the foot (occurs approximately 1 in 1,000 births).
(More? [T.htm#talipes_equinovarus talipes equinovarus])

CNS

Acronym for Central Nervous System. The structures formed from the neural tube, the brain and spinal cord.
(More? Neural Notes)

coacervate

(Latin, coacervatus = heaped up) Discrete tiny droplet into which proteins and polysaccharides can spontaneously concentrate.

coagulation plug

The uterine epithelium feature located where the blastocyst had entered the uterine wall. In humans, seen approximately day 12 following fertilization.
(More? Week 2 Notes)

coarctation

(Latin coartare = to press together) Term used to describe a narrowing (stricture, constriction) associated with aortic arch developmental abnormality.
(More? Cardiovascular Abnormalities)

coarctation of the aorta

(Latin coartare = to press together) Term used to describe a developmental abnormality of narrowing (stricture, constriction) of the aortic arch.
(More? Cardiovascular Abnormalities | Coarctation of Aorta)

coated pit

A depression in the plasma membrane, lined with clathrin molecules; an intermediate structure in receptor-mediated endocytosis.


cochlear sac

Embryonic hearing structure, which will form the coiled cochlear duct and contribute to the saccule.
(More? Lecture - Hearing)

cochlear aqueduct

A bony channel containing the fibrous periotic duct. It connects the basal turn of the cochlea perilymphatic space with the subarachnoid space of the posterior cranial cavity.
(More? Lecture - Hearing)

cochlin

A protein forming the major constituent of the inner ear extracellular matrix.

(More? Lecture - Hearing)

codominant

Refers to two alleles that each contribute to the phenotype of a heterozygote.

codon

A group of three nucleotides that specifies a single amino acid residue.

coelom

Term used to describe a space. There are extraembryonic and intraembryonic coeloms that form during vertebrate development. The single intraembryonic coelom will form the 3 major body cavities: pleural, pericardial and peritoneal.
(More? Coelom Notes)

coelocentesis

A sampling of extracoelomic fluid usually for an early prenatal diagnostic technique.
(More? Coelom Notes | Prenatal Diagnosis)

coenzyme

An organic molecule (but not a protein) that is a necessary participant in an enzyme reaction.

collagen

A helical fibrous abundant protein of the extracellular matrix. The regular structure found principally in the structural protein collagen; the collagen helix consists of three polypeptide chains.

colostrum

The maternal mammary gland secretion that occurs at birth which precedes the secretion of milk.
(More? Normal Development - Milk | Integumentary Development - Mammary Glands)

column chromatography

A type of chromatography in which the stationary phase is an insoluble material packed into a glass or metal column.

commensalism

An association between individuals of two species in which one organism benefits without harming the other one.

communicating junctions

Membrane-associated structures that allow small molecules to pass freely between two adjacent cells.

comparative genomic hybridization

(CGH, comparative genomic hybridisation, chromosomal microarray analysis) A prenatal screening technique that allows detection of chromosomal abnormalities. This new technique is currently also being developed and tested for in vitro fertilization screening.
(More? Prenatal Diagnosis - Comparative Genomic Hybridization | PMID: 19411132)

competitive inhibitor

A molecule whose inhibitory effects on an enzyme can be overcome by increased substrate concentration.

complement

A set of blood proteins that attack microbial invaders.

complementarity determining region

(CDR) The segment of an immunoglobulin molecule most involved in binding antigen; so called because its shape is complementary to that of the antigen.

complex disease

Types of diseases which aggregate in families but do not segregate in a Mendelian fashion.

conceptus

The entire product of conception, that is all the structures derived from the zygote and includes not only the embryo, but also the placental and membrane components.
(More? Week 1 Notes)

conductive loss

The term used to describe one of the two major classes of hearing loss involving external and middle ear abnormalities (other form is sensorineural loss).

congenital

Already present at birth, often used to describe defects present at birth, congenital defects.
(More? Abnormal Development)

congenital adrenal hyperplasia

(CAH, adrenal virilism) Abnormality of the fetal adrenal cortex, alters cortisol and androgens with different effects dependent upon sex: in females masculization of the external genitalia; in males, disorder often unnoticed until postnatally. In both sexes, accelerated skeletal growth and sexual maturation is seen in late childhood. Caused by a deficiency or absence of the enzyme 21-hydroxylase in the adrenal cortex. Grouped with the Disorders of Sex Development (DSD).
(More? Endocrine Adrenal - congenital adrenal hyperplasia | Reproductive System - Abnormalities)

Coombs test

A diagnostic test named after Robin Coombs (1921-), a British immunologist who developed a technique of using antibodies that are targeted against other antibodies used in the test for erythroblastosis fetalis (Haemolytic disease of the newborn).
(More? Placenta Development- Abnormalities | Blood Groups and Red Cell Antigens Hemolytic disease of the newborn)

cord blood

(human umbilical cord blood, HUCB) A term used to describe blood collected from the placenta usually after birth. Has been identified as a source of stem cells with potential therapeutic uses and is stored in Cord Blood Banks throughout the world.
(More? Placenta Development | Stem Cell)

cord presentation

A term used to describe at birth the presence of the umbilical cord between the fetal presenting part and the cervix, with or without membrane rupture.
(More? Birth Notes | Placenta Development- Abnormalities)

cord prolapse

A term used to describe at birth the descent of the umbilical cord through the cervix alongside (occult) or past (overt) the presenting part in the presence of ruptured membranes (incidence of 0.1% to 0.6%).
(More? Birth Notes | Placenta Development- Abnormalities)

corneal stroma

An eye structural component of the cornea. In chicken, formed by a two-stage process of collagen fibril deposition, a primary stroma secreted by epithelial cells and a secondary stroma by the invading neural crest cells (corneal keratocytes).
(More? Eye Notes)

corona radiata

The granulosa cells that directly surround the oocyte, within the antral follicle of the ovary. These cells are released along with the oocyte at ovulation and provide physical protection and the initial structural barrier that spermatazoa must penetrate during fertilization. Other granulosa cells within the follicle include: [M.htm#membrana_granulosa membrana granulosa] and [#cumulus_oophorus cumulus oophorus].
(More? Week 1 - Oogenesis)

corpus albicans

(Latin, corpus = body, albicans = whitish) The histological structure formed by the degenerating corpus luteum in the ovary if implantation does not occur and the hormone hCG is not released. The structure is white, not yellow, because of the absence of steroid hormone synthesis/accumulation.
(More? Week 2 Ovary | Week 1 Notes)

corpus luteum

(Latin, corpus = body, luteum = yellow) The remains of ovarian follicle after ovulation that acts as an endocrine organ (produce progesterone and oestrogens) supporting pregnancy and preventing menstruation (loss of the endometrial lining). Formed by proliferation of both follicular granulosa cells (granulosa lutein cells) and thecal cells (theca lutein cells) after ovulation, which produce progesterone and oestrogens. de Graaf first observed it in the ovary of a cow as a yellow structure, caused by accumulation of steroidal hormones.
(More? Week 2 Ovary | Week 1 - Oogenesis)

cortex

(Latin, corticalis = at the outside) outer layer, used in association with medulla (innner layer or core) a general description that can be applied to describing an organ with a layered structure. Also used to describe the outer cellular (grey matter) layer of the central nervous system.

cortical

(Latin, corticalis = at the outside) like the bark of a tree, usually combined with medulla meaning the core. Also used to describe the outer cellular layer of the central nervous system.

cortical plate

The outer neural tube region which post-mitotic neuroblasts migrate too along radial glia to form adult cortical layers.
(More? Neural Notes)

corticosteroid

A steroidal hormone produced by the adrenal cortex.
(More? Endocrine Notes)

corticotropin-releasing hormone

(CRH) A hypothalamic neuropeptide hormone, which is also produced by embryonic trophoblast and maternal decidua cells, with receptors in several reproductive organs. Thought to have a role in endometrial decidualization, blastocyst implantation and early maternal tolerance.

cotyledon

(Greek, kotyle = a deep cup) In the embryos of seed plants, the "seed leaves," in which nutrients are stored for use after germination. Used also to describe the structure of the placenta.
(More? Placenta Notes)

Cowper's Gland

(Bulbourethral Gland) A male genital tract gland which secretes a small amount of a thick clear mucous fluid prior to ejaculation, the alkaline content apparently buffers acidity of the urethra. The equivalent female gland are Bartholin's glands.
(More? Urogenital Notes)

cranial flexure

(midbrain flexure) The most cranial brain flexure, between the mesencephalon and prosencephalon, of the three flexures (bends) that develop as the nueral tube grows and elongates.
(More? Neural Notes)

craniofrontonasal syndrome

(CFNS) A human X-linked developmental disorder caused by a mutation in ephrin-B1 affecting mainly females. Characterised by abnormal development of cranial and nasal bones, craniosynostosis (premature coronal suture fusion), and other extracranial anomalies (limb polydactyly and syndactyly).
(More? Musculoskeletal Development - Skull Development)

craniopharyngioma

A common destructive tumorogenic lesions of the hypothalamus and pituitary gland. Can occur when remnant cells from Rathke's pouch remain forming a tumour.
(More? Endocrine - Hypothalamus | Endocrine - Pituitary )

craniorachischisis

Abnormal development of the neural tube defect class with an abnormal opening of the skull and vertebral column.


craniorachischisis totalis

Abnormal development of the neural tube defect class, with failure of fusion of the entire neural tube.

craniosynostosis

The term describing the premature closure of the skull sutures, or fusion of skull bones. May cause skull and brain abnormalities. There are at least 8 different disorders with six related to the fibroblast growth factor receptor (FGFR); Pfeiffer syndrome, Apert syndrome, Crouzon syndrome, Beare-Stevenson syndrome, FGFR2-related isolated coronal synostosis, Jackson-Weiss syndrome, Crouzon syndrome with acanthosis nigricans (AN), and Muenke syndrome.
(More? Head Notes | Head Abnormalities | Bone Notes | Bookshelf - GeneReviews)

CREB

Acronym for Cyclic-AMP response element binding protein. CREB is a member of the basic region leucine zipper (bZIP) family of transcription factors and requires phosphorylation to become a biologically active transcriptional activator. CREB binds to CRE (Cyclic-AMP response element) which is the final target of many extracellular and intracellular signals (e.g. cAMP, calcium, neurotrophins).
(More? Molecular Development)

CrebA

Acronym for Cyclic-AMP response element binding protein A involved in gene activation. Drosophila have two genes (A and B-17A) encoding the cAMP response element binding (CREB) protein family members. These proteins have mammalian equilivants with RNA polymerase II transcription factor activity, DNA binding, transcription factor activity, protein homodimerization activity.
(More? Molecular Development)

cretinism

The term describing a neurological abnormality due to insufficient thyroid hormone during neural development. The main cause of this disorder is an insufficiency or lack of iodine in the diet.
(More? Endocrine Development - Thyroid | Abnormal Development - Iodine Deficiency)

cribiform plate

Anatomical structure of the head, describing the perforated portion of ethmoid bone of skull allows passage of olefactory axons from nasal epithelium to olefactory bulb.
(More? Senses Notes)

CRISP

Acronym for cysteine-rich secretory protein, a group of proteins (CRISP1, CRISP2) recently suggested to have a role in sperm-egg fusion through binding to egg-complementary sites.
(More? Fertilization)

cristae ampullaris

Inner ear structure associated with equilibrium located in the ampulla of the membranous semicircular canals a region with both supporting and hair cells. The hair cell cilia are embedded in the gelatinous cupula.
(More? Lecture - Hearing)

critical period

(critical period of development) The term used to describe a developmental time when exposure to a teratogen can lead to a developmental abnormality, which can be further divided into an early major and later minor developmental abnormality. The defined critical period will differ in timing and length for different systems.
(More? Abnormal Development - Environmental)

CRL

Acronym for Crown-Rump Length. Used in embryology to accurately stage the early embryo. Used in clinical ultrasound as a measurement between the periods of 7 to 13 weeks as an accurate estimation of the gestational age.
(More? Embryo Stages | Ultrasound Movies)

Crown-rump length

(CRL) A measurement used in embryology to more accurately stage the early embryo. Measured from the curvature at the top (crown) to the curvature at the bottom (rump) of the "C-shaped" early embryo. Used in clinical ultrasound as a measurement between the periods of 7 to 13 weeks as an accurate estimation of the gestational age.
(More? Embryo Stages | Ultrasound Movies)

cryptopatches

(CPs) An immune system structure, small clusters of lymphoid cells with an immature lymphocyte phenotype and dendritic cells found associated with the gastrointestinal tract.

cryopreservation

A technique for freezing tissue or cells to preserve for use at a later date. In this report, cryopreserved embryos are referred to as frozen embryos.

cryptophthalmos

The term describing an anomaly of eye development, with a continuity of the skin from the forehead to the cheek over a malformed eye. Classified into three types: complete, incomplete and abortive.
(More? Eye Abnormalities)

cryptorchidism

An abnormality of either unilateral or bilateral testicular descent, occurring in < 30% premature and 3-4% term males. Descent may complete postnatally in the first year, failure to descend can result in sterility.
(More? Urogenital Notes | Genital Abnormalities)

CSH

Acronym for chorionic somatomammotropin hormone, a placental hormone.

cuboidal epithelium

An epithelial layer formed by cells with a cuboidal shape (morphology), compared to the other two main hsitological cell shapes (squamous, columnar). Cuboidal, equal height and width, for example, endodermal or peripheral ectodermal layers of the trilaminar embryo.

cumulus oophorus

(Latin cumulus = a little mound G. oon = egg + phorus = bearing) The granulosa cells that form a column of cells that attaches the oocyte to the antral follicle wall within follicles of the ovary. This column of cells is broken or separates during ovulation to release the oocyte from its follicle attachment. Other granulosa cells within the follicle include: membrana granulosa and corona radiata.
(More? Week 1 - Oogenesis)

cupular deposits

In the vestibular system, the basophilic material on the cupulae of the semicircular ducts, an postnatal ageing phenomenon seen in some vestibular labyrinth.

cyst

The pathological term describing a fibrous capsule containing fluid.

cyto-

(Greek, kytos = hollow vessel or container) Prefix referring to a "cell" or "cellular", as is the the suffix "-cyte".

cytochrome

(Greek, kytos = hollow vessel + chroma = color) One of a set of heme-containing electron carrier proteins that change color as they accept or donate electrons.

cytokinesis

(Greek, kytos = hollow vessel + kinesis = movement) The division of the cytoplasm and formation of two separate plasma membranes.
(More? Week 1 Notes)

cytomegalovirus

An infection of early embryos is fatal, infection of later fetuses can lead to blindness, deafness, cerebral palsy, and mental retardation.
(More? Abnormal Development- Virus)

cytotrophoblast

The "cellular" trophoblast layer surrounding (forming a "shell") the early implanting conceptus. Beginning at uterine adplantation, proliferation and fusion of these cells is thought to form a second outer trophoblast layer, the [S.htm#syncytiotrophoblast syncytiotrophoblast]. The cytotrophoblast layer contributes to formation of the placental villi, the functional component of the fetal placenta.
(More? Week 2 Notes | Placenta Notes | human Chorionic Gonadotrophin)

cytosine

(cytosine triphosphate) One of the four types of nucleotides (ATCG) that make up DNA. Base pairs with guanine by 3 hydrogen bonds.

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original D

Dact1

(Dapper, Antagonist of Beta-Catenin 1) An intracellular protein that binds the membrane protein Vangl2, expressed at the primitive streak epithelial–mesenchymal transition region. Mutations of this gene in mouse (Frodo mouse or Dapper Xenopus) mimic human malformations in the spine, genitourinary system and distal digestive tract.
(More? OMIM Dapper)

dactyly

(Greek, daktulos = finger or digit) used as a siffix with words describing limb abnormalities associated with either fingers on the hand or toes on the foot. For example, polydactyly is an abnormality resulting in additional fingers or toes.
(More? Limb Abnormalities)

damaged DNA-binding protein

(DDB) two proteins (DDB1 and DDB2) that form a complex which recognizes ultraviolet-damaged (UV) DNA and begins repair process (nucleotide excision repair, NER). This complex has been shown to be required for (mouse) epidemis and hair follicle development.
(More? Skin Notes | OMIM - DDB1 DDB2 | PMID: 17301228)

Dandy-Walker malformation

(DWM) The most common cerebellum development malformation in humans. Recently found to be associated with FOXC1, which leads to cerebellar vermis hypoplasia (CVH) and also affects eye development and glaucoma.
(More? Neural Abnormalities | Neural Notes)

DAX1

Acronym for "D"osage sensitive sex reversal (DSS), "A"drenal hypoplasia congenita (AHC) critical region on the "X" chromosome, gene "1" , (gene NR0B1) is a nuclear hormone receptor involved in female ovary development.
(More? Urogenital Notes | OMIM Entry DAX1)

DAZL

Acronym for DAZ-like due to homology to DAZ (Deleted in AZoospermia), a gene on the long arm of the Y chromosome that is frequently deleted in infertile men with nonobstructive azoospermia.
(More? Spermatogenesis | OMIM Entry DAZL)

Deaf-1

Acronym for "D"eformed "e"pidermal "a"utoregulatory "f"actor-"1", a transcription factor that regulates epithelial cell proliferation and side-branching in mammary gland development. A small Rho-like GTPase (Rac3) has been identified as a potential target of Deaf-1 in mouse mammary epithelial cells. Also expressed in central nervous system, dorsal root ganglia, submandibular gland, epidermis and embryo mammary placodes.
(More? Integumentary Development - Mammary Glands | OMIM Entry Deaf-1 | PMID: 18826651)

DDB

Acronym for damaged DNA-binding protein complex. This complex, consisting of two proteins DDB1 and DDB2, recognizes ultraviolet-damaged (UV) DNA and begins repair process (nucleotide excision repair, NER). Required for (mouse) epidemis and hair follicle development.
(More? damaged DNA-binding protein | Skin Notes)

decidua

(Latin, decidua = a falling off) The term given to the uterine endometrium following implantation and signaling which transforms the uterine stromal cells (fibroblast-like).
(More? Placental Notes | Week 2 Notes | Endocrine Notes | Genital Notes)

decidua basalis

The term given to the uterine endometrium at the site of implantation where signaling transforms the uterine stromal cells (fibroblast-like) into decidual cells. This forms the maternal component of the placenta, the decidualization process gradually spreads through the remainder of the uterus, forming the decidua parietalis.
(More? Placental Notes | Week 2 Notes | Endocrine Notes | Genital Notes)

decidua capsularis

The term given to the uterine endometrium which has been converted to decidua surrounding the conceptus on the smooth chorion side.
(More? Placental Notes | Week 2 Notes | Endocrine Notes | Genital Notes)

decidua parietalis

The term given to the remainder of the uterine endometrium, away from the site of implantation, that gradually becomes comverted to decidua.
(More? Placental Notes | Week 2 Notes | Endocrine Notes | Genital Notes)

decidual cell

The uterine stromal cells (fibroblast-like) that differentiate in response to both steroid hormones (progesterone) and embryonic signals. These cells then alter uterine environment to support further embryonic development as well as producing cytokines related to prolactin (PRL) and have an innate immune function.
(More? Placental Notes | Week 2 Notes | Endocrine Notes | Genital Notes)

decidualization

The process by which uterine stromal cells differentiate in response to both steroid hormones and embryonic signals into large epitheliod decidual cells. This process is essential for the progress of implantation and establishing fetal-maternal communication.
(More? Placental Notes | Week 2 Notes | Endocrine Notes)

delta cell

Cells located within pancreas endocrine islets that secretes somatostatin.
(More? Endocrine Development - Pancreas | Endocrine Notes | Gastrointestinal Notes)

Delta-like ligand

(Dll) one of two (Delta and Serrate family) plasma membrane (transmembrane) ligands for the Notch family of receptors. Vasular endothelial growth factor (VEGF) induces one form (Dll4) to acting in negative feedback regulatoion to prevent excessive blood vessel formation
(More? Cardiovasular - Blood Vessel | Molecular Development- Vascular Endothelial Growth Factor | OMIM - Dll4)

Delta-like ligand (Dll) 4

Delta-like ligand (Dll) 4, a transmembrane ligand for the Notch family of receptors, ... Dll4 is induced by VEGF as a negative feedback regulator and acts to prevent overexuberant angiogenic sprouting

dendrite

A thin cellular process found in neurons that bring signals towards the neuron's cell body (soma).
(More? Neural Notes)

dentin

The bone-like material in body of tooth, lacks osteocytes.

dentin phosphophoryn

(DPP) is part of dentin sialophosphoprotein (DSPP) synthesized in both mesenchyme and epithelium, involved in two developmental processes: epithelial-mesenchymal interactions and branching morphogenesis.

dermatome

Early embryonic portion of the somite that will contribute the dermis and hypodermis of the skin.
Development: mesoderm - paraxial mesoderm - somite - dermomyotome - dermatome - dermis
(More? Week 3 - Somitogenesis | Musculoskeletal Development | Integumentary Development)

dermomyotome

Early embryonic portion of the somite that will divide to form both the dermatome and myotome. The dermatome will contribute the dermis and hypodermis of the skin. The myotome will contribute the skeletal muscle of muscoloskeletal system.
Development sequence: mesoderm to paraxial mesoderm to somite to "dermomyotome" then dermatome and myotome
(More? Week 3 - Somitogenesis | Musculoskeletal Development | Integumentary Development)

DES

Diethyl stilbestrol or diethylstilbetrol, a drug prescribed to women from 1938-1971 to prevent miscarriage in high-risk pregnancies. Acts as a potent estrogen (mimics natural hormone) and therefore a potential endocrine disruptor. Female fetus, increased risk abnormal reproductive tract and cancer. Male fetus, abnormal genitalia. Banned by USA FDA in 1979 as a teratogen, previously used as livestock growth promoter.
(More? Abnormal Development)

Descemet's Membrane

Develops from corneal stroma and ectoderm, a specialized basement membrane of the endothelial cells which lies between the corneal stroma and the endothelial layer of the cornea. Named after the French physician Jean Descemet (1732-1810).
(More? Eye Notes)

DET

Acronym for Double-Embryo Transfers, two embryos transferred when women undergo Assisted Reproduction Technology compared to single-embryo transfer (SET).
(More? Week 1 - In Vitro Fertilization)

DNA

Acronym for "D"eoxyribo"N"ucleic "A"cid. The genetic material found in mammalian chromosomes and mitochondria. Consisting of 4 nucleic acids (ATCG) that combine in a triptych (3 nucleotide) code for protein amino acids (3 nucleotides = 1 amino acid).
(More? DNA Notes)

DNA duplex

double stranded base-paired DNA forming a helix.
(More? DNA Notes)

dermatoglyphic

The line patterns (ridges) on the skin found on the palms of the hands (finger and palm prints) and soles of the feet.
(More? Skin Notes)

dermatome

The sensory region innervated by a single spinal (nerve) segment.
(More? Neural Notes | Skin Notes)

dermomyotome

The dorsolateral half of each somite that forms the dermis and muscle. Paraxial mesoderm forms the somite which segregates into scleretome and dermomyotome, which will further divide into dermis (connective tissue) and myotome (developing muscle).

diabetes insipidus

The disorder is related to the hormone antidiuretic hormone (ADH, also called vasopressin) its synthesis, secretion, receptors and signaling pathway. In diabetes insipidus there is an excretion of large amounts (up to 30 litres/day) of a watery urine and an unremitting thirst.
(More? Kidney Abnormalities - Diabetes Insipidus)

diabetes mellitus

A disease due to inadequate regulation of blood glucose usually by altered production of insulin by the pancreas. There are three main types of diabetes: Type 1 (Insulin-Dependent Diabetes Mellitus), Type 2 and gestational diabetes.
(More? Endocrine- Pancreas | Maternal Diabetes)

Diabetes Type 1

(Insulin-Dependent Diabetes Mellitus (IDDM), juvenile onset diabetes) The disease is due to the pancreas not making insulin. It can occur at any age, though it usually arises in childhood or youth, hence juvenile onset diabetes. An autoimmune disease progressive destruction of the insulin-producing beta cells in the pancreatic islets. Has both a genetic and environmental component to the disease development.
(More? Endocrine- Pancreas | Maternal Diabetes | Medline - Diabetes Type 1)

Diabetes Type 2

The most common (80%) form of diabetes. The disease due to noninsulin-dependent diabetes, where body becomes resistant to insulin a life-long disease marked by high levels of sugar in the blood.
(More? Endocrine- Pancreas | Maternal Diabetes | Medline - Diabetes Type 2)

diamniotic

A twinning term, where the twins have two amniotic sacs, which can occur in both early and late monozygotic twinning. In a monozygotic twinning event (one fertilised egg and a single spermatazoa, form a single zygote) which occurs early (within 2 days of fertilization) where each embryo then develops separately its own chorionic sac (placenta) and amnionic sacs (dichorionic diamniotic). Later splitting (more than 2 days after fertilization) may result in a shared placenta and only duplication of the embryonic amnionic sacs (monochorionic diamniotic twins).
(More? Monozygotic Twinning | Twinning | Week 1 Twinning)

dysraphism

The term often used to describe the defective fusion of the neural folds. The position and degree of failure of fusion will result in either embryonic death or a range of different neural defects. The way (mode) in which the human neural tube fuses has been a source of contention. In humans, fusion appears to initiate at multiple sites but the mode is different from that found in many animal species used in developmental studies. The severity dependent upon level within the tube and degree of failure (caudal failure - spina bifida, cranial failure - anancephaly)
(More? ANAT2341 Lecture - Ectoderm Development | Neural Abnormalities)

diastema

A toothless region found in mice between the incisor and the first molar. Thought to result from murine evolutionary loss of incisor, canine, and premolars.
(More? Mouse Notes)

Dicer

A small (21 nucleotide) regulatory RNA required in RNA interference and small temporal RNA (stRNA) pathways to produce the active small RNA component that represses gene expression.
(More? Cartilage Notes | Molecular Development | OMIM - DICER | Pubmed Review)

dichorionic

A twinning term, in a monozygotic twinning event (one fertilised egg and a single spermatazoa, form a single zygote) which occurs early (within 2 days of fertilization) where each embryo then develops separately its own chorionic sac (placenta) and amnionic sacs (dichorionic diamniotic). Later splitting (more than 2 days after fertilization) may result in a shared placenta and only duplication of the embryonic amnionic sacs (monochorionic diamniotic twins).
(More? Monozygotic Twinning | Twinning | Week 1 Twinning)

diencephalon

(encephalon = brain) the embryonic neural tube region that will form the thalmus, hypothalmus and other nuclei in the adult brain. The diencephalon is the second most anterior of the 5 secondary brain vesicles formed from division of the prosencephalon (forebrain) primary brain vesicle (there are 3 primary brain vesicles). It is at the level of the diencephalon that the optic stalks (optic nerve) extends from the brain. The diencephalon lumen (cavity of the neural tube) will form the third ventricles.
(More? Neural Notes | Ventricular System)

diaphragm

A general term for a membranous sheet. The muscular sheet separating chest from abdomen with several different embryonic origins. Regular contraction of the diaphragm is required in respiration.
Embryonic origins: the transverse septum (septum transversum) provides the tendon of the diaphragm, 3rd to 5th somite pairs provide the musculature of diaphragm, ventral pleural sac provides connective tissue, mesentry of oesophagus provides the connective tissue around oesophasus and IVC, and pleuroperitoneal membranes provide the connective tissue around central tendon.
(More? Respiratory Development - Diaphragm | Respiratory Notes | Musculoskeletal Notes)

diaphysis

An anatomical bone term describing the shaft of long bones.
(More? Musculoskeletal Notes - Bone)

differentiation

The process of development of specific cell types from stem cells by gene activation and repression.

diffusion

(Latin, diffundere = "to pour out") Random movements that lead to a uniform distribution of molecules both within a solution and on the two sides of a membrane.

dihydrotestosterone

The hormonally active form of testosterone (male sex hormone) produced by enzyme (5-alpha reductase) conversion. In the male embryo, this can occur in the genital skin which then supports external genital development. In the adult, this conversion occurs in a number of different tissues. A known treatment for prostate cancer include 5-alpha reductase inhibitors.
(More? Urogenital Notes | Endocrine Notes )

dioscorea bulbifera

A plant, the "air potato" which contains the steroid diosgenin used historically for progesterone synthesis.
(More? Human Menstrual Cycle - Birth Control)

diploid

(Greek, di = double + ploion = vessel) Having two sets of chromosomes.
(More? Week 1 Notes)

Disorder of Sex Development

(DSD) A new terminology to describe disorders of sex development. The previous human sex development terminology (intersex, true hermaphrodites, male pseudohermaphrodites and female pseudohermaphrodites) are considered outdated and stigmatising and have been replaced with the general term "Disorders of Sex Development" (DSD) established by the Consensus statement on management of intersex disorders. International Consensus Conference on Intersex. Lee PA, Houk CP, Ahmed SF, Hughes IA; International Consensus Conference on Intersex organized by the Lawson Wilkins Pediatric Endocrine Society and the European Society for Paediatric Endocrinology. Pediatrics. 2006 Aug;118(2):e488-500. PMID: 16882788 | Pediatrics Link
(More? Reproductive System - Abnormalities)

diverticulum

(Latin, diverticulum = by-road) blind tubular process, also used to describe a sac or pouch in organ or seen in the colon. Occurs often in development when a new structure is forming from a epithelia or tract branch or in the initial/early stages of an epitheilal-mesenchymal interaction. The plural term is diverticula. Can also be found in normal and abnormal adult anatomical structures.
(More? Developmental Mechanism - Epithelial Mesenchymal Interaction | GIT Abnormalities - Meckel's Diverticulum)

dizygotic twins

Twins resulting from two fertilization events, that is involving two seperate ova and sperm.
(More? Abnormalities - Twinning | Week 1 - Twinning)

Dolly

The name given to the first cloned sheep (1996) generated from an adult mammary gland cell. The name "Dolly" came from Dolly Parton a play on the mammary cell association.
(More? Week 1 - Cloning)

dominant gene

A gene determining phenotype, allelic pair is therefore resessive.
(More? DNA Notes)

dominant inheritance

With autosomal dominant inheritance, there is an error in one of the 22 chromosome pairs. But the damaged gene dominates over the normal gene received from the other parent. If one of the parents has a disease caused by an autosomal dominant gene, all the children will have a 50 per cent risk of inheriting the dominant gene and a 50 per cent chance of not inheriting it. The children who do not inherit the damaged dominant gene will not themselves suffer from the disease, nor will they be able to pass the gene on to future children. This type of inheritance is present for example in Huntington's disease.
(More? DNA Notes)

donor embryo

An embryo formed from the egg of a woman who has donated it for transfer to a woman who is unable to conceive with her own eggs (the recipient). The donor relinquishes all parental rights to any resulting offspring. (More? Week 1 Notes)

doppler velocimetry

A prenatal diagnostic technique using ultrasound which can measure the flow rate of liquids through various vessels including: utero-placental vessels, fetal brain, heart, liver perfusion, and ultrasound evaluation of fetal organs. (Prenatal Diagnosis)

dormant

(French, dormire = to sleep) Referring to a stage in the development of a seed, in which growth is suspended until restarted by environmental cues.

dorsal aorta

Major embryonic blood vessel lying in the splanchnic mesoderm running the length of the embryo, begins as a pair of dorsal aortas which fuse to form a single vessel. Will eventually form the descending thoracic aorta.
(More? Heart Notes)

dorsal root ganglia

(drg, spinal ganglia) The sensory ganglia derived from the neural crest lying laterally paired and dorsally to the spinal cord (in the embryo found ventral to the spinal cord). Connects centrally with the dorsal horn of the spinal cord.
(More? Neural Crest Notes)

Down syndrome

Common name for trisomy 21, the most common human aneuploidy where an extra copy of chromosome 21 is found in the cell genome.
(More? trisomy 21)

down syndrome cell adhesion molecule

(DSCAM) Protein member of the immunoglobulin superfamily and a new class of neural cell adhesion molecules. Expressed in the developing nervous system for neuronal cell recognition in the process of self-avoidance. Potentially responsible for the Down syndrome mental retardation and visceral anomalies (Hirschsprung disease, intestinal atresia).
(More? trisomy 21)

dpc

Acrynomn for days post coitum, used often in staging embryonic development in animal models.

DSD

Acronym for Disorders of Sex Development.
(More? Reproductive System - Abnormalities)

DTPa

Acronym for "D"iptheria-"T"etanus-acellular "P"ertussis vaccine.
(More? Normal Development- Immunization)

ductus venosus

The vitelline blood vessel lying within the liver that connects (shunts) the portal and umbilical veins to the inferior vena cava and also acts to protect the fetus from placental overcirculation. Absence can cause hydrops fetalis and the umbilical vein then drains directly into the inferior vena cava or right atrium. Postnatally this shunt functionally closes then structurally closes and degenerates to form it the ligamentum venosum.
(More? Cardiovascular Notes)

duodenum

(Latin, duodenarius = twelve, due to approximate length of 12 finger-widths) First part of small intestine lying between the end of the stomach (pyloric valve) and the jejunum.
(More? Gastrointestinal Tract Notes)

ductal plate

A mesenchymal structure in the developing liver that is remodelled to generate the intrahepatic bile ducts (IHBD). Developmental abnormalities, "ductal plate malformation", arise from failure to reorganise.
(More? Gastrointestinal Tract Notes - Liver Development)

ductuli efferentes

In the testis (male gonad) series of tubular structures which arise from the rete testis and conduct spermatazoa into the ductus epididymidis. Their columnar epithelium lining consisting of both absorptive and ciliated cells (giving rise to "cogwheel appearance) which removes much of the fluid associated with the spermatazoa leaving the testes (also by the upper epididymis) thereby increasing the spermatazoa concentration.
Spermatozoa Duct Pathway: seminiferous tubule - straight tubule - rete testis - ductuli efferentes - ductus epididymidis - ductus deferens - urethra
(More? Spermatogenesis | Genital - Male | Genital Notes)

ductus arteriosus

(Botallo's duct) A prenatal vascular "shunt" which connects the left pulmonary artery and the descending aorta. Postnatal neonatal patency (patent ductus arteriosus, PDA) is a relatively common congenital cardiac anomaly occurring more frequently in premature infants.
(More? Cardiovascular System Development | Cardiovascular Abnormalities)

ductus epididymidis

(epididymidis) male testes tubular structure which arise from the ductuli efferentes and conduct spermatazoa into the ductus deferens (vas deferens). The long duct is lined by a tall pseudostratified columnar epithelium.
Spermatozoa Duct Pathway: seminiferous tubule - straight tubule - rete testis - ductuli efferentes - ductus epididymidis - ductus deferens - urethra
(More? Genital - Male | Genital Notes)

dura mater

(Latin, dura mater = hard mother) A tough outer connective tissue meningial coat of central nervous system. (overlays arachnoid and piamater layers) Duramater at the level of the spinal cord is separated from the periosteum of the vertebral canal by an epidural space.
(More? Neural Notes | Axial Skeleton Notes)

dynorphin

Protein whos full biological function unknown, 2 possibilities. In development, neuroendocrine regulation of the developing hypothalamo-pituitary-adrenal (HPA) axis. Secondly, a potential endogenous opioid peptide which has a high affinity for the kappa-opioid receptor.
(More? Endocrine Notes)

dysmenorrhoea

A period pain which can be primary (increased sensitivity to the prostaglandins) or secondary (pathological), can be common with no associated abnormality or in association with ovarian cysts or endometriosis.
(More? Human Menstrual Cycle)

dysraphism

(Greek, rhaphe = suture) clinical term used to describe defective fusion of neural folds. The position and degree of failure of fusion will result in either embryonic death or a range of different neural defects. The way (mode) in which the human neural tube fuses has been a source of contention. In humans, fusion appears to initiate at multiple sites but the mode is different from that found in many animal species used in developmental studies.
(More? Neural Abnormalities | Neural Notes | Neural Tube Defects)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original E

EAE

Acronym for Experimental Autoimmune Encephalomyelitis, an animal model of autoimmune demyelination diseases such as in immune encephalomyelitis and multiple sclerosis (MS)
(More? experimental autoimmune encephalomyelitis).

early fetal loss

Previously called blighted ovum or missed abortion, the term in fact generally describes embryo loss in first trimester.

eclampsia

A serious clinical condition occuring during pregnancy leading to seizures or coma, which can occur in women with preeclampsia (high blood pressure and protein in the urine).
(More? Placenta)

ECMO

Acronym for ExtraCorporeal Membrane Oxygenation an invasive therapy that has been investigated and utilized in newborn infants with cardiorespiratory failure.

ectoderm

(Greek, ecto = outside + derma = skin) One of the initial 3 germ cell layers, which will form the nervous system from the neural tube and neural crest and also generates the entire epithelial layer of the skin covering the embryo. The ectoderm is formed from the epiblast following gastrulation, with a central columnar epithelium (neural plate) and lateral cuboidal epithelium and is continuous with and forms the epithelium that lines the amniotic cavity. In humans, the ectoderm forms during week 3 and 4 of development.
(More? Week 3 - Trilaminar Embryo | Week 3 Notes | Neural Notes | Integumentary Development)

ectopic pregnancy

(Greek, ektopos = out of place) A pregnancy in which the fertilized egg implants outside of the uterus usually in the fallopian tube, but also on the ovary, or the abdominal cavity. Ectopic pregnancy is a dangerous condition that must receive prompt treatment.
(More? Week 2 - Abnormalities)

ectoplasmic specialization

(ES) A specialized cell junction located between Sertoli cells with blood-testis barrier (basal ES) and Sertoli cells with developing spermatids (apical ES). This histological feature of sperm development is described as a "hybrid" of several tyical junction types (adherens junctions, tight junctions and focal contacts).
(More? Week 1 - Spermatogenesis)

ectomesenchyme

The term used to describe ectoderm derived neural crest which contributes in the head region skeletogenic mesenchyme (cartilage, bone, dentine, and connective tissue) which in the body region are typically derived from mesoderm. The head region non-ectomesenchymal derivatives are neurons, glia and pigment cells.
(More? Neural Crest Notes)

effacement

A birth (parturition) term, referring to the shortening or thinning of the cervix, in preparation for birth.
(More? Normal Development - Birth)

egg

(oocyte or ovum) An alternative term used to describe the haploid female reproductive cell Germ Cell). The term is also used to describe the avian and reptilian shell enclosed structure.
(More? Week 1 Notes | Chicken Development | Frog Development)

egg coat

(vitelline layer, zona pellucida) The specialized extracellular matrix surrounding the egg and has different names in different species. In non-mammalians, (sea urchins, chickens) it is the vitelline layer. in mammals, this layer is called the zona pellucida.
(More? Week 1 - Oogenesis | Chicken Development)

egg retrieval

(also called oocyte retrieval) A clinical in vitro fertilization (IVF) procedure to collect the eggs contained in the ovarian follicles.
(More? Week 1 - In Vitro Fertilization)

egg transfer

(also called oocyte transfer) A clinical in vitro fertilization (IVF) technique to transfer of retrieved eggs into a woman's fallopian tubes through [L.htm#laparoscopy laparoscopy]. This procedure is used only in gamete intrafallopian transfer (GIFT) (see definition).
(More? Week 1 - In Vitro Fertilization)

embryo

(Greek, en = in + bryein = to be full of) An egg that has been fertilized by a sperm and undergone one or more divisions. Also the set of early developmental stages in which a plant or animal differs from its mature form.
(More? Embryonic Development)

embryonic period

(embryonic stage, organogenic period) In humans, the first 8 weeks of development is considered the embryonic stage and is divided into 23 Carnegie stages based upon developmental milestones. This has also been described as the "organogenic period". The following time (week 9 to 36) is considered the fetal period.
(More? Embryonic Development | Embryo Stages | Fetal)

embryology

(Greek, en = in + bryein = to be full of) The science of studying embryo development, usually applied to all development before birth (in humans, included both the embryonic and fetal period).
(More? UNSW Embryology | embryo stages)

embryo transfer

Placement of an embryo or embryos into a woman's uterus through the cervix after in vitro fertilization (IVF) or in the case of zygote intrafallopian transfer (ZIFT) (see definition), into her fallopian tube.
(More? Week 1 Notes)

eminence

An anatomical description for a narrow extension from a larger structure. Synonyms: tuberosity, a protuberance.
(More? hypopharyngeal eminence | median eminence | Head Notes)

encephalopathy

Term used to describe any diffuse disease of the brain that alters brain structure or function due to a wide range of teratogens.
(More? Neural Notes)

endocardium

The epithelial membrane lining the inside surface of heart.
(More? Heart Notes)

endochondral ossification

(Greek, endon = within) The term used to describe the process of replacement of cartilage, which forms the first embryonic body skeleton, with bone. The osteoblasts are the bone-forming cells.
(More? Musculoskeletal Development - Bone)

endocrine

(Greek, endon = within) Glands which release hormones into the blood stream. There are many specialized organs and tissues that release hormones into the bloodstream.
(More? Endocrine Notes)

endocrine disruptors

Term used to describe environmental chemicals that interfere with hormone function. Three main forms of interference: Mimic (effects of natural hormone), Block (binding of hormone to receptor or synthesis), Interfere (with hormone transport or elimination).
(More? Endocrine Abnormalities)

endocrine gland

(Greek, endon = within) A gland (organ, tissue) that is specialized for secretion of a hormone into the bloodstream for general circulation.
(More? Endocrine Notes)

endocytosis

(Greek, endon = within) The process of taking in materials from outside a cell in vesicles that arise by the inward folding ("invagination") of the plasma membrane.

endoderm

(Greek, endo = inside + derma = skin) One of the initial 3 germ cell layers, formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract. Note that in the GIT it contributes both epithelium and the associated epithelial glands. In humans, endoderm forms during week 3 of development.
(More? Week 3 - Gastrulation | Week 3 Notes)


endoglin

A cell surface transmembrane receptor for members of the transforming growth factor-beta (TGF-β) superfamily. Expressed on cardiovascular progenitors and then restricted to endothelial cells. In mouse, during formation of the cardiac endocardial cushions, expression is required for the endocardial to mesenchymal transition.
(More? PMID: 19703439)

endolymphatic sac

(Greek, endo = inside) An inner ear structure of the membranous labyringth that has anatomically both an intraosseous and extraosseous component. The sac is connected to membranous labyringth by the endolymphatic duct and has functions regulating endolymph that are both secretory and absorptive. Also the site of endolymphatic sac tumours (papillary cystadenoma of the vestibular aqueduct) either occurring sporadically or associated with the autosomal-dominant von Hippel-Lindau (VHL) disease, due to a germ line mutation.
(More? Hearing - Inner Ear)

endometrial gland

The mucous secreting gland associated with the epithelium lining the uterus. These glands develop and secrete each menstral cycle and are thought to provide initial blastocyst nutrition prior to implantation.
(More? Week 1 Notes)

endometriosis

Endometrium found incorrectly located possibly in the muscular layer of the uterus. Can also be seen as the presence of tissue similar to the uterine lining in locations outside of the uterus, such as the ovaries, fallopian tubes, and abdominal cavity.
(More? Week 1 Notes)

endometrium

The epithelium lining of the non-pregnant uterus. During pregnancy this epithelium undergoes changes described as the decidual reaction and is renamed the "decidua".
(More? Week 1 Notes | Human Menstrual Cycle)

endoplasmic reticulum

(ER) (Greek, endon = within + plasmein = to mold + Latin, reticulum = network) An extensive and convoluted network of membranes within a eukaryotic cell continuous with the outer nuclear membrane and divided into two distinct functional regions (smooth = SER and rough = RER).

Endosulfan

The commercial name for a chemical (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro- 6,9-methano-2,4,3-benzodioxathiepin-3-oxide) broad-spectrum insecticide and [A.htm#acaricide acaricide] to control agricultural insect and mite pests in crops. Technical-grade endosulfan is composed of two stereochemical isomers, alpha-endosulfan (70%) and beta-endosulfan (30%). An Indian study has suggested that it acts as an [#endocrinedisruptors endocrine disruptor], exposure in male children may delay sexual maturity and interfere with sex hormone synthesis.
(More? Endocrine Notes | PubMed Environ Health Perspect. 2003 Dec;111(16):1958-62)

endosymbiosis

(Greek, endon = within + syn = together + bios = life) The close association of two organisms, one of which lives inside the other. The mitochondria within all our cells today are thought to have been derived from just such an arrangement.

endothelium

A simple squamous epithelium lining blood vessels.
(More? Cardiovascular System - Blood Vessels)

ENS

Acronym for the gastrointestinal tract enteric nervous system.

enteral

Nutritient delivery as fluid into the gastrointestinal tract. Can be used to describe postnatal nutrition through milk as well as a clinical method for delivering nutrition to patients.
(More? Postnatal Gastrointestinal Tract | Milk)

enteric nervous system

(ENS) Gastrointestinal tract neural network located within the tract wall that locally controls and coordinates intestinal functions (motility, epithelial secretion and blood flow) derived mainly from the neural crest.
(More? Neural Crest Notes)

enteroendocrine cells

Endocrine cells found within the epithelium of the gastrointestinal tract that secrete enterohormones.
(More? Endocrine Notes | Gastrointestinal Tract Notes)

entheses

The insertion sites where tendons and ligaments meet bone (osteotendinous junctions, osteoligamentous junctions).

entodermal

Historic term for "endodermal" germ cell layer and the embryonic structures which it forms.

ENU

Acronym for N-ethyl-N-nitrosourea. ENU is a mutagen which can induce point mutations in DNA. Mutagenesis is by transferring an ethyl group to oxygen or nitrogen radicals in DNA, resulting in mispairing and base-pair substitution if not repaired.

ependyma

(Greek ependyma = upper cloak or garment) cell (ciliated squamous to columnar) epithelial membrane lining the cerebral ventricles (brain) and central canal (spinal cord).

ephrin-B1

(Eph) A receptor protein-tyrosine kinase, mutations in this gene in human generates craniofrontonasal syndrome (CFNS): ocular hypertelorism, face malformation, cranium bifidum occultum, and craniosynostosis.
(More? OMIM - ephrin-B1)

epicotyl

(Greek, epi = above) The axis of a developing plant above the attachment point of the cotyledons.

epiblast

(Greek, epi = above, upon) the layer (of the bilaminar embryo) that generates endoderm and mesoderm by migration of cells through the primitive streak. The remaing cells form ectoderm.

epidural space

The space existing between the duramater of the spinal cord and the periosteum of the vertebral canal appears during the last week of the embryonic period (stages 20-23) around the circumference of the spinal cord. Patelska-Banaszewska M, Wozniak W. The development of the epidural space in human embryos. Folia Morphol (Warsz). 2004 Aug;63(3):273-9. PMID: 15478101
(More? Neural Notes | Cerebrospinal Fluid | Axial Skeleton Notes)

epigenetics

(Greek, epi = above, upon) gene silencing that occur without changes in the genes (DNA) sequence, this changes can also be inherited.
(More? Molecular Mechanisms - Epigenetics | DNA Introduction | Science - Epigenetics: A web tour | The Welcome Trust - Epigenetics)

epigenome

(Greek, epi = above, upon) entire genome including silencing that occur without changes in the genes (DNA) sequence, this changes can also be inherited.
(More? Molecular Mechanisms - Epigenetics)

epiglottis

(Greek, epi = above, upon) cartilaginous part of the larynx above the glottis, which in infancy directs food into the esophagus and not the trachea. Embryologically it develops in the foregut from the hypobranchial eminence, behind the undeveloped tongue, from which it separates at about 7 weeks. Postnatal anatomical development in humans involves a maturational descent in infancy (4 and 6 months of age). Contains lymphoid tissue (larynx-associated lymphoid tissue, LALT and Bronchus-associated lymphoid tissue, BALT).
(More? Respiratory Notes | Gastrointestinal Tract Notes)

epiphenomenon

(Greek, epi = upon, phenomena = observable occurrence) Term used to describe a secondary symptom or effect unrelated to the original disease or disorder. A side-effect is a specific kind of epiphenomenon that does occur as a direct consequence of the original disease or disorder.

epiphyseal plate

(Greek, epi = upon) The region within growing bones initially occupied by cartilage (hyaline) region (between the epiphysis and diaphysis) allows lengthwise growth of a bone. In the puberty, rapid growth in this region leads to height increase, which then ossifies in the adult.
(More? Musculoskeletal Notes)

epithelial tissue

(Greek, epi = upon + thele = nipple) Cells tightly linked together to form a sheet with little extracellular matrix.

epithelium

(Greek, epi = upon + thele = nipple) Cells tightly linked together to form a sheet with little extracellular matrix. Most epithelia (plural) in the body are embryonically derived from ectoderm or endoderm germ layers. Note: not "skin" which is the epithelium and includes the underlying connective tissue layers (mesoderm) and melanocytes (neural crest) forming a complex tissue.

epoophoron

(rete ovarii, broad ligament cyst) A group of epithelial tubules that can be located in the mesosalpinx possibly mesonephric in origin. Occurs when a segment of the mesonephric duct remains in the female, associated with either the ovary and broad ligament. This "male remnant" will appear as a cyst (broad ligament cyst, adnexal papillary cystadenoma of probable mesonephric origin, APMO) with an appearance that differs depending upon the state of differentiation when the original abnormality occurred.
(More? Urogenital Notes | Genital Notes)

epiglottis

(Greek, glotta = "tongue") Anatomical structure which covers the trachea during swallowing, preventing substances from entering the trachea and then lung. The epiglottis develops from hypobrachial eminence

eppin

A serine protease inhibitor within the epididymis that coats the surface of human spermatozoa. The eynzme has an unknown function, though it has been shown to modulate prostate specific antigen (PSA) hydrolysis of semenogelin (a major protein of seminal fluid).
(More? Spermatozoa Capacitation)

ergodicity

A statistical physics theory that states: anything that can happen will happen.

erythropoietin

a protein hormone (from kidneys) that stimulates bone marrow stem cells to produce red blood cells. Can now be artifically manufactured in the laboratory to treat anaemia (following kidney failure).

ES cell

An Embryonic Stem cell derived from the inner cell mass of the blastocyst, which is totipotential and can be grown undifferentiated in tissue culture (in vitro).
(More? Stem Cell Notes)

Escherichia coli

(E. coli) A common eubacterial resident of the human gut.
(More? Gastrointestinal Tract Notes | Postnatal Gastrointestinal Tract Notes)

estrogens

Sex hormone found in both male and female. In the female, this hormone is produced by the ovaries and is responsible for development of secondary feminine sex characteristics. Together with progesterone these hormones also regulate changes that occur each menstral cycle. In the male, Leydig cells produce estrogen into the rete testis fluid at variable levels in different species. During male embryonic development exposure to high levels of estrogen can lead to genital abnormalities.
(More? Human Menstrual Cycle)

estrous cycle

The cyclic alterations in animal female tract and in sexual receptivity related to hormone changes. When searching both American (estrous) and British (oestrous) spellings are used in the literature.
(More? Menstrual Cycle - Estrous Cycle | Mouse estrous cycle)

etiolated

(French, etioler= to blanch or whiten) Having a thin, spindly appearance, poor leaf development, and no chlorophyll production.

Eubacteria

(Greek, eu = true) The commonly occurring prokaryotes that live in water or soil, or within larger organisms; Archaebacteria and Eubacteria differ from each other in their metabolic abilities, the composition of their membranes, and the structure of their ribosomes.

eukaryotic

(Greek, eu = true + karyon = nucleus) Referring to cells that contain a nucleus and other membrane bounded organelles. Note American spelling eucaryotic.

eukaryotic flagellum

(Latin, flagellum = whip) Plural is flagella. A protein assembly, consisting of microtubules, that can move a cell through a liquid medium (or a liquid medium over a cellular surface); a single cell usually contains only one or two flagella; eukaryotic flagella have the same organizational plan as cilia but flagella are much longer.

eustacian tube

(auditory tube, otopharyngeal tube, pharyngotympanic tube) A narrow canal connecting the middle ear space to the back of the oral cavity. The tube allows ventilation protection and clearance for the middle ear cavity. Ventilation is the pressure equalization in the middle ear. Clearance is to allow fluid drainage from the middle ear. Embryonic origin is from the first pharyngeal pouch. In development, the canal is initially both horizontal, short and very narrow leading to poor drainage and easy blockage.
(More? Middle Ear | Hearing Notes | Abnormal Hearing Notes)

exon

A block of protein encoding sequence of DNA in a gene. Many proteins are made of several exons "stitched" or spliced together by editing out non-coding (intron) sequences.
(More? DNA Notes)

exosome

The macromolecular complexe that post-transcriptionally regulate gene expression by degrading messenger RNAs.
(More? Molecular Notes | UNSW Cell Biology)

expectant management

A clinical term associated avoiding treatment and letting the miscarriage take its natural course, often associated wit first trimester miscarriage (early fetal loss).

experimental autoimmune encephalomyelitis

(EAE) an animal model of autoimmune demyelination, such as in multiple sclerosis (MS).
(More? PMID: 16632554)

exstrophy

(Greek, ekstriphein = "turn inside out", bladder exstrophy, cloacal exstrophy) Term used to describe developmental abnormalities where the structure has been anatomically inverted. For example, bladder exstrophy, a congenital malformation with bladder open to ventral wall of abdomen (between umbilicus and pubic symphysis) and may have other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).
(More? bladder exstrophy | Urogenital Abnormalities)

exstrophy of the bladder

See bladder exstrophy

external auditory meatus

The canal from external ear (auricle) to the tympanic membrane (eardrum). Formed by the first pharyngeal cleft.
(More? Head Notes)

extracellular matrix

(ECM) The material secreted by cells and which they are embedded. Connective tissues contain large amounts of extracellular matrix and epithelial cells sit on a specialized extracellular matrix, the basal lamina. The oocyte is surrounded by a specialized extracellular matrix, the [Z.htm#zona_pellucida zona pellucida]. Extracellular matrix can be different in different tissues and consists of fibers (mainly collagen) and ground substance.
(More? Cell Biology 2009 Lecture - Extracellular Matrix | UNSW Cell Biology 2008 Lecture - Extracellular Matrix)

extrahepatic bile ducts

(EHBDs) Gastrointestinal term used to describe the liver and gall bladder hepatic, cystic, and common bile ducts.
(More? GIT Notes - Liver | GIT Notes - Gall Bladder)

extraembryonic membrane

Term used to describe each of the amnion, yolk sac, allantois and chorion membranes. Amniotic membrane, ectoderm origin innermost membrane, produces amniotic fluid (reptiles, bird, and mammals are amniotes). Yolk sac, endoderm origin, associated with nutrition in reptiles and birds (mammals source of primordial germ cells and blood cells). Allantois, endoderm origin, in reptiles and birds acts as a reservoir for wastes and mediates gas exchange; in mammals is associated/incorporated with connecting stalk/placental cord fetal-maternal interface. Chorioic membrane, mesoderm origin, outermost layer in reptiles and birds acts in gas exchange; in mammals incorporated into the placenta and its functions.
(More? Placenta | Week 2 Notes | Gastrointestinal Tract Notes)

extraembryonic coelom

The space found outside the embryo, amniotic and chorionic space.

extraembryonic mesoderm

Cells from the conceptus that contribute to placenta and fetal membranes. Described as "extraembryonic" because it is tissue lying outside the embryonic trilaminar disc (ectoderm, mesoderm and endoderm) and "mesoderm", because of the connective tissue cellular organization.
(More? Placenta | Week 2 Notes | Gastrointestinal Tract Notes)

extravillous cytotrophoblasts

(EVCTs) The trophoblasts which invade the uterine endometrium along with syncytiotrophoblasts and also secrete human chorionic gonadotropin hormone (hCG).
(More? Placenta Villi | Placenta Notes | Week 2 Notes)

exophytic

Histology/pathology term used to describe cellular growth beyond the surface epithelium from which the cells originates. Used to describe the type of growth seen in epithelial cancer (cervical cancer).

Extracorporeal Membrane Oxygenation

(ECMO) an invasive therapy that has been investigated and utilized in newborn infants with cardiorespiratory failure.
(More? Bookshelf - HSTAT)


eye field

Early embryonic region located at the anterior end of the neural plate and is the first indication of vertebrate optic development. Occurs initially a large single domain.

(More? Lecture - Vision | Development of Vision)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

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Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original F

F-factor

(fertility factor) A kind of episome in bacteria that can replicate either autonomously or in integrated form; can move from one bacterium to another during conjugation.

F1

(Latin, filial = son) first filial generation or the initial progeny of a cross-breeding (hybrid). The genetic breeding out (recombination) is said to strengthen the progeny, hence "F1 hybrid vigour".

F2

(Latin, filial = son) second filial generation The progeny of the F1 generation.

factor V Leiden

A mutation which is a heritable thrombophilia (increased tendency of blood to clot, impaired natural anticoagulant or fibrinolytic pathways) present in 5 - 8% of Caucasian populations.

falciform ligament

A sheet of parietal peritoneum between the two principal lobes of the liver. The ligamentum teres, the remnant of umbilical vein, lies within its folds.
(More? GIT Notes | Liver)

fallopian tube

(see uterine tube, uterine horn, oviducts) A pair of tubular structures designed to transport the oocyte (egg) from the ovary to the uterus body, named after Gabriel Fallopius (1523-1562), an anatomists and physician.

fecundity

(Latin, fecundus = "fertile") Clinical term used in reference to the ability to reproduce. Fecundity can be altered by both genetic and environmental factors.

femur length

An ultrasound measurement of Femur Length (FL) is used to determine fetal age and normal development (small/large/abnormal) parameters. The femur is the longest bone in the body and measurements and reflects the longitudinal growth of the fetus (approximately 14 weeks 1.5 cm - term 7.8 cm). It is one of the four typical ultrasound assessments of fetal size and age: Biparietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL).
(More? Ultrasound | Head Notes) | Fetal Notes | Birth Notes)

fenestra

(Latin, fenestra = "window") A small pore approximately 60 to 70 nm diameter in vascular bed endothelium (renal glomerular, gastrointestinal, and endocrine gland capillaries, corneal capillaries) allowing exchange between blood and tissues, plural - fenestrae.

fenestra ovalis

(Latin, fenestra = "window") (oval window) In the ear, the region that separates the tympanic cavity (middle ear) from the vestibule of the osseous labyrinth.

fenestra rotunda

(Latin, fenestra = "window") (round window) In the ear, the region that separates the tympanic cavity (middle ear) from the scala tympani of the cochlea.

fermentation

(Latin, fervere = "to boil") The anaerobic extraction of energy from organic compounds. The "boiling", or bubbling, is easily seen in the release of carbon dioxide from aerobic yeast during brewing processes.

fertility rate

A statisical term that refers to the total number of live births, regardless of age of mother, per 1,000 women of reproductive age, 15–44 years.
(More? Statistics | Australian Statistics)

fertilization

(fertilisation) The process of penetration of the oocyte (egg) by the spermatozoa and the combining of their genetic material that initiates development of the embryo. The union of two haploid gametes to form a diploid cell or zygote.
(More? 2009 Lecture - Fertilization | Week 1 Notes | Fertilization)

fertilization promoting peptide

(FPP) Also called Glu2TRH which is a small tripeptide (3 amino acid; pGlu-Glu-Pro-NH2) present in human seminal plasma which stimulates spermatozoa capacitation. Peptide is a structural analogue to thyrotrophin-releasing hormone (TRH; pGlu-His-Pro-NH2).
(More? Spermatozoa Capacitation | Spermatozogenesis)

fetal breathing movements

(FBM) Occur in the third trimester preparing both the skeletomuscular system and lungs mechanically for respiration.
(More? Respiratory Development - Birth | Respiratory Notes | Search Pubmed - fetal respiratory movements)

fetal death rate

A statisical term refers to the number of fetal deaths with a stated or presumed gestation of 20 weeks or more divided by the sum of live births plus fetal deaths, per 1,000 live births plus fetal deaths. Late fetal death rate shifts the stated or presumed gestational age to 28 weeks.
(More? Statistics | Australian Statistics | Search Pubmed - fetal death rate)

fetal fibronectin

(fFN) An extracellular matrix glycoprotein produced by fetal cells. Fetal fibronectin appears to act as an adhesive between the interface of the chorion and the decidua (fetal membrane and uterine lining). As a prenatal diagnostic test, a positive fetal fibronectin test result can indicate a higher risk of preterm delivery, but may also has false positive results.
(More? Prenatal Diagnosis | Normal Development - Birth | Birth - Premature)

Fetal Growth Restriction

(FGR) A term used to describe poor fetal growth and is also known as Intrauterine Growth Retardation.
(More? Intrauterine Growth Retardation)

Fetal Origins Hypothesis

(fetal programming hypothesis, Barker Hypothesis) Originally called the Barker Hypothesis, which began as statistical analysis carried out by Barker in the UK, of low birth weight data (early 1900's) and proposes in utero influences cause permanent changes in embryo/fetus, low birth weight, predisposition to chronic disease in adult life.
(More? Fetal Origins Hypothesis | Search Pubmed - fetal origins hypothesis)

fetal length

The measurement of crown to rump length of the developing fetus. The greatest growth in length occurs in the middle second trimester, of human development. There are a number of other growth parameters that can be measured, commonly determined by ultrasound, during the fetal period.
(More? Fetal | Ultrasound Measurements | Ultrasound Movies)

fetal period

(foetal period) In humans, the development week 9 to 36 is the fetal stage (second and third trimester) and during this time organs formed in the embryonic period continue to develop and the fetus grows in size and weight. The first 8 weeks of development is considered the embryonic period and is divided into 23 Carnegie stages based upon developmental milestones. Note when searching an alternate spelling "foetal".
(More? Fetal Notes | Embryo Stages)

fetal macrosomia

A clinical description for a fetus that is too large, condition increases steadily with advancing gestational age and defined by a variety of birthweights. In pregnant women anywhere between 2 - 15% have birth weights of greater than 4000 grams (4 Kg, 8 lb 13 oz) and can be associated with diabetes.
(More? Fetal Weight | Fetal Development | Birth)

fetal weight

The measurement of the weight of the developing fetus. The measurement is obtained by ultrasound calculation or clinically estimated by palpatation. The greatest addition of fetal weight occurs during and towards the end of the third trimester.
(More? Fetal Weight | Fetal Notes | Ultrasound Measurements | Ultrasound Movies)

fetotoxicant

A chemical that adversely affects the developing fetus, resulting in low birth weight, symptoms of poisoning at birth or stillbirth (fetus dies before it is born). Note when searching an alternate spelling "foetal".

(More?Abnormal Development - Environmental | Abnormal Development - Drugs)

fetus

(foetus) In mammals, term describes the period of development following the embryonic period. In humans, the development week 9 to 36 is the fetal stage (second and third trimester). (see fetal period above). This term is also used non-scientifically to describe the human conceptus at both embryonic and fetal stages of development.

FGR

Acronym for Fetal Growth Restriction a term used to describe poor fetal growth and is also known as Intrauterine Growth Retardation.
(More? Intrauterine Growth Retardation)

fibrillin

A connective tissue protein encoded in humans by (FBN1) gene which is associated with Marfan syndrome.
(More? Musculoskeletal Abnormalities)

fibrinoid layer

(Nitabuch's layer) A layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
(More? Placenta)

fibroadenomas

Term describing in relation to the breast, a lump, both smooth and firm, made up of fibrous and glandular tissue. These are generally not cancerous and are more common in younger women and may become tender in the days before a period or grow bigger during pregnancy.

fibroid embolization

The treatment method for uterine fibroids (non-cancerous tumor that can develop within the wall of the uterus) involving stopping or blocking the blood flow to the tumor.
(More? Human Menstrual Cycle | Genital System - Female Uterus | Urogenital Notes | Medline Plus)

fimbriae

(Latin, fimbria = a fringe) The finger-like projections at the ovarian end of uterine tube. At ovulation they sit over the ovary to aid egg movement into the uterine tube.
(More? Week 1 Notes)

Finasteride

A chemical used to prevent male pattern baldness and enlargement of prostate glands. An anti-androgen (blocks synthesis of dihydrotestosterone) and therefore a potential endocrine disruptor, exposed pregnant women can impact on male fetus genetial development.
(More? Endocrine Abnormalities)

first polar body

The small cytoplasmic exclusion body formed when the oocyte (egg) completes meiosis 1 at ovulation. This exclusion body contains the excess DNA from the first reductive division (the second and third polar bodies are formed from meiosis 2 at fertilization). These polar bodies do not contribute to the genetic complement of the zygote, embryo or fetus. Recent research in some species suggest that the space formed by the peripheral polar body (between the oocyte and the zona pellucia) can influence site of sperm fertilization.
(More? Week 1 Notes)

first trimester

Clinical term used to describe and divide human pregnancy period (9 months) into three equal parts of approximately three calendar months. The first trimester corresponds approximately to embryonic development (week 1 to 8) of organogenesis and early fetal. The second and third trimester correspond to the fetal period of growth in size (second trimester) and weight (third trimester), as well as continued differentiation of existing organs and tissues.
(More? Embryo Stages | Human Fetal Period | Development Week by Week)

fistula

An abnormal communication between 2 structures (organs, vessels, cavities) that do not normally connect.
(More? Head Abnormalities | Respiratory Abnormalities)

FL

Acronym for Femur Length, longest bone in the body, used in clinical ultrasound measurements and reflects growth of the fetus.
(More? Ultrasound Movies)

flagella

FLASH

Acronym for FLICE associated huge protein, a cytoplasmic component of the apoptosis signaling pathway which also translocates to nuclear Cajal bodies.

Flt1

Gene acronym for fms-like tyrosine kinase 1, one of the membrane receptors for vascular endothelial growth factor (VEGF). A soluble form of the receptor (sFlt1) inhibits VEGF signaling in the vasculature by competing with full-length Flt1 for binding to VEGF.

fms-like tyrosine kinase 1

(Flt1) One of the membrane receptors for vascular endothelial growth factor (VEGF). A soluble form of the receptor (sFlt1) inhibits VEGF signaling in the vasculature by competing with full-length Flt1 for binding to VEGF.

foetal

Often considered the British spelling, US spelling is actually more correct, "fetus" correctly derives from the Latin fetus see alternate spelling fetal period above.

Fog2

Acronym for Friend of Gata 2, a transcription factor required for diaphragm and lung development.

folic acid

(Latin, folium = leaf) (= Folate, Pteroylglutamic acid) A water soluble vitamin, found in many fruits (particularly oranges, berries and bananas), leafy green vegetables, cereals and legumes, which can prevent neural tube defects (NTDs). The cellular roles of folate include: DNA synthesis, amino acid metabolism and methylation of genes, proteins and lipids via S-adenosylmethionine-mediated one-carbon transfer reactions.
(More? Abnormal Development - Folic Acid and Neural Tube Defects | Neural System - Abnormal Development)

follicle

(Latin, folliculus = little bag, dim. of Latin follis) Term used in the structure of the ovary, in skin associated hair and within the thyroid gland. The functional unit within the ovary that includes the developing oocyte (egg) and the surrounding layers of cells that support that oocyte. Some cells within the follicle are released along with the ooctye at ovulation, while other cells are involved with female sex hormone secretion into the maternal bloodstream. The hair follicle is a specialized skin structure that forms the associated hair extending from the skin surface. In the endocrine thyroid gland the thyroid follicle is the histological unit structure of the thyroid gland.
(More? Week 1 - Oogenesis | Human Menstrual Cycle | Genital System - Female)

follicle atresia

The degeneration of the developing ovarian follicle, which can occur at any stage of follicular development. Many developing follicles undergo this process in each menstrual cycle.
(More? Week 1 - Oogenesis | Human Menstrual Cycle | Genital System - Female)

follicle stimulating hormone

(FSH, gonadotropin) Glycoprotein hormone secreted by anterior pituitary and acts on gametogenesis and other systems in both males and females. In females, FSH acts on the ovary to stimulate follicle development. Negative feedback by inhibin from the developing follicle decreases FSH secretion. In males, acts on the testis Sertoli cells to increase androgen-binding protein (ABP) that binds androgens and has a role in spermatogenesis. FSH-deficientcy in females results in infertile (block in folliculogenesis prior to antral follicle formation) and in males does not affect fertility (have small testes but are fertile). FSH protein has a molecular weight 30 kDa and a 3-4 hour half-life in circulation. Gonadotrophins have been used clinically in humans for the treatment of infertility. Other glycoproetin hormones include luteinizing hormone (LH), thyroid stimulating hormone (TSH), and chorionic gonadotropin.
(More? Week 1 - Oogenesis | Human Menstrual Cycle | Endocrine Development - Pituitary | PMID: 9020850)

follicular basal lamina

The basal lamina beneath the membrana granulosa (granulosa cell) layer of the developing follicles of the ovary. It separates the stratum granulosa from the thecal layers. Thought to be synthesized by granulosa cells, but may also have a contribution from the thecal layer.
(More? Week 1 - Oogenesis)

folliculin

(FLCN) A tumor-suppressor protein with unknown functions (see PNAS paper). Germ line mutations in the gene lead to Birt-Hogg-Dubé syndrome, characterized by benign tumors of the hair follicle, lung cysts, and renal neoplasia.
(More? OMIM folliculin | Birt-Hogg-Dubé syndrome | PNAS PMID: 17028174)

follicular fluid

The fluid found in the antrum of a secondary follicle. Secreted by cells in the wall of the follicle. This fluid is released along with the oocyte at ovulation.
(More? Week 1 - Oogenesis | Human Menstrual Cycle | Genital System - Female)

folliculogenesis

The term used to describe the process of follicle development within the ovary. The follicle is the structure developing within the ovary that includes the oocyte (egg) and surrounding support cells.
(More? Week 1 - Oogenesis | Human Menstrual Cycle | Genital System - Female)

fontanel

(fontanelle) A fibrous region between flat bones of developing skull. Have a role in birth allowing the cranial vault to flex and postnatally allow the skull to enlarge. In humans, there are six fontanels; an obvious anterior (bregmatic) and posterior (occipital) fontanels, as well the less noticeable lateral fontanels (two mastoid fontanels and two sphenoidal fontanels). A month or two after birth, the posterior and lateral fontanelles are lost, the anterior is not completely closed until about the 18 months.
(More? Musculoskeletal Development - Skull Development)

4 (four) dimensional ultrasound

(4D) A diagnostic ultrasound term used to describe the collection of three dimensional (3D) ultrasound images over time. These images can be assembled and played as a detailed movie.
(More? Ultrasound Movies)

foregut

The first of the three part/division (foregut - midgut - hindgut) of the early forming gastrointestinal tract. The foregut runs from the buccopharyngeal membrane to the midgut and forms all the tract (esophagus and stomach) from the oral cavity to beneath the stomach. In addition, a ventral bifurcation of the foregut will also form the respiratory tract epithelium.
(More? Gastrointestinal Tract - Stomach | Gastrointestinal Tract Notes | Respiratory Notes)

Forkhead Box F1

(Foxf1) A member of the forkhead gene family, a group of transcription factors originally identified in drosophila and have a role in development of the gall bladder and other tissues. The'forkhead' domain is a conserved 100 amino acid sequence.
(More? GIT Notes - Gall bladder | OMIM FORKHEAD BOX F1; FOXF1)

fourth ventricle

(4th ventricle) A fluid-filled space formed from neural tube lumen, located within the rhombencephalon (from the primary vesicle, hindbrain).
ANAT2341 Lecture - Ectoderm Development | Ventricular System | Notes)

Fraser syndrome

(cryptophthalmos-syndactyly syndrome) An autosomal recessive congenital malformation syndrome characterized by cryptophthalmos, syndactyly, and urogenital defects (bicornuate uterus, imperforate anus, anal stenosis or renal malformations).
(More? Eye Abnormalities | Limb Abnormalities | Urogenital Abnormalities | Urogenital Notes | OMIM - Fraser syndrome)

fundamental frequency

(natural frequency) The lowest audio frequency in a harmonic series, for the female voice this is about 225 Hz.

fusiform

(Latin, fusus = "spindle-shaped") widest near the middle and tapering in toward both ends, (back in the days of smoking) often described as "cigar-shaped". For example, used to describe the shape of the early developing stomach or the shape of smooth muscle cells.
(More? GIT Notes)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original G

G0

The state of a cell that has withdrawn from the cell cycle.
(More? Week 1 Notes)

G1

The period of the cell cycle that occurs after the completion of mitosis and before the beginning of DNA replication; also called the first growth phase.
(More? Week 1 Notes)

G2

The period of the cell cycle that occurs between the completion of DNA synthesis and before the beginning of mitosis (of the next cell cycle).
(More? Week 1 Notes)

galactorrhoea

An inappropriate milk production. Term is not used in relation to postnatal lactation where excess milk may be produced. Condition can occur in association with an anterior pituitary tumour producing prolactin (hyperprolactinemia).
(More? Endocrine Development - Pituitary | Normal Development - Milk)

galactosemia

An enzyme deficiency disorder. The enzyme galactose-1-phosphate uridyl transferase metabolizes galactose in milk sugar.
(More? Prenatal Diagnosis | Neonatal Screening | MedlinePlus - Galactosemia)

gall bladder

The septum transversum differentiates to form the hepatic diverticulum and the hepatic primordium, these two structures together will go on to form different components of the mature liver and gall bladder. In the adult, the gall bladder is a site of bile salt storage and concentration, to then be released into the small intestine where they act to solubilize dietary lipids by their detergent effect. Bile salts are a cholesterol derivative (breakdown product).
(More? Gastrointestinal Tract - Gall Bladder | Liver Notes | Gastrointestinal Tract Notes)

gametes

(Greek, gamos = marriage) A specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring; a sperm or an egg.
(More? Week 1 Notes)

gamete intrafallopian transfer

see GIFT
(More? In Vitro Fertilization Notes)

gameteogenesis

The production of either the haploid germ cells of spermatazoa (male) or eggs (female)
(More? Week 1 Notes)

gametophyte

The haploid form of a life cycle characterized by alternation of generations.
(More? Week 1 Notes)

gamma

Greek letter, ( capital letter gamma; lower case gamma) the lower case form used in scientific literature to designate different forms/variants of a similar protein, gene, energy form or substance.
(More? [greek.htm Greek Symbols])

gamma radiation

(Greek letter Γ capital letter gamma; γ lower case gamma) electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions which can be either mutagenic (DNA damage) or can cause serious cellular damage when absorbed by living cells.
(More? Abnormal Development - Radiation)

ganglion

The antomical ball formed by a group of peripheral neuron cell bodies (plural ganglia).

Gartner's duct

A female developmental abnormality caused by the persistance of the mesonephric duct (normally lost in females) when the ureteric bud fails to separate from the mesonephric duct. Can generate a broad ligament or vaginal cyst. Named after Hermann Treschow Gartner (1785-1827) a Danish surgeon and anatomist.
(More? Genital Abnormalities)

gastrointestinal tract

(GIT) The digestive tube extending from the oral cavity (mouth) to the anus. The digestive system includes the associated organs, which may also have other functions.
(More? GIT Notes)

gastroschisis

(omphalocele, paraomphalocele, laparoschisis, abdominoschisis, abdominal hernia) A developmental abnormality, which occurs as an abdominal wall defect associated with evisceration of the intestine.
(More? GIT Abnormalities | PMID:17230493 | PMID: 19419414)

gastrosplenic ligament

(gastrolienal ligament, ligamentum gastrosplenicum) Structure derived from the dosal mesogastrium (mesentery) connects the spleen to the stomach as part of the greater omentum.
(More? Spleen | GIT Notes)

gastrula

(Greek, gastrula = little stomach) A stage of an animal embryo in which the three germ layers have just formed.
(More? Gastrulation)

gastrulation

The process of differentiation forming a gastrula. Term means literally means "to form a gut" but is more in development, as this process converts the bilaminar embryo (epiblast/hypoblast) into the trilaminar embryo (endoderm, mesoderm, ectoderm) establishing the 3 germ layers that will form all the future tissues of the entire embryo. This process also establishes the the initial body axes.
(More? 2009 Lecture - Week 3 | Gastrulation)

GATA3

One of the GATA-binding protein family of zinc-finger transcription factors (recognize a consensus sequence known as the 'GATA' motif) involved in many aspects of embryo development. Expressed in white adipocyte precursors prior to diifferentiation and also to have a role in regulation of skin development through lipid biosynthesis.
(More? Integumentary Development | JCB - Skin Development | OMIM - GATA3)

GATA4

one of the GATA-binding protein family of zinc-finger transcription factors (recognize a consensus sequence known as the 'GATA' motif) involved in many aspects of embryo development. GATA4 and GATA6 activity interact to regulate gene expression in the developing cardiovascular system.
(More? Cardivascular Notes | Cardivascular Molecular | PNAS - Cardivascular Development | OMIM - GATA4)

GBS

Acronym for Group B Streptococcus

gene

A DNA sequence that is transcribed as a single unit and encodes a single polypeptide (protein) or a set of closely related polypeptides. There are approximately 20,000-25,000 protein encoding genes in the human genome. In each cell, DNA is found within the nucleus and also within mitochondria.
(More? DNA Notes)

genetics

The science of studying genes.
(More? DNA Notes)

genitalia

(Latin, genitalia = ) The term used to describe either the external or internal male and female sexual and reproductive organs.
(More? Urogenital Notes)

genital ridge

(= gonadal ridge) The thickened epithelial/mesenchymal region adjacent and medial too the mesonephros. Primordial sex cells migrate into this region to form the indifferent gonad. These undifferentiated gonads have a cortex and a medulla. Female XX chromosome complex, cortex differentiates into an ovary, and medulla regresses. Male XY complex, medulla differentiates into a testis and cortex regresses.
(More? Urogenital Notes)

genital tubercle

A prominence or rounded protuberance extending ventrally at the inferior end of the body of the embryo. It has initially a sexually indifferent external genitalia structure and contributes to either male (glans penis) and female (clitoris) external genitalia.
(More? Urogenital Notes)

genome

The collection of all the DNA in an organism.
(More? DNA Notes)

genomic imprinting

Epigenetics, expression of imprinted genes is monoallelic and dependent upon the parents sex (parental imprinting), in contrast most genes (which are non-imprinted) have biallelic expression. This is an heritable change that does not alter DNA sequence.
(More? Week 1 Notes)

genotype

The genes present in a particular organism or cell. In diploid cells, there are chromosome pairs each having a separate copy of every gene. In haploid cells, there is only a single copy of every gene.

germ layers

The first three cellular layers (ectoderm, mesoderm, and endoderm) that will form all tissues of the embryo. In humans, these layers begin to form during week 3 of development. Term should not be confused with germ cells, which are the oocyte and spermatazoa forming cells. Term originally used by Robert Remak (1815 - 1865), a German scientist and embryologist.
(More? Week 2 Notes Week 3 Notes | Robert Remak | Development Week by Week

germinal epithelium

The cuboidal epithelium component covering surface of ovary, it is continuous with mesothelium covering mesovarium. Note that it is a historical misnomer, as it is was thought to be the site of primordial germ cell formation, but is a covering epithelium with no role in primordial follicle formation.
(More? Week 1 - Oogenesis)

Germinal Matrix-Intraventricular Haemorrhage

(GM-IVH) in preterm infants most common form (up to 20% of preterm infants, less than 32 weeks gestation) of intracranial bleeding (haemorrhage).
(More? NZ National Women's Health GM-IVH)

germination

(Latin, germinare = to sprout) the resumption of growth by a seed.

gestation

The period of time from conception to birth. A pregnancy with multiple fetuses is referred to as a multiple gestation.

gestational age

The clinical term to describe human development timed from the last menstrual period (LMP) and therefore differs by approximately two weeks from research materials timed from fertilization.
(More? Development Week by Week)

gestational carrier

A woman who carries an embryo that was formed from the egg of another woman; the gestational carrier is expected to return the infant to its genetic parents.

gestational sac

A fluid-filled structure that forms within the uterus early in pregnancy. In a normal pregnancy, a gestational sac contains a developing fetus.

Gestational Trophoblastic Disease

mainly as a Hydatidiform Mole, (though there can be non-hydatidiform forms) tumour with "grape-like" placenta appearance without enclosed embryo formation, arises mainly from a haploid sperm fertilizing an egg without a female pronucleus.
(More? Week 1 Abnormalities | Week 2 Abnormalities)


gestational diabetes

(gestational diabetes mellitus, GDM) The form of diabetes occurring during pregnancy (5-6 % of singleton pregnancies, higher in twin pregnancies), where hormones can prevent insulin from working properly. Fetal (placental) regulation of maternal glucose levels usually allows support for fetal growth. Unregulated glucose levels can lead to fetal macrosomia. The mother usually reverts after the pregnancy, though this disease can be an indication of a risk of developing Type 2 diabetes later in lifef
(More? Maternal Diabetes | Medline - Diabetes Type 2 | Endocrine- Pancreas)

gestational trophoblastic neoplasia

(GTN) The development of the trophoblastic cell not containing an embryo, hydatidiform mole, which can be benign or malignant. Due to the continuing presence of the trophoblastic layer, this abnormal conceptus can implant in the uterus.
(More? Week 2 Abnormalities)

ghrelin

(Greek, leptos = thin) a polypeptide hormone produced in the gastrointestinal tract (stomach) that stimulates release of growth hormone from the anterior pituitary. Hormone which probably has a role in regulating appetite and energy balance.
(More? Endocrine Other Endocrine Notes | Meier U, Gressner AM. Endocrine regulation of energy metabolism: review of pathobiochemical and clinical chemical aspects of leptin, ghrelin, adiponectin, and resistin. Clin Chem. 2004 Sep;50(9):1511-25.

GHRH

Arconym for Growth Hormone Releasing Hormone, secreted by the Hypothalamus it is a protein that activates Growth Hormone synthesis and release from the pituitary.
(More? Endocrine Notes - Hypothalamus)

GIFT (gamete intrafallopian transfer)

A procedure that involves removing eggs from a woman's ovary, combining them with sperm, and using a laparoscope to assist in placing the unfertilized eggs and sperm into the woman's fallopian tube through small incisions in her abdomen. (More? Week 1 Notes)

glial cell

A cell within the nervous system that does not itself transmit electrical and chemical signals, but which provides metabolic and structural support for neurons. There are many different types of glial cells.
(More? Neural Notes)

glycodelin

a glycoprotein secreted from different tissues and in several glycosylated forms, it is a member of the lipocalin superfamily. Glycodelin-A is released from endometrial glands (into the uterine space) under progesterone regulation. Glycodelin from the placenta has an apparent immunosuppressive activity.

Globozoospermia

also called round-headed spermatozoa, is a human infertility syndrome caused by spermatogenesis defects leading to a malformed or absent sprematazoa acrosome. The acrosomal reaction being a key component of sperm fertilization of the egg.
(More? Week 1 Abnormalities | OMIM - Globozoospermia)

glottis

(Greek, = larynx) the boundary between pharynx to the larynx and consists of the vocal folds and their associated intervening space.
(More? Gastrointestinal Tract Notes | Respiratory Notes)

glucagon

A protein hormone produced in the pancreas; a signal for the postabsorptive state; glucagon inhibits glycogen synthesis and stimulates its breakdown into glucose.

glycocalyx

(Greek, glykos = sweet + Latin, calix = cup), also called the cell coat. A densely staining zone just out-side most eukaryotic cells.

glycolysis

(Greek, glykys = sweet, referring to sugar + Iyein = to loosen) A set of ten chemical reactions that is the first stage in the metabolism of glucose.

goitre

(goiter) The enlargement of thyroid gland due to a dietry deficiency of iodine, or thyroid hormone level abnormalities. Iodine is required to synthesise thyroid hormone which in turn is required for normal neurological development.
(More? Abnormal Development - Iodine Deficiency | Endocrine Development - Thyroid)

golgi apparatus

(Golgi complex) The cytoplasmic organelle within eukaryotic cells, involved in protein processing for the cellular processes of exocytosis (secretion) and endocytosis (absorbtion). The organelle consists of a set of membrane flattened discs, usually near the nucleus. In spermatazoa, the golgi apparatus apparatus is modified to form the acrosome.

gonad

(Greek, gonos = seed) A gamete-producing (germ cell) organ. A non-sexual term which is used to describe both the female ovary and male testis.
(More? Week 1 Notes)

gonadotrophin releasing hormone

(Greek, gonos = seed) (GnRH) Hormone released from hypothalamus that stimulates pituitary gonadotropin synthesis and secretion ([L.htm#luteinizing_hormone luteinizing hormone, LH] and [F.htm#follicle_stimulating_hormone follicle stimulating hormone, FSH]). The cyclic release of GnRH has been shown to differentially affect gonadotropin release (rapid frequency, more than 1 pulse / hour LH; slower frequencies FSH secretion).
(More? Week 1 Notes | Marshall JC, Eagleson CA, McCartney CR. Hypothalamic dysfunction. Mol Cell Endocrinol. 2001 Oct 25;183(1-2):29-32. Review.)

granulosa cell

A specific cell type that proliferates in association with the oocyte within the developing follicles of the ovary. These cells form the follicle stratum granulosa and are also given specific names based upon their position within the follicle. In the antral follicle, [M.htm#membrana_granulosa membrana granulosa] sits on the [F.htm#follicular_basal_lamina follicular basal lamina] and lines the antrum as a stratified epithelium. The [C.htm#cumulus_oophorus cumulus oophorus] is a column of granulosa cells that attaches the oocyte to the follicle wall. The [C.htm#corona_radiata corona radiata] are the granulosa cells that directly surround the oocyte, and are released along with it at ovulation. Following ovulation the corona radiata provide physical protection to the oocyte and granulosa cells within the ovulating follicle contribute to corpus luteum.
(More? Week 1 - Oogenesis | [week1_3d.htm Corpus luteum])

gravid

(Latin, gravidus gravis = heavy) To carry eggs.

gravidity

(Latin, gravidus gravis = heavy) The number of times a woman has been pregnant: gravida is a pregnant woman, nulligravida is a woman who has never been pregnant, primigravida is a woman who is pregnant for the first time, multigravida (secundigravida) is a woman who has been pregnant more than one time.

greater omentum

Splanchnic mesoderm peritoneal fold extending from the greater curvature of the stomach and hanging ventrally down "like an apron" in the peritoneal cavity over the small intestine. It forms initially in the embryo and fetus as a loop of the dorsal mesentery, which later fuses to form a single sheet attached to the posterior body wall. The [L.htm#lesser_omentum lesser omentum] is a smaller ventral peritoneal fold extending from lesser curvature of the stomach to liver.
(More? GIT Notes)

Greek Symbols

These symbols are used in scientific literature to designate different forms/variants of a similar protein or gene.
(More? [greek.htm Greek Symbols])

Gremlin

A 184-amino acid protein and bone morphogenic protein (Bmp) antagonist expressed during limb development in a region anterior to the zone of polarising activity (ZPA). Recent studies suggest that it acts as a signaling intermediate between sonic hedgehog (Shh) and fibroblast growth factor (Fgf). Belongs to the BMP antagonist gene family as Cerberus (head-inducing factor) and DAN (tumor suppressor)
(More? Musculoskeletal Notes - Limb Development | OMIM - Gremlin)

Gridlock

(grl) Name given to a zebrafish mutant and the related protein which generates cardiovascular system defects. The subsequent gene protein product "gridlock" is a transcription factor which has a role in determining artery/vein fate of lateral posterior mesoderm precursor cells.
(More? Blood Vessel | Zhong TP, Childs S, Leu JP, Fishman MC. Gridlock signalling pathway fashions the first embryonic artery. Nature. 2001 Nov 8;414(6860):216-20.)

growth hormone

(GH) A peptide hormone, made in the anterior pituitary, that stimulates tissue and skeletal growth. In the ovary, growth hormone also increases granulosa cell FSH-dependent E2 production.
(More? Endocrine Notes - Pituitary)

growth hormone releasing hormone

(GHRH) secreted by the hypothalamus it is a protein that activates Growth Hormone synthesis and release from the pituitary.
(More? Endocrine Notes - Hypothalamus)

Group B Streptococcus

(GBS) common bacteria in lower intestine of healthy adults (10 - 35%) also found in the vagina (13%) Women infected with no symptoms "colonized". This bacteria can also cause overwhelming infection and death.

growing pains

An intermittent aches or pains in legs that occur in the evening or at night occuring in children aged 3-12 years and may also occur during puberty growth.
(More? Child- Normal Development)

guanine

(guanine triphosphate) one of the 4 types (ATCG) of nucleotides that make up DNA. Base pairs with cytosine by 3 hydrogen bonds.
(More? DNA Notes)

Guthrie test

A newborn blood screening tes carried out for a variety of known genetic disorders. Blood is collected using a heel prick and spotted onto a test sheet to dry for later testing.
(More? Neonatal Screening)

gynecologist

(Greek, gyne = woman) doctor specializing in treating diseases of female reproductive organs.

gynecomastia

(Greek, gyne = woman, mastos = breast) is the excessive development of the male breast, which can occur transiently in puberty or due to other (hormonal) abnormalities.
(More? Integumentary Development - Mammary Glands)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original H

hair follicle

The hair forming complex structure within the skin with both epithelial and mesenchymal origins.
(More? Hair Notes | Skin Notes)

Hamburger Hamilton Stages

Chicken stages of development named after the 2 authors of a paper that divides the 21 days of chicken embryo development into 46 defined stages. These were published in: Series of Embryonic Chicken Growth. J. Morphology, 88 49 - 92 (1951).
(More? Chicken Embryo | Chicken Hamburger Hamilton Stages | Embryo Staging Systems)

haploid

(Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (egg, spermatazoa). Normally cells are diploid, containing 2 sets of chromosomes.
(More? DNA Notes)

hard palate

he bony anterior portion of the palate formed by maxillary and palatine bones. The muscular posterior portion is called the soft palate.
(More? Head Notes)

haustra

Term used to describe the colon recesses or sacculations caused by contractions of the teniae coli and circular muscle.
(More? GIT Notes)

haematocrit

The percentage by volume of red blood cells in blood.
(More? Blood Notes)

haemopoiesis

The term used to describe the process of blood cell formation/differentiation from blood stem cells. In the embryo, this is mainly red blood cell formation which begins in the yolk sac mesoderm, then the liver and other organs finally residing in the bone marrow.
(More? Blood Notes | Liver Notes)

HAND1

A gene encoding a basic helix-loop-helix (bHLH) transcription factor that is expressed in fetal and adult heart. In the mouse, Hand1 and Hand2 are expressed in the heart and some neural crest derivatives, and Hand1 is also expressed in extraembryonic membranes.
(More? OMIM: HAND1)

Hassall's bodies

(Hassall's corpuscles) Histological thymus structures that appear in fetal development and increase in number until puberty, then decreases. Named after Arthur Hill Hassall (1817-1894) a British physician and chemist.
(More? Endocrine Notes - Thymus)

haversian canal

The historic term used to describe histologically a small canal in bone microstructure that conducts blood and other substances. Named after Clopton Havers (1650-1702) an English physician and anatomist.
(More? Bone Notes)

HC

An acronym for the ultrasound measurement of Head Circumference.

hCG

An acronym for the hormone human Chorionic Gonadotrophin.

head circumference

An ultrasound measurement of Head Circumference (HC) is used to determine fetal age and normal development (small/large/abnormal) parameters. Measured as an ellipse in a horizontal section at the level of the thalamus and the cavum septi pellucidi. It is one of the four typical ultrasound assessments of fetal size and age: [B.htm#biparietal_diameter Biparietal Diameter] (BPD), Head Circumference (HC), [A.htm#abdominal_circumference Abdominal Circumference] (AC), and [F.htm#femur_length Femur Length] (FL).
(More? Ultrasound | Head Notes) | Fetal Notes | Birth Notes)

heart

An early developing organ which fuctions as a pump for blood in the embryo and adult. In the human, the heart development appears in week 4 within the splanchnic mesoderm as a simple tube. This tube then undergoes a series of growth, complex folding and reorganization to form the 4 chambered heart. There are many developmental abnormalities associated with heart development.
(More? heart | original Heart Notes)

heart field

hemangioblast

the common blood island progenitor cell which forms both hematopoietic (blood) and endothelial (blood vessel) cells.
(More? Blood Notes Blood Vessels)

hemimelia

(Greek, hemi = half, melia = limb) limb abnormality with the absence of half a limb, as described in the original classical classification of limb deficiencies.
(More? Limb Abnormalities - Classification)

hemotrophic nutrition

Term used to describe in late placenta development the transfer of blood-borne nutrition from maternal to embryo/fetus compared to early [#histiotrophic_nutrition histiotrophic nutrition].
(More? Placenta Notes | Uterine glands provide histiotrophic nutrition for the human fetus during the first trimester of pregnancy. Burton GJ, Watson AL, Hempstock J, Skepper JN, Jauniaux E. J Clin Endocrinol Metab. 2002 Jun;87(6):2954-9. PMID: 12050279 J Clin Endocrinol Metab.)

Hensen's node

(primitive node, primitive knot) See primitive node. forms the initial region at the cranial end of the primitive streak (where gastrulation occurs) and is a controller of this process. It is also the site of epiblast extension cranially to form the initial axial process. Region is equivilant to the blastopore in amphibians.
(More? Carnegie stage 7 | original Carnegie Stage 7 | Week 3 Gastrulation | Neural Notes | Nobel Laureate- Hans Spemann)

hepatic

(Greek, hepato = liver) Term used in relation to the liver and its associated structures.
(More? Gastrointestinal Tract - Liver)

hepatic duct

The liver excretory duct, joins with gall bladder cystic duct to form the common bile duct.
(More? Gastrointestinal Tract - Liver | GIT Notes)

hepatoblast

The undifferentiated liver progenitor cell formed initially from endoderm, which willlater form both hepatocytes and biliary cells.
(More? Gastrointestinal Tract - Liver | GIT Notes)

hepatocyte

The functional liver cell formed from hepatoblast differentiation (hepatoblasts form from endoderm).
(More? Gastrointestinal Tract - Liver | GIT Notes)

hepcidin

A peptide involved in iron homeostasis which is regulated by bone morphogenetic proteins (BMPs), cytokines belonging to the TGF- superfamily.

Herceptin

The commercial name for an antibody that attaches itself to HER2 on breast cancer tumors, inhibiting the tumor's ability to grow. Approximately 15 - 25 % of breast cancer patients have a gene mutation known as HER2-positive.

hermaphrodite

(Disorder of Sex Development, DSD) This historic terminology is no longer applied to abnormal sexual development and has been replaced with the term Disorders of Sex Development (DSD). Humans having both male and female reproductive organs, occurs in both male and female forms and mixed ovotesticular DSD.
(More? Reproductive System - Abnormalities)

hernia

A general discription of protrusion of an organ through a weak spot in the surrounding tissue. In normal development, herniated midgut, describes the gastrointestinal tract growth outside the abdominal wall prior to body wall growth. In abnormal development, abnormal protrusion of organs in the diaphragm, abdominal or groin areas (hiatal hernias or inguinal hernias).

herniated

The description of the process of protrusion of an organ through a weak spot in the surrounding tissue. In normal development, herniated midgut, describes the gastrointestinal tract growth outside the abdominal wall prior to body wall growth. In abnormal development, abnormal protrusion of organs in the diaphragm, abdominal or groin areas (hiatal hernias or inguinal hernias). Occurs normally in the development of the gastrointestinal tract when the midgut is initially herniated at the umbilicus during embryonic development.

Hertwig's epithelial root sheath

(HERS) A bilayered epithelial structure required for tooth root formation (root organization induction, biomineralization), which also interact with cranial neural crest derived ectomesenchyme to guide root development. The two layers have different embryonic origins; an ectodermal outer and inner enamel epithelium layer. Named after Oskar Hertwig (1849 - 1922) who identified in amphibia in 1874.
(More? 2009 Lecture - Integumentary Development | PMID: 19576204)

heterotroph

(Greek, heteros = other + trophe = nourishment) An organism that cannot derive energy from sunlight or from inorganic chemicals but must obtain energy by degrading organic molecules.

heterozygous

Having two different alleles for a single gene (in a diploid organism).

hiatus

(Greek, hiatum = to gape) anatomical description of a gap, cleft or opening.

Hib

Acronym for Haemophilus influenzae type b vaccine.
(More? Normal Development - Immunization)

HIF-1

A transcription factor that is one of the main regulators of homeostasis in human tissues exposed to hypoxia, due to inflammation and/or insufficient circulation.
(More? Respiratory Development)

High mobility group box 1 protein

(HMGB1) A protein that regulates the process of endochondral ossification. HMGB1 accumulates in the cytosol of hypertrophic chondrocytes at bone growth plates and is secreted to act as a chemoattractant for osteoclasts, osteoblasts, and endothelial cells. The protein has other functional roles within the cell nucleus.
(More? Bone Development Notes | Stage-Specific Secretion of HMGB1 in Cartilage Regulates Endochondral Ossification)

high risk pregnancy

Term relates to multiple pregnancies, previous pregnancy problem, health problem (either before or due to the pregnancy) and age (over 35 years). Examples of maternal health conditions leading to high risk pregnancy include: autoimmune disorders, cancer, diabetes, heart disease, high blood pressure, kidney problems and sexually transmitted diseases.

hilum

Term used to describe an anatomical depression in an organ where vessels and nerves enter or leave.

hindgut

The last of the three part/division ([F.htm#foregut foregut] - [M.htm#midgut midgut] - ===hindgut===) of the early forming gastrointestinal tract. The hindgut forms all the tract from the distral transverse colon to the cloacal membrane and extends into the connecting stalk (placental cord) as the allantois. In addition, a ventral of the hindgut will also form the urinary tract (bladder, urethra) epithelium.
(More? Gastrointestinal Tract Notes | Urogenital Notes)

Hirschsprung's Disease

(intestinal aganglionosis, aganglionic colon, megacolon, congenital aganglionic megacolon) Gastrointestinal tract abnormality due to a lack of enteric nervous system (neural ganglia) in the intestinal tract responsible for gastric motility (peristalsis). In general, its severity is dependent upon the amount of the GIT that lacks intrinsic ganglia, due to an earlier developmental lack of neural crest migration into those segments. Historically, Hirschsprung's disease takes its name from Dr Harald Hirschsprung (1830-1916) a Danish pediatrician (of German extraction).
(More? Gastrointestinal Tract Abnormalities | Neural Crest Abnormalities)

hirsutism

Term used to describe male pattern hair (terminal hair: long, coarse, and pigmented) growth in the female due to androgens. The condition affects 5-15% of women of reproductive age and may be ethnic or genetic, but may also relate to the gonadal abnormality of polycystic ovary syndrome. Androgens from the adrenal glands and ovaries increase hair growth by converting vellus hair (fine, unpigmented) to terminal hair in areas of the face, chest, and abdomen. This condition differs from generalised hair growth not exclusive to androgen sensitive areas (hypertrichosis).


(More? Polycystic Ovary Syndrome | Integumentary Development - Hair)

histiotrophic nutrition

Term used to describe in early placenta development the intital transfer of nutrition from maternal to embryo (histiotrophic nutrition) compared to later blood-borne nutrition ([#hemotrophic_nutrition hemotrophic nutrition]). Histotroph is the nutritional material accumulated in spaces between the maternal and fetal tissues, derived from the maternal endometrium and the uterine glands. This nutritional material is absorbed by phagocytosis initially by blastocyst trophectoderm and then by trophoblast of the placenta. in later placental development nutrition is by the exchange of blood-borne materials between the maternal and fetal circulations, hemotrophic nutrition.
(More? Placenta Notes | Uterine glands provide histiotrophic nutrition for the human fetus during the first trimester of pregnancy. Burton GJ, Watson AL, Hempstock J, Skepper JN, Jauniaux E. J Clin Endocrinol Metab. 2002 Jun;87(6):2954-9. PMID: 12050279 J Clin Endocrinol Metab.)

histogenesis

Term used to describe the structural and functional differentiation of organs and tissues.
(More? Fetal Development)

histology

histones

(Greek, histos = web) One of a set of small, positively charged proteins that bind to DNA in eukaryotic cells. Their role is to "pack" DNA strands into a smaller volume to form the chromosome.
(More? DNA Notes)

HIV

Acronym for Human Immunodeficiency Virus.

HLA

An acronym for Human Leukocyte Antigen

Hofbauer cells

Cells found within placental villi connective tissue. Have a role as macrophages of mesenchymal origin with potentially additional functions (remodeling, vasculogenesis, regulation of stromal water content).
(More? Placental Notes)

holoprosencephaly

In early neural development the forebrain prosencephalon fails to divide and develop into the two bilateral cerebral hemispheres. In humans, 1/250 first-trimester embryos can have this condition, live birth prevalence is 1/16,000. Dubourg C, Bendavid C, Pasquier L, Henry C, Odent S, David V. Holoprosencephaly. Orphanet J Rare Dis. 2007;2:8. PMID: 17274816

homeostasis

(Greek, homeo = like, similar + stasis = standing) Term used to describe the process of achieving a relatively stable internal environment. Often used in describing the changes required in the fetus to neonate transition following birth (parturition).
(More? Birth Notes)

homeotic mutation

A mutation that causes the cells of an embryo to give rise to an inappropriate structure in the adult, for example, to legs instead of antennae.
(More? Fly Notes)

homologous chromosomes

The two matching chromosomes that align during meiosis I.
(More? DNA Notes)

homozygous

Having two copies of the same allele (in a diploid organism).
(More? DNA Notes)

hormone

(Greek, hormao = "I excite or arouse") A substance, made and released by cells in a specific organ or structure, that moves throughout the organism and exerts specific effects on specific cells in other organs or structures.
(More? Lecture - Endocrine Development | Endocrine Notes)

Hox gene

Acronym from homeo box gene identified as a conserved region of protein sequence required for DNA specific binding. Hox proteins are transcription factors regulating gene activity within cells during development and differentiation, have an important role in "patterning" tissues during development. These are the mammalian counterpart of a Drosophila homeo domain gene, for example the antennapedia mutation.
(More? Molecular Notes | Fly Development)

HPV

acronym for Human papilloma virus, a group of more that 100 different viral strains. Detectable by pap smear
(More? CDC STD Facts - Human papillomavirus | Medline Plus Human Papillomavirus | Human Menstrual Cycle - PapSmear)

HSC

acronym for Haematopoietic Stem Cell (note alternate spelling Hematopoietic)
(More? Blood Notes)

human chorionic corticotropin

(human chorionic adrenocorticotropin, hCACTH) Placental hormone thought to have corticotropin (ACTH)-like activity, increasing maternal cortisol levels.
(More? Lecture - Placenta Development | Lecture - Endocrine Development | Placenta Notes)

human chorionic gonadotrophin

(hCG) Placental hormone initially secreted by cells (syncitiotrophoblasts) from the implanting conceptus during week two, supporting the ovarian corpus luteum, which in turn supports the endometrial lining and therefore maintains pregnancy. Hormone can be detected in maternal blood and urine and is teh basis of many pregnancy tests. Hormone also stimulates the onset of fetal gonadal steroidogenesis, high levels are teratogenic to fetal gonadal tissues.
(More? Placenta Notes | Week 2 Notes)

human chorionic somatomammotropin

(hCS, human chorionic somatommotropin, human placental lactogen, HPL) Placental peptide hormone, similar to pituitary growth hormone, secreted by placental syncytiotrophoblasts. Hormone level increases in maternal blood through pregnancy, decreases maternal insulin sensitivity (raising maternal blood glucose levels and decreasing maternal glucose utilization) aiding fetal nutrition. Has some weak growth hormone activity.
(More? Lecture - Placenta Development | Lecture - Endocrine Development | Placenta Notes | Integumentary Development - Mammary Glands)

human chorionic thyrotropin

(hCT) Peptide placental hormone, similar to anterior pituitary released thyroid stimulating hormone (TSH), which along with human chorionic gonadotrophin (hCG) is thought to act on maternal thyroid. There is little recent research published on this hormone, its level and activities.
(More? Lecture - Placenta Development | Lecture - Endocrine Development | Placenta Notes | Integumentary Development - Mammary Glands)

Human Immunodeficiency Virus

(HIV) The virus which leads to Acquired Immune Deficiency Syndrome (AIDS), a fatal disease that destroys the immune system's ability to fight off infection. HIV virus is capable of being transmitted from mother to fetus.
(More? Abnormal Development - Viral Infection)

human embryo

The term used in describing the first 8 weeks of human development following fertilization. Historically divided into 23 Carnegie stages and is the time of organogenesis. The following period defined as fetal development. :(More? Embryo Stages)
Legal definition (Australian Government):
"human embryo means a discrete entity that has arisen from either:
(a) the first mitotic division when fertilisation of a human oocyte by a human sperm is complete; or
(b) any other process that initiates organised development of a biological entity with a human nuclear genome or altered human nuclear genome that has the potential to develop up to, or beyond, the stage at which the primitive streak appears; and has not yet reached 8 weeks of development since the first mitotic division."

human leukocyte antigen

(HLA) human major histocompatibility complex.

human umbilical cord perivascular cells

Cells that surround the umbilical cord blood vessels and when isolated have been identified as a source of human mesenchymal stem cells. Described as umbilical cord derived mesenchymal progenitors (HUCPVCs) forming single-cell-derived (SCD) clonal populations.

humoral immunity

(Latin, umor = fluid) the production of antibodies by the immune system that recognise foreign material to the body.

Hutchinson–Gilford Progeria Syndrome

(HGPS) a rare genetic disorder characterized by dramatic premature aging. It occurs due to a point mutation in the gene for nuclear lamin A (LA) protein, required for normal nuclear structure, the mutation generates a mutant protein.
(More? Cao K, Capell BC, Erdos MR, Djabali K, Collins FS. A lamin A protein isoform overexpressed in Hutchinson-Gilford progeria syndrome interferes with mitosis in progeria and normal cells. Proc Natl Acad Sci U S A. 2007 Mar 14)

hyaluronan

(hyaluronic acid or hyaluronate) An extracellular matrix glycosaminoglycan disaccharide composed of D-glucuronic acid and D-N-acetylglucosamine. Has a role in embryonic development and in joint fluid, space filling role in resisting compressive forces. In oocyte development, hyaluronan is found in the cumulus extracellular matrix and has a role in the detachment of the cumulus-oocyte complex that becomes freely floating in follicular fluid before ovulation.
(More? Joint Development)

hydantoin syndrome

Term used to describe a fetal disorder caused by exposure of a fetus to the anticonvulsant drug phenytoin (Dilantin) used in the treatment of epilepsy.
(More? Abnormal Development - Drugs | Abnormal Development Notes | Medline Plus - phenytoin)

hydatid

Term used to describe "water".

hydrocele

(Greek, hydro = water, coele/koilia = cavity) a fluid-filled cavity of either testis or spermatic cord, where peritoneal fluid passes into a patent processus vaginalis.
(More? Genital Notes)

hydrocephalus

(Greek, hydro = water + cephalus = brain) developmental abnormality, rostral neural tube defect anterior neuropore fails to close leadin to a fluid-filled space rather than normal brain development.
(More? Neural Abnormalities)

hydrolysis

(Greek, hydro = water + lysis = breaking) Breaking the bond between two building blocks by adding a water molecule, reversing the dehydration-condensation reaction.

hydronephrosis

(congenital hydronephrosis, Greek, hydro = water) A kidney abnormality due to partial or complete obstruction at the pelvi-ureteric junction. This leads to a grossly dilated renal pelvis causing extensive renal damage before birth. This abnormality may be familial, may be lateral, and is most commonly an intrinsic defect in the wall of the ureter (structural or functional). The less severe cases may be salvaged by reconstruction of the pelvi-ureteric junction.
(More? [urogen2.htm#Congenital_Hydronephrosis Urogenital Abnormalities])

hydrophobic

(Greek, hydro = water + phobos = fear) Avoiding associations with water; nonpolar. The type of charge interaction which leads to the bilaminar structure of membranes where the nonpolar molecular "tails" face each other and polar "heads" are exposed to water.

hydrops fetalis

(Greek, hydro = water) accumulation of interstitial fluid (edematous) in the fetus resulting in utero or perinatal morbidity and mortality. The two main forms are immune (Rh incompatibility) or non-immune (disruption of fluid management).
(More? Medline Plus - hydrops fetalis)

hydrosalpinx

(Greek, hydro = water + salpinx = trumpet) accumulation of interstitial fluid (edematous) in either one or both blocked uterine or fallopian (salpinx refers to the trumpet shape of the uterine tube) tubes due to a previous tubal infection. This blockage can impact upon maternal fertility and require IVF for reproduction.
(More? ASRM - Hydrosalpinx Patient FactSheets PDF)

hygiene hypothesis

a relatively new theory (yet to be tested) that suggests that first world disease like asthma, inflammatory bowel disease, multiple sclerosis, and others may be due in part to lifestyle and environmental changes that make us too "clean" for our environment.

hyperbilirubinemia

Bilirubin is produced during red blood cell recycling and processed by the liver to be removed in the stool. Prenatally the placenta removes fetal bilirubin for maternal liver processing. High levels of bilirubin in the body can cause the skin to look yellow, [J.htm#jaundice jaundice].
(More? Medline Plus - Newborn jaundice)

hypernatraemic dehydration

A form of newborn dehydration associated with insufficient intake of milk. Blood sodium can increase and if not treated can lead to neurological, circulatory problems and death.

hyperplasia

An abnormal increase in organ due to cell proliferation.

hyperplastic rests

In kidney development, embryonic blastema cells can persist and proliferate to form a pool of cells, which under either genetic or epigenetic influence can then change to become a neoplastic rest. Normally the majority of nephrogenic rests either regress or become dormant.
(More? Wilm's tumour | nephrogenic rest | Urogenital Abnormalities | Urogenital Notes)

hyperthermia

Term used to describe a high core body temperature. This has been shown in animal models to be a potent teratogen.
(More? Abnormal Development- Hyperthermia)

hyperthyroidism

Clinical term describing an overactive thyroid gland.
(More? Thyroid Notes | Endocrine Notes)

hypoblast

The transient epithelium that forms during week 2 of human development that lines the blastoceol, and forms part of the bilaminar embryo (epiblast/hypoblast) from the inner cell mass. During trilaminar embryo development, the process of gastrulation replaces the hyoblast layer within the embryo with endoderm germ layer.
(More? Week 2 Notes)

hypochondroplasia

Clinical term describing mild skeletal dysplasia, due to a mutation in gene encoding fibroblast growth factor receptor-3 (FGFR3), the same gene mutated in the more severe limb Achondroplasia. Genetically heterogeneous, with some cases caused by mutation in genes other than FGFR3.
(More? Musculoskeletal Abnormalities | OMIM Hypochondroplasia | FGFR3)

hypodontia

Term describing a congenital absence of teeth.
(More? Integumentary Development - Tooth)

hypohydrosis

Term describing a diminished sweat gland function, and therefore decreased or lack of perspiration.
(More? Integumentary Development - Glands)

hypohidrotic ectodermal dysplasia

(HED) An abnormality of skin characterised by: sparseness of scalp and body hair, reduced ability to sweat and congenital absence of teeth. Occurs in three distinct forms: X-linked recessive (EDA gene), autosomal recessive forms (EDAR and EDARADD genes) and autosomal dominant form (EDAR and EDARADD genes).
(More? Integumentary Development - Glands | GeneReviews - Hypohidrotic Ectodermal Dysplasia)

hypopharyngeal eminence

(hypobranchial eminence) An early embryonic structure in the developing head. A narrow midline mesodermal (mesenchymal) exension lying within the floor curve of the developing pharynx. Fusion of 3rd pharyngeal arches and precursor of root of tongue. Early developing thyroid cells also migrate into this structure as cords of cells.
(More? Head Notes | Endocrine Development - Thyroid)

hypotrichosis

A decreased amount of of scalp and body hair.
(More? Integumentary Development - Hair)

hypophysis

(pituitary gland) Alternative name for the pituitary gland.
(More? Lecture - Endocrine Development | Pituitary Notes | Endocrine Notes)

hypospadia

A male external genital abnormality, which is the most common penis abnormality (1 in 300) resulting from a failure of male urogenital folds to fuse in various regions and are therefore classified by the location of the opening (meatus).
(More? Genital Abnormalities - Hypospadia | Genital Notes)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

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Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original I


ICSH

Acronym for Cell Stimulating Hormone an anterior pituitary hormone.
(More? Interstitial Cell Stimulating Hormone)

idiopathic

( Greek, idios = one's own + pathos = suffering) Term used clinically to describe a condition which is unexplained (obscure, unknown cause) or has no other clinical or biochemical associated abnormality.
(More? Abnormal Development)

ICSI

An acronym for IntraCytoplasmic Sperm Injection, A procedure in which a single sperm is injected directly into an egg; this procedure is most commonly used to overcome male infertility problems.
(More? Week 1 - In Vitro Fertilization | Week 1 - Spermatogenesis)

IHBD

An acronym for intrahepatic bile duct

ileum

Third part of small intestine lying between the jejunum and large intestine. (More? Gastrointestinal Tract Notes)

implantation

The term used to describe process of attachment and invasion of the [U#uterus|uterus] endometrium by the blastocyst (conceptus). Abnormal implantation is where this process does not occur in the body of the uterus (ectopic) or where the placenta forms incorrectly.
(More? Week 2 - Implantation | Week 2 Abnormalities)

incomplete abortion

previous term for retained products of conception where part of the placenta or fetal membranes remains within the [U#uterus uterus].

incus

One of 3 bones of the middle ear (stapes-malleus-incus) converts mechanical vibration into fluid movement within cochlea.
(More? Hearing Notes | Middle Ear)

induced abortion

(therapeutic abortion) A surgical, pharmaceutical or other medical procedure used to end a pregnancy.

induced pluripotent stem cell

(IPS cell) A reprogrammed adult stem cell to form an embryonic stem cell, from which tissues or whole animals can develop.
(More? Adult Stem Cells | Stem Cells)

induction

Developmentally, the term is used to describe the process by which one cell population influences the development of neighbouring cells.

Clinically or medically, the term is used to describe the process of artificially inducing labour.

(More? Birth Notes)

infantile hemangioma

(IH) One of the most common skin birthmarks appearing as a benign vascular neoplasm, not noted at birth but developing in the neonate and later postnatally. There are several known risk factors: female sex, white non-Hispanic race/ethnicity, and preterm birth. Though described as benign, a recent study has statistically linked these skin anomalies with low birth weight (LBW).
(More? Integumentary Development - Abnormalities | Abnormal Development | Birth - Low Birth Weight | PMID: 18940356)

infectious disease

(contagious disease) A bacterial, viral or fungal organism that is transferred from one organism to another by four main methods of transmission (contact, vehicular, airborne or vector). Contagiousness refers to the ease of transmission of the infective agent.
(More? Abnormal Development)

inferior

Anatomical term meaning below, beneath or lying below, a relative anatomical term.

infertility

Not fertile, unable to produce offspring.
(More? Week 1 Abnormalities)

infundibulum

The funnel-shaped initial segment of uterine tube (oviduct or Fallopian tube) opening into peritoneal cavity and connected to the ampulla. The peritoneal opening sitting over the ovary.
(More? Week 1 - Oogenesis | Genital System - Female)

inguinal canal

The anatomical pathway for male testes descent from the abdominal cavity (fetal) into the scrotum.
(More? Genital System - Male | Genital Notes - Gonadal Descent)

Inhibin A

A glycoprotein hormone is secreted by the corpus luteum and placenta and regulates pituitary follicle stimulating hormone (FSH). The hormone acts in negative feedback regulation of FSH during pregnancy. Measurement of Inhibin A levels is also used as a second-trimester maternal serum marker for Down syndrome.

Inhibin B

A glycoprotein hormone is secreted by early antral follicles during the luteo-follicular transition of the menstrual cycle and regulates pituitary follicle stimulating hormone (FSH).. In humans during the early follicular phase, high inhibin B concentrations allow the selection of a single follicle by decreasing the FSH serum levels.

iniencephaly

A fatal neural tube defect of initiation of neural tube closure at the level of the brain.
(More? Lecture - Neural Development | PMID: 19379086)


initial segment

(axon initial segment) Neuron cell body (soma) specialized cellular subdomain at the beginning of the axon, which during neuronal development excludes somatodendritic proteins from the axon and helps maintain neuronal polarity. This cytoplasmic region also contains unique cytoskeletal proteins (βIV spectrin and ankyrin G) involved in clustering voltage-sensitive sodium channels (Nav) at high density to enable action potential spike initiation and propagation.
(More?2009 Lecture - Late Neural Development)

inner cell mass

In a mammalian embryo, a small group of cells within a blastocyst that will eventually grow into the embryo itself and subsequently into the adult. The remainder of cells that form the wall are the trophoblast cells.
(More? Week 1 Notes | Week 2 Notes)

inner pillar cells

Within the organ of Corti cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. These cells have surface-associated microtubule bundles.
(More? Lecture - Hearing)

isthmus

(Greek, isthmus = narrow passage) Term used to describe an anatomical narrowing in a structure or tube.

insulin

A protein hormone, produced by specialized cells of the pancreas, that regulates glucose uptake; a signal for the absorptive state; promotes the synthesis of glycogen and inhibits its breakdown.
(More? Endocrine Development - Pancreas)

integument

(Latin, in = on, tegmen = a roof, covering) term used to describe the skin and its associated structures.
(More? Lecture - Integumentary | Skin Notes)

interatrial septum

(IAS) The wall (septum) that develops between the two atria in heart (cardiac) development. In the embryo, this septum develops as a sequence of mesenchymal structures bridging the left and right atrial opening (primary atrial foramen) forming a primary and secondary atrial septum.
(More? Heart Notes)

interferons

A cytokine that interferes non-specifically with the reproduction of viruses.

interferon-alpha

(IFNalpha) cytokine used to treat several malignant and nonmalignant diseases, especially hepatitis C.

interfollicular epidermis

(IFE) Term used to describe regions of the cellular (keratinocytes) outer layer of skin, the epidermis, lying between hair follicles. The keratinocyte epidermal cells are an ectoderm derived tissue.
(More? Integumentary Development)

interleukins

internal auditory meatus

(internal acoustic meatus, IAM) An anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur.
(More? Inner Ear - Internal Auditory Meatus | Hearing Development - Inner Ear | Sensory Development - Hearing)

interphase

The part of the cell cycle in which the chromosomes are not condensed and the cytoplasm is not dividing.

interstitial cell

(Leydig cell) Alternative name for Leydig cell found within the male gonad (testis). A cell that is involved in androgen (testosterone) production.
(More? Genital System - Male | Endocrine Development - Gonads)

interstitial cells of Cajal

(ICC) Neural cells located in the gastrointestinal tract (enteric nervous system) located within the smooth muscle wall (tunica muscularis) that act as electrical pacemakers to coordinate muscular slow wave contraction propagation. There is some evidence which suggests rather than neural crest, that these cells are mesenchymal (like gastrointestinal smooth muscle) in origin. There is also species variablity in plexus formation. In humans, interstitial cells of Cajal (ICC) myenteric plexus (ICC-MP) forms first, then intramuscular (ICC-IM) and deep muscular plexus (ICC-DMP) which are not fully differentiated at birth.
(More? Gastrointestinal Tract Notes)

interstitial cell stimulating hormone

(ICSH, gonadotropin, lutropin, Interstitial Cell Stimulating Hormone, ICSH) Glycoprotein hormone releasd from anterior pituitary hormone that acts on the gonad and has a role in male and female reproduction. In male, stimulates testis interstital cell (Leydig cell) production of testosterone. In female, increase in concentration during the menstrual cycle triggers ovulation (release of the oocyte).
(More? Endocrine Development - Gonads | Genital System - Male)

interstitial growth

The form of cartilage growth which occurs from within during development and leads to an increase of cartilage mass. The second form of cartilage growth is appositional growth, on the surface, and occurs mainly in the adult.
(More? Musculoskeletal Development)

Intrauterine Growth Retardation

Intrauterine Growth Retardation is a term used to describe poor fetal growth and is also known as Fetal Growth Restriction.
(More? Intrauterine Growth Retardation)

interventricular septum

(IVS) The wall (septum) that develops between the two ventricles in heart (cardiac) development. In the embryo, this septum develops as a sequence of mesenchymal structures bridging the left and right ventricular opening forming a membranous then muscular septum.
(More? Heart Notes)

interzone

A term used to describe in development of the musculoskeletal joint, the initial site of higher cell density found at the position of the future skeletal joint.
(More? Joint Development)

intestine

(bowel) Term used to describe the midgut and hindgut portion of the gastrointestinal tract running from after the stomach to the anus. This can also be anatomically subdivided into the small intestine (small bowel) and the large intestine (large bowel).
(More? Gastrointestinal Tract Notes)

intestinal aganglionosis

(Hirschsprung's Disease, aganglionic colon, megacolon, congenital aganglionic megacolon) Gastrointestinal tract abnormality due to a lack of enteric nervous system (neural ganglia) in the intestinal tract responsible for gastric motility (peristalsis). In general, its severity is dependent upon the amount of the GIT that lacks intrinsic ganglia, due to an earlier developmental lack of neural crest migration into those segments. Historically, Hirschsprung's disease takes its name from Dr Harald Hirschsprung (1830-1916) a Danish pediatrician (of German extraction).
(More? Gastrointestinal Tract Abnormalities | Neural Crest Abnormalities)

intestinal immune system

System consists of gastrointestinal tract functional regions and cells including: Peyer's patches, isolated lymphoid follicles, cryptopatches and mesenteric lymph nodes.
(More? Gastrointestinal Tract Notes | Immune Notes)

intracytoplasmic sperm injection

(ICSI) A procedure in which a single sperm is injected directly into an egg; this procedure is most commonly used to overcome male infertility problems.

(More? Week 1 - In Vitro Fertilization | Week 1 - Spermatogenesis)

intraembryonic coelom

The "horseshoe-shaped" space (cavity) that forms initially in the third week of development in the lateral plate mesoderm that will eventually form the 3 main body cavities: pericardial, pleural, peritoneal. The intraembryonic coelom communicates transiently with the extraembryonic coelom.
(More? Coelom Notes | Week 3 Notes)

intraflagellar transport

(IFT) process by which cilia containing microtubules are formed on cells. Recent research has shown an important roles for cell cilia in different systems during embryonic development.

intramembranous ossification

The term used to describe the process of replacement of a membranous mesenchyme with bone by osteoblasts (bone-forming cells). Mesenchymal cells (osteoprogenitor cells) differentiate into osteoblasts at the initial sites of ossification (ossification centre). Occurs in skull (jaw, cranial vault) and clavicle. The majority of the skeleton is formed by ann alternative process of bone formation on a cartilaginous template, endochondral ossification.
(More? Musculoskeletal Development - Bone | Musculoskeletal Notes)

intrahepatic bile ducts

(IHBDs) transport bile secreted from hepatocytes to the hepatic duct. The cells that line the IHBD are biliary epithelial cells generated from bipotent hepatoblasts around the portal vein.
(More? GIT Notes - Liver | GIT Notes - Gall Bladder)

intrapartum

The time in between the beginning of labor and delivery at birth (parturition).
(More? Birth Notes)

intrauterine

Term means lying within the uterus.

intrauterine growth restriction

(IUGR) Term used to descibe clinically a fetus that has not reached its growth potential because of genetic or environmental factors. Abnormal development measured as less than 10th percentile for gestational age, not easy to detect before 32 weeks. This poor fetal growth can have fetal, placental or maternal causes.
(More?Abnormal Notes IUGR | Fetal Weight | Fetal Length | Fetal Notes | Fetal Programming Hypothesis | Medline Plus - IUGR)

in vitro

(Latin, vitro = glass) In a test tube, used to describe any process that does not occur in its natural environment (in vivo). In development, often associated with In Vitro Fertilization (IVF).

in vitro fertilization

IVF, a procedure that involves removing eggs from a woman's ovaries and fertilizing them outside her body. The resulting embryos are then transferred back into the woman's [U#uterus uterus] through the cervix.
(More? Week 1 - In Vitro Fertilization | Week 1 - Fertilization)

in vivo

(Latin, vivo = life) Term used describe any process that occurs in its natural (normal) environment.

in vivo fertilization

The natural biological mechaism of [F#fertilization|fertilization] that occurs within the body.
(More? Week 1 - In Vivo Fertilization | Week 1 - Fertilization)

inotropes

Drugs that increase the force of cardiac contraction by acting on the autonomic nervous system.
(More? Heart Notes)

Iodine

(Greek, ioeides = violet) An element named for the color of its vapour. It is an essential element required for the synthesis of thyroid hormone, which in turn is required for normal neural development.
(More? Abnormal Development - Iodine Deficiency)

ischemia

A lack of oxygen in a tissue or organ due to decreasd blood flow by any mechanism (obstruction, narrowing or damage to blood vessels). Leads to hypoxia in the tissue.

islets of Langerhans

A small cell clusters spread throughout the exocrine pancreas with an endocrine (hormonal) function.
(More? Endocrine Development - Pancreas)

isolated levocardia

(IL) A rare (1 per 22 000 births) situs anomaly where there is a normal heart position (left-sided heart, levocardia) and a dextro position (right-side) of the abdominal viscera.
(More? Gastrointestinal Tract Abnormalities | Heart Abnormalities)

isthmus

(Greek, isthmos = a narrow passage, a land-bridge, a connecting band) A term used to describe anatomical structures with a similar physical structure. Uterine isthmus is the region between the uterine body (corpus) and the cervix.

IUGR

An acronym for IntraUterine Growth Restriction or Retardation, described as less than (<) 10th percentile for gestational age, not easy to detect before 32 weeks.
(More? Abnormal Notes IUGR | Fetal Programming Hypothesis)

IUI-donor

An acronym for Intra-Uterine Insemination using donated sperm.
(More? Week 1 - In Vitro Fertilization)

IVF

Acronym for In Vitro Fertilization, a procedure that involves medical intervention in the normal fertilization process. There are currently many different ways in which fertilization may occur using these clinical techniques. For example, removing eggs from a woman's ovaries, fertilizing them outside her body, then transferring back into the woman's [U#uterus|uterus] through the cervix.
(More? Week 1 - In Vitro Fertilization | Week 1 Notes)


Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original UNSW Embryology Glossary J

Jagged1

ligand for the Notch cell surface receptor. Has an important role in blood vessel development. Signal activation leads to cleavage of the intracellular part of the Notch receptor from the membrane which translocates to the nucleus and activate s transcription factors.
(More? [/heart19.htm Cardiovascular System - Blood Vessels] | [/heart11.htm Cardiovascular System - Molecular] | OMIM - Jagged1 | Pubmed - Jagged1 is required for vascular smooth muscle development)

JAK

acronym for "just another kinase" a kinase family involved in signal transduction.
(More? Molecular Development)

jaundice

Yellow colouration of the skin caused by high levels of bilirubin in the body. Present to some extent in most newborns due mainly to the time taken for the newborn liver to develop and functionally process bilirubin. Jaundice can also occur with normally with breast feeding (breastfeeding jaundice) and abnormally as a sign of a range of newborn abnormalities (conditions increasing red blood cell number or interference with bilirubin processing/removal).
(More? Medline Plus - Newborn jaundice)

JAWS

acronym for "Joints Abnormal With Splitting" a protein in mouse musculoskeletal development which coordinates cartilage formation and synovial joint positioning.
(More? [skmus31.htm Musculoskeletal - Joints] | Molecular Development)

jejunum

(Latin, jejunus = empty of food) Second part of the small intestine extending from the duodenum to the ileum.
(More? GIT Notes)

Joints Abnormal With Splitting

(JAWS) a protein in mouse musculoskeletal development which coordinates cartilage formation and synovial joint positioning identified in digit formation.
(More? [skmus31.htm Musculoskeletal - Joints] | Molecular Development)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original K

Kangaroo Mother Care

(KMC) or Kangaroo care (KC) began in Bogota (Colombia) in 1978. It is therapeutic skin-to-skin contact between an infant and parent where the infant is usually held chest-to-chest in an upright prone position. A Cochrane Database review concluded: "Although KMC appears to reduce severe infant morbidity without any serious deleterious effect reported, there is still insufficient evidence to recommend its routine use in LBW infants. Well designed randomized controlled trials of this intervention are needed." PMID: 12804436.
(More? Neonatal Notes)

karyoplast

(Greek, karyon = kernel or nucleus) Stem cell term describing a nucleus isolated from a eukaryotic cell surrounded by a very thin layer of cytoplasm and a plasma membrane.

karyotype

(Greek, karyon = kernel or nucleus + typos = stamp) Term used to describe the chromosomal (genetic) makeup (complement) of a cell.
(More? Week 1 Notes | Genetic Abnormalities)

keratin

An intermediate filament protein of the cell cytoskeleton. There are many different keratins with different tissue expression profiles. The most common is often identified in skin and mutations in this gene lead to skin defects.

kidney

In humans the metanephros forms the final adult kidney. An excretory organ which also has endocrine functions.
(More? Urogenital Notes)

ketosteroids

A 17-ketosteroid is the excreted inactive derivative (breakdown product) of testosterone formed by conjugation in the liver.
(More? Endocrine Notes)

knock out mice

A term used to describe the molecular biology technique of introducing a germ line gene specific disruption that results in mice that do not produce the protein product of that gene, it has been "knocked out". Technique required the development of stem cells to carry out the manipulation.

(More? Stem Cell Notes | Molecular Notes | Mouse Notes)

koilocytes

A visibly human papillomavirus (HPV) infected epithelial cells.
(More? Womens Health Issues - HPV)

Kolliker's organ

(Kollicker's organ, greater epithelial ridge) Developing cochlear structure consisting of columnar-shaped supporting cells filling the inner sulcus and lying directly under the tectorial membrane. This transient organ regresses and generates the space of the inner sulcus. Named after Rudolph Albert von Kolliker (1817-1905).

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original L

labyrinth

(Greek, labyrinthos) Term used to describe the complex inner ear system of fluid-filled passages which provides the sense of balance (semicircular canals, vestibule), the membranous labyrinth. Named by analogy with the Greek mythology maze that imprisoned the Minotaur.
(More? 2009 Lecture - Hearing Development)

lactation

(Latin lactans = suckling) production of milk through action of prolactin and other hormones on breast tissue. Therefore associated mainly with mammals.
(More? Normal Development - Milk | Integumentary Development - Mammary Glands)

lacuna

Anatomical and histological description of a small pit or cavity. Often used to describe the maternal blood-filled spaces formed during placenta development, maternal lacunae.
(More? 2009 Lecture - Placenta)

lacunae

A blood-filled spaces within endometrium, formed following blastocyst implantation and trophoblast erosion of the maternal sinusoids.
(More? Week 2 Notes | Placenta Notes)

lanugo

A fine coat of body hair found on the fetus.
(More? Integumentary Development | Integumentary Development - Hair)

lamellae

A term describing the concentric layers of bone.
(More? Musculoskeletal Notes)

lamina

A term describing a thin layer or sheet.

lamina propria

The layer of loose connective tissue underneath the epithelium of mucosa.

laparoscopy

A surgical procedure in which a fiber optic instrument (a laparoscope) is inserted through a small incision in the abdomen to view the inside of the pelvis.

large intestine

The region of the gastrointestinal tract lying between the end of the ileum (cecum) and anus. The large intestine can be further subdivided into parts: cecum, colon (ascending, transverse, descending, and sigmoid), and rectum. Functions in the resorption of water, vitamin K metabolism, and the formation of faeces.
(More? 2009 Lecture - Gastrointestinal Development | Gastrointestinal Tract Notes)

laryngeal webs

(congenital laryngeal webs) Laryngeal abnormality due to embryonic (week 10) incomplete recanalization of the laryngotracheal tube. Rare abnormality occuring mainly at the level of the vocal folds (glottis).
(More? Respiratory Abnormalities)

laryngotracheal groove

Early embryonic foregut developmental feature, forms on the anterior (ventral) wall of pharynx and gives rise to larynx, trachea, respiratory tree.
(More? Respiratory Notes | Head Notes | Stage 13/14 Embryo Section B3 Section B4)

larynx

Site of the the vocal folds in the neck. Embryologically develops from the foregut with the lining derived from endoderm and the cartilage from pharyngeal arch 4 and 6. Beginning as a simple foregut groove, the [L.htm#laryngotracheal_groove laryngotracheal groove] which folds to form the laryngotracheal bud, then the larynx and trachea.
(More? Gastrointestinal Tract NotesRespiratory Notes | Head Notes)

last menstrual period

(LMP) Clinical term used to describe the menstrual period that occurs before a pregnancy and is used as the date to calculate clinical pregnancy development (gestational age). Note that in humans this is approximately two weeks different from embryonic development, which begins at fertilization around the mid-point of the menstrual cycle.
(More? 2009 Lecture - Cell Division/Fertilization)

late-gestation lung protein 1

(LGL1) a glycoprotein secreted by fetal lung mesenchyme and fetal kidney, involved in retinoic acid stimulated branching morphogenesis. (PMID: 17670908)
(More? Respiratory Notes)

lateral

An anatomical description for away from the midline (paired with medial, towards the midline).

lateral cervical anomaly

(branchial cleft anomaly) Abnormality which can be four different types: first, second, third and fourth.
(More? Head Notes - Abnormalities)

lateral meningocele

A neural tube defect where herniation of the meninges occurs through a dilated neural foramina. One of the three classes of spinal meningocele (simple, lateral and anterior sacral meningocele).
(More? Neural Abnormalities | Neural Notes)

lead

An environmental heavy metal linked to developmental defects.
(More? Defects - Chemical Notes | Defects - Heavy Metals )

lectins

Class of carbohydrate-binding proteins originally found in plants. Can be used to specifically bind/identify glycoproteins.

Lee-Boot Effect

Reproductive change in female mice housed together (in groups) results in a synchronization of their estrus cycles. In addition, the extended absence of male pheromones leads to a state of anestrus (lack of a normal estrus cycle).
(More? Mouse Development- Estrous Cycle

leiomyoma

(uterine fibroids) A benign smooth muscle tumor of the uterus. These are also one of the most common gynecologic neoplasm in women, often detected on pelvic examination or by a range of diagnostic tools (endovaginal sonography, sonohysterography, hysterosalpingography, magnetic resonance imaging, computerized tomography, radionucleotide scanning, serum markers). The condition is difficult to distinguish from another uterine disease adenomyosis.
(More? Reproductive System - Abnormalities | Medlineplus - uterine fibroids)

leptin

(Greek, leptos = thin) a polypeptide hormone (16 kDa) produced in adipose and many other tissues. Hormone receptor (OB-R, leptin receptors) found in many different tissues. Hormone levels associated with fertility and reproductive maturity in many species. Other hormonal roles include: satiety, adiposity, and metabolism, body mass control, angiogenesis, immunity, wound healing, bone remodelling cardiovascular function, and specific metabolic pathways.
(More? Endocrine Adipose Endocrine Notes | Henson MC, Castracane VD. Leptin in pregnancy: an update. Biol Reprod. 2006 Feb;74(2):218-29.)

lesser omentum

The smaller of two splanchnic mesoderm peritoneal folds (lesser/greater), the lesser extends from lesser curvature of the stomach to liver. The [G.htm#greater_omentum greater omentum] extends from the greater curvature of the stomach and hanging down "like an apron" ventrally over the small intestine.
(More? 2009 Lecture - Gastrointestinal Development | GIT Notes)

levonorgestrel

A synthetic progesterone used in oral contraceptives and as an emergency contraceptive. (Other Progestins: 3-keto-desogestrel, dienogest, drospirenone, Nestorone, nomegestrol acetate and trimegestone) Note that Trimegestone and Nestorone are currently the most potent fourth-generation progestins with no androgenic or estrogenic actions.
(More? Human Menstrual Cycle)

Leydig cells

(interstitial cells) Testis (male gonad) cell which secrete testosterone, beginning in the fetus. These cells are named after Franz von Leydig (1821 - 1908) a German scientist who histologically described these cells.
(More? 2009 Lecture - Genital Development | Genital Notes | Urogenital Notes)

Leydig cell hypoplasia

(LCH) or male pseudohermaphroditism is an autosomal recessive disorder in individuals with a 46,XY karyotype with a predominantly female phenotype
(More? Hermaphroditism | Reproductive System - Abnormalities)

leukocyte

(Greek, leukos = clear, white) white blood cell.

LGL1

acronym for Late-Gestation Lung Protein 1, a glycoprotein secreted by fetal lung mesenchyme and fetal kidney, involved in retinoic acid stimulated branching morphogenesis. (PMID: 17670908)

ligamentum arteriosus

The postnatal ligament remnant structure formed from the ductus arteriosus, a prenatal vascular shunt.
(More? Cardiovascular Notes)

ligamentum teres

(ligamentum teres uteri, Hunter's ligament) The round ligament of uterus which maintains the ventral uterine position.

ligamentum venosus

The postnatal ligament remnant of the ductus venosus, a vessel which prenatally connects (shunts) the portal and umbilical veins to the inferior vena cava and also acts to protect the fetus from placental overcirculation.
(More? Cardiovascular Notes)

ligand

(Latin, ligare = to bind) A molecule that binds to a specific binding site in a protein.

Lim

Acronym for LIM domain proteins were named after the worm proteins (===Li===n11 and ===M===ec3) and vertebrate protein which specify cell lineage and organ development (also involved in cytoskeleton organization and oncogenesis). Ldb genes encode LIM domain-binding (Ldb) factors and have been identified as a regulator of neural tube differentiation at the spinal cord level (Lim hox gene expression).
(More? Other Embryo - Worm)

limb-girdle muscular dystrophy type 2A

(LGMD2A) Human recessive genetic disorder caused by mutations in the calpain 3 (CAPN3) gene.

lin-35

(lin-35 Rb) A retinoblastoma tumor suppressor (Rb) related gene in worm C. elegans, identified as a synthetic multivulva (synMuv) class B gene.
(More? Other Embryo - Worm)

Lingo/LERN

(Leucine-Rich Repeat Neuronal Protein, LRRN6A) gene family encoding type 1 transmembrane proteins, with 12 extracellular leucine rich repeats, an immunoglobulin C2 domain and a short intracellular tail. Expressed in neural and nonneronal developing tissues: developing cranial ganglia (trigeminal, facio-acoustic) and dorsal root ganglia, somites (dermomyotome), spinal cord (motor horn), otic vesicle and developing gut epithelium.
(More? Neural Notes | OMIM - Leucine-Rich Repeat Neuronal Protein | Haines BP, Rigby PW. Expression of the Lingo/LERN gene family during mouse embryogenesis. Gene Expr Patterns. 2008 Jan;8(2):79-86.)

lingual

(Latin, lingua = tongue) Term used to describe structures and features related to the tongue: lingual papilla, lingual plate, lingual plexus, lingual thyroid nodule.
(More? Tongue Notes | Head Notes)

lipophorin

(Lp) lipoprotein particle formed in insect cells that has been identified as having a role in Hedgehog (Hh) signaling during development. Lipophorins (Lp) contain two apolipophorins I and II (ApoLI and ApoLII). Similar lipoprotein particles can be found in vertebrates and consist of a phospholipid monolayer surrounding a core of esterified cholesterol and triglycerides which is scaffolded by apolipoproteins. Reference: Callejo A, Culi J, Guerrero I. Patched, the receptor of Hedgehog, is a lipoprotein receptor. Proc Natl Acad Sci U S A. 2008 Jan 15
(More? Molecular Development - Sonic Hedgehog | Molecular Development - Patched Receptor)

lissencephaly

(smooth brain) A developmental brain abnormality resulting from an absence (agyria) or the paucity (pachygyria) of cerebral convolutions, caused by defects in neuronal migration by the gene LIS1. Two major types: Miller–Dieker syndrome (MDS) and isolated lissencephaly sequence (ILS).
(More? Neural Notes | Fetal Neural)

listeria

A large family of bacteria found throughout the environment (soil, dust, water, unwashed raw produce, fish, undercooked poultry, prepared meats such as hot dogs and deli meats, and faeces of domestic and wild animals). Listeria monocytogenes is the specific bacteria form that causes the infection "listeriosis". The most common human source of infection is contaminated foods: delicatessan meats, unpasteurized milk or dairy products, soft cheeses, and paté. Once infected, Listeria lives in the gastrointestinal Maternal listeriosis with symptoms has a risk (2-14 days after maternal infection) of for miscarriage, stillbirth, uterine infection, premature labor, and death in the newborn period.
(More? Abnormal Development)

Littre hernia

(hernia of the Meckel diverticulum) The protrusion of a Meckel diverticulum through a potential abdominal opening. The hernia sites are: inguinal (50%), umbilical (20%), and femoral (20%). Named after Alexis de Littre (1700) who initially reported ileal diverticula.
(More? GIT Abnormalities)

live birth

The delivery of one or more babies with any sign of life. World Health Organization (WHO) definition: "Live birth is the complete expulsion or extraction from its mother of a product of conception, irrespective ot the duration of pregancy, which, after separation, breathes or shows evidence of life, such as the beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached; each product of such a birth is considered liveborn."

liveborn

See the term live birth definition above.

LMP

Acronym for Last Menstrual Period that occured before a pregnancy and is used as the date to calculate clinical pregnancy development (gestational age).

lobule

Term used to describe a small lobe. Can be used to describe part of a gland, ear, organ structure.

lunatic fringe

A gene encodes a secreted signaling protein that signals formation of boundaries between groups of cells during development. One mechanism is by modifying Notch and inhibits signaling through the Notch pathway. In neural tube, regulates early neural crest differentiation. In mesoderm, regulates somite formation (segmentation).
(More? Neural Crest - Molecular | Molecular Development - Notch | OMIM - lunatic fringe)

lung bud

The term describing the primordia of lung development. Foregut endoderm branches into the surrounding visceral mesoderm, forming the trachea, which brances again into the bronchi and thsi process is repeated over and over again through development. Establishing the major respiratory branches first, followed by minor branches, then terminal branches, then immature alveoli which later mature to form teh functional end structures of the lung.
(More? Respiratory Notes)

luteinizing hormone

(LH, gonadotropin, lutropin, Interstitial Cell Stimulating Hormone, ICSH) Glycoprotein hormone releasd from anterior pituitary hormone that acts on the gonad and has a role in male and female reproduction. In female, increase in concentration during the menstrual cycle triggers ovulation (release of the oocyte). In male, stimulates testis interstital cell (Leydig cell) production of testosterone. Gonadotrophins have been used clinically in humans for the treatment of female infertility.
(More? Human Menstrual Cycle | Genital Notes)

lutenizing hormone

alternative spelling, (LH, gonadotropin) (LH, gonadotropin, lutropin, Interstitial Cell Stimulating Hormone, ICSH) Glycoprotein hormone releasd from anterior pituitary hormone that acts on the gonad and has a role in male and female reproduction. In female, increase in concentration during the menstrual cycle triggers ovulation (release of the oocyte). In male, stimulates testis interstital cell (Leydig cell) production of testosterone.
(More? Human Menstrual Cycle | Genital Notes)

luteinizing hormone/chorionic gonadotropin receptor

(LHCGR) a G protein-coupled receptor expressed in male testis (Leydig cells) and female ovary (granulosa-lutein and theca cells)
(More? Genital Notes)

Lyme disease

Caused by a bacterium, Borrelia burgdorferi, which was cultured from the midgut of Ixodes ticks in the mid-1980s. Named after a small town of Lyme in Connecticut where in the mid-1970s this diesease was initially identified.
(More? NCBI Coffee Break Lyme Disease)

lymphangiogenesis

development or growth of lymphatic vessels.
(More? Lymphatic Notes)

lymphangioma

a disfiguring vascular malformation of early childhood (mostly before 2 years of age) occuring in soft tissues of the head and neck or axilla, may also occur in the limbs, trunk, viscera and serous cavities.
(More? Lymphatic Notes)

lymphedema

abnormal accumulation of interstitial fluid in tissues due to a lack of lymphatic drainage, which in turn leads to localized swelling.
(More? Lymphatic Notes)

lymphopoiesis

(lymphoid hematopoiesis, lymphocytopoiesis) the process of generating lymphocytes (the immune cells) in various tissues (bone marrow, lymph nodes, thymus and spleen).
(More? Blood Notes | Lymphatic Notes)

lyssavirus

A form of virus closely related to classical rabies (though genetically and serologically distinct). A form of this virus carried in bats (Australian bat lyssavirus) has been associated with two human fatalities. Effects on embryonic development are unknown.
(More? Abnormal Development - Virus)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original M

macrosomia

Term used to describe a newborn with an excessive birth weight. The definition is either a birth weight of 4000 to 4500 g (8 lb 13 oz to 9 lb 15 oz) or greater than 90% for gestational age after correcting for neonatal sex and ethnicity.
(More? Human Fetal Weight | Maternal Diabetes)

magnetoencephalographic

(MEG) A brain imaging system that measures electromagnetic changes in regions of the brain that correspond to activity.

major urinary proteins

(MUPs) Proteins which carry volatile substances, including pheromones, and protect them during their internal passage (liver to kidneys into urine).
(More? Mouse Development- Estrous Cycle)

male factor

Any cause of infertility due to deficiencies in sperm quantity, function, or motility (ability to move) that make it difficult for a sperm to fertilize an egg under normal conditions.
(More? Week 1 Notes)

manchette

A transient microtubule structure formed in spermatids involved in the process of assembly of the mammalian sperm tail and mechanical shaping and condensation of the sperm nucleus.
(More? Spermatogenesis | Fertilization)

mandible

Term used to describe the lower jaw of the face, which forms from the lower part pharyngeal arch 1, the mandibular process. The smaller upper part of pharyngeal arch 1 forms the two maxillary processes, which form the upper jaw.
(More? Face Development | Face Abnormalities | Head Development)

mandibular process

In head and face development, lower part and majority of pharyngeal arch 1 which forms the lower jaw (mandible) of the face Smaller upper part of pharyngeal arch 1 are the maxillary processes.
(More? Face Development | Face Abnormalities | Head Development)

mammary gland

A specialised modified secretory gland producing milk in female mammals for neonatal nutrition. Note that milk production and neonatal nutrition through milk, define us as mammals.
(More? Integumentary Development - Mammary Glands)

massive chronic intervillositis

(chronic intervillositis, chronic histiocytic intervillositis) Rare placental abnormality and pathology defined by inflammatory placental lesions, mainly in the intervillous space (IVS), with a maternal infiltrate of mononuclear cells (monocytes, lymphocytes, histiocytes) and intervillous fibrinoid deposition.
(More? Placenta Abnormalities)

maternal

Term relating to the mother and used genetically, biologically and legally. The term paternal relates to the father.

maternal passive immunity

(maternal passive immunity) Term used to describe the transfer of maternal antibodies to the fetus (through the placenta) and the neonate (through milk).
(More? Placenta | Normal Development - Milk)

maternal mortality rate

Statistical term defined as the number of maternal deaths per 100,000 live births.
(More? Statistics- Australian Maternal Statistics | Statistics - World Death)

Math1

(Mouse homolog of ATH1, also called Atoh1) Basic helix-loop-helix (bHLH) transcription factor both necessary and sufficient for hair cell development in the mammalian cochlea.
(More? Hearing Development | OMIM ATONAL)

matrix

Term used to describe the non-cellular material in which cells are embedded, as in the extracellular matrix. The term matrix is also used in cell biology to describe the space within mitochondria, enclosed by the two mitochondrial membranes.

MAVS

Mitochondrial AntiViral Signaling, induces interferon expression and therefore increased antiviral defenses.

maxillary process

In head and face development, upper part of pharyngeal arch 1 which forms as a pair of small lateral swellings which contributes the upper jaw and forms the palatal shelves. Larger lower part of pharyngeal arch 1 is the mandibular process. Associated abnormality is cleft palate/lip.
(More? Face Development | Face Abnormalities | Head Development)

Mayer- Rokitansky-Kuster-Hauser syndrome

(MRKH) Abnormality of development of the female genital tract: partial or complete absence (agenesis) of the uterus; absent or hypoplastic vagina; normal fallopian tubes, ovaries, normal external genitalia and normal female chromosome pattern (46, XX).

measles

(paramyxovirus) A single-stranded RNA virus which is highly contagious. Before measles vaccination (USA 1963) more than 90% of children had an infection before puberty and in developing countries it is still a common and often fatal childhood disease. Pregnancy effects of measles results in a higher risk of premature labor, spontaneous abortion, low-birth-weight, and possibly rare cases of birth defects with no definable pattern of malformation.
(More? Viral Infection)

meatal plate

An ectodermal plug that temporarily blocks the external auditory meatus of the ear.
(More? Senses Notes)

meatus

(Latin, meatus = a channel or way) An anatomical description of an opening or passageway (external auditory meatus, female urethral meatus).
(More? Senses - Hearing)

meatoplasty

A surgical technique allowing reconstructive surgery of the external ear canal, often used to treat external meatus stenosis
(More? Ear Abnormalities)

Meckel's cartilage

A temporary cartilage located in the first pharyngeal arch (mandibular component) that forms the template for formation of the mandible and middle ear bones. Named after Johann Friedrich Meckel, the Younger a German anatomist (1781 - 1833).
(More? Head Notes | Who Named it? Johann Friedrich Meckel | PalaeosThe Gill Arches: Meckel's Cartilage )

meconium

The gastrointestinal contents that accumulate in the intestines during the fetal period. This material is a mixture of liver bile and glandular secretions, amniotic fluid, and cellular debris. Meconium is also used to describe the first postnatal rectal discharge from the neonate. Fetal stress in the third trimester or at parturition can lead to premature meconium discharge, into the amniotic fluid and ingestion by the fetus (meconium aspiration syndrome) and damage to respiratory function. Damage to placental vessels [#meconium_myonecrosis meconium myonecrosis] may also occur.
(More? Birth | Gastrointestinal Tract Notes | Respiratory Notes)

meconium aspiration syndrome

(MAS) Fetal stress in the third trimester, prior to/at/ or during parturition can lead to premature meconium discharge into the amniotic fluid and sunsequent ingestion by the fetus and damage to respiratory function. Damage to placental vessels meconium myonecrosis may also occur.
(More? Birth | Gastrointestinal Tract Notes | Respiratory Notes)

meconium myonecrosis

Placental pathology resulting from prolonged meconium exposure which is toxic for myocytes of placental vessels (umbilical cord or chorionic plate).
(More? Placental Notes)

meconium peritonitis

(MP) A sterile chemical peritonitis resulting from small bowel perforation in utero. Often detected by ultrasound and can result in a mortality rate as high as 60%.

meconium plug syndrome

(functional immaturity of the colon) Term used to describe a transient disorder of the newborn colon, which is characterized by delayed passage of meconium (more than 24 to 48 h), intestinal dilatation and yellow/green vomiting. More common in premature infants and can be determined by radiological dye study.
(More? GIT Abnormalities | Gastrointestinal Tract Notes | Birth | PMID: 18485962 | U Mich - Meconium Plug Syndrome)

medial

(Latin, medialis = middle) Anatomically towards the midline of the body or structure. The opposite term is lateral.

medial epithelial seam

(MES) Embryonic structure formed by the fusion of the two palatal shelves, forming a two-layered medial edge epithelial seam, which is then lost with palate development.
(More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)

mediastinum testis

(Latin, medialis = middle) A single conical mass of connective tissue within the testis (male gonad) which extends from the tunica albuginea (cortical thick capsule surrounding the testis) into the seminiferous tubule region (medullary). Embedded within this connective tissue are the rete testis component of the duct conduction system for spermatazoa (Spermatozoa Duct Pathway: seminiferous tubule ‚ straight tubule ‚ rete testis ‚ ductuli efferentes ‚ ductus epididymidis ‚ ductus deferens)
(More? Spermatogenesis)

median eminence

(Latin, medialis = middle) A midline pouch or recess in the floor of the third ventricle and an extension of the hypothalamus together with the neural stalk forms the infundibular stem, which in turn together with the posterior lobe forms the pituitary neurohypophysis.
(More? Endocrine - Hypothalamus | Endocrine - Pituitary )

medullary

(Latin, medialis = in the middle) Term relating to the medulla; pith, marrow, inner portion of an organ. Usually combined with cortex (cortical) meaning the outer layer.

medulloblast

An undifferentiated cell of the embryonic neural tube that can develop into either a neuroblast or spongioblast similar to a neural stem cell.

medulloblastoma

The most common malignant brain tumor in children (leading causes of cancer-related death in children under 9 years of age) and is thought to result from the transformation of granule cell precursors in the developing cerebellum. Approximately 25% of medulloblastoma cases have mutations in components of the Sonic hedgehog - Patched signaling pathway.
(More? Neural System - Abnormal Development | Molecular Development - Sonic hedgehog)

megalin

A transmembrane protein acts as an endocytic receptor on the apical surface of polarised epithelial cells. It requires interaction with another protein, cubulin, for the endocytosis of ligands. In development, it has been shown that sonic hedgehog can also bind megalin and this interaction now requires further research.
(More? Molecular Development - Sonic hedgehog | NCBI Bookshelf - Megalin)

megacolon

(intestinal aganglionosis, aganglionic colon, Hirschsprung's Disease) Gastrointestinal tract abnormality due to a lack of enteric nervous system (neural ganglia) in the intestinal tract responsible for gastric motility (peristalsis). In general, its severity is dependent upon the amount of the GIT that lacks intrinsic ganglia, due to an earlier developmental lack of neural crest migration into those segments.
(More? Gastrointestinal Tract Abnormalities | Neural Crest Abnormalities)

meiosis

The cell division that occurs only in production of germ cells where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. Note all other non-germ cells divide by mitosis.
(More? Week 1 Notes)

meiotic sex chromosome inactivation

(MSCI) The process of transcriptional silencing of the X and Y chromosomes that occurs only during male meiotic spermatogenesis. This is a specialised form of [#MSUC meiotic silencing of unsynapsed chromatin]. This specific silencing has also be called the second form of X chromosome inactivation, the first form occurs in all female embryo cells.
(More? Meiotic sex chromosome inactivation. Turner JM. Development. 2007 May;134(10):1823-31.)

meiotic silencing of unsynapsed chromatin

(MSUC) An aneuploidy protective mechanism for subsequent generations, during meiosis where chromosomes are silenced that fail to pair with their homologous partners.

melanocyte

A pigmented cell located in the skin, neural crest in origin. This cell type proliferates in the cancer melanoma.
(More? Neural Crest Notes)

melatonin

An endocrine hormone secretd from the pineal gland involved with the diurnal cycle, melatoinin levels are high in dark, low in daylight.
(More? Endocrine Notes | Pineal Gland)

membrana granulosa

The granulosa cells that line the developing follicles of the ovary. These cells proliferate to form the stratum granulosa and other granulosa cells are given specific names based upon their position within the follicle. In the antral follicle, membrana granulosa sits on the follicular basal lamina and lines the antrum as a stratified epithelium. The cumulus oophorus is a column of granulosa cells that attaches the oocyte to the follicle wall. The corona radiata are the granulosa cells that directly surround the oocyte, and are released along with it at ovulation. Following ovulation the corona radiata provide physical protection to the oocyte and granulosa cells within the ovulating follicle contribute to corpus luteum.
(More? Week 1 - Oogenesis)

meningoceles

The herniation of the meninges through a skull or spinal defect, formed from a neural tube defect. Spinal cord meningoceles have three classifications: simple meningocele, lateral meningocele and anterior sacral meningocele.

meningococcal disease

(meningitis) Disease can be a viral or bacterial infection of cerebrospinal fluid of the spinal cord and brain. Treatment and outcomes differ for either viral (less severe, resolves without specific treatment) or bacterial (severe, may result in brain damage, hearing loss, or learning disability) infections.
(More? Abnormal Development - bacteria | Postnatal Development | CDC - meningococcal disease)

menopause

(Greek, mene = moon, men = month, pause = end or cessation) The decrease in ovarian production of estrogen and progesterone leading to cessation of menstrual cycles, decrease in fertility, and end of female reproductive life. Usually occurs in the mid-40's, the term was first used by the French physician, de Gardanne in 1812.
(More? Human Menstrual Cycle | Medline Plus - Menopause)

menorrhagia

Term used to describe heavy menstrual bleeding, is common in women of reproductive age (WHO data, affects 1011 out of 5322 women).
(More? Human Menstrual Cycle)

menstrual age

The gestation time calculated from the first day of the last menstrual period (LMP) prior to fertilization. In humans, this differs from embryonic age by approximately two weeks.
(More? Week 1 Notes)

menstrual cycle

The human reproductive cycle, an endocrine regulated change in female anatomy and physiology that occur over 28 days (4 weeks, a lunar month) during reproductive life (between puberty and menopause). This cycle ceases during pregnancy and differs from other non-primate vertebrates (eg rats, mice, horses, pig) females that have a reproductive cycle called the estrous cycle (oestrous, British spelling).
(More? Human Menstrual Cycle | Estrous Cycle)

merle

The pattern of coloring observed in the coat of the domestic dog and is characterized by patches of diluted pigment. Dogs inherit trait in an autosomal, incompletely dominant fashion and heterozygous or homozygous for the merle locus exhibit a wide range of auditory and ophthalmologic abnormalities, similar to those in human Waardenburg syndrome.
(More? Animal Embryos | PNAS Article 2006)

meromelia

(Greek, melia = limb) A limb abnormality with the partial absence of a limb, as described in the original classical classification of limb deficiencies.
(More? Limb Abnormalities - Classification)

mesangial cell

(glomerular mesangial cell) A kidney epithelial cell type located in the nephron (functional kidney unit) surrounding glomerular capillaries (blood vessels). Mesodermal in origin, there are mesangial cells within (intraglomerular) and outside (extraglomerular) the glomerulus. Have several functions including: contractile activity (smooth muscle-like) controlling blood flow and basement membrane surface area (glomerular filtration rate), structural support, phagocytosis (remove basal lamina components and immunoglobulins).
(More? Nephron Notes)

mesencephalon

(midbrain, mes = mid, encephalon = brain) The embryonic neural tube region that will form midbrain structures of the tectum and tegmentum in the adult brain. The mesencephalon is the middle of the 5 secondary brain vesicles formed from the mesencephalon of the primary brain vesicle (there are 3 primary brain vesicles). The mesencephalon lumen (cavity of the neural tube) will form the midbrain aqueduct.
(More? 2009 Lecture - Early Neural Development | Neural Notes | Ventricular System)

mesenchyme

Term used to describe the cellular organisation of undifferentiated embryonic connective tissue. Mesenchymal tissue is mainly derived from mesoderm and neural crest, which will form most of the adult connective tissues. This connective tissue organization contrasts with the other main form of cellular organization, epithelial tissue.
(More? Musculoskeletal Notes)

mesenchymal stem cell

The cells derived from various connective tissues that form a population of stem cells with potential to differentiate for repair and replacement of connective and other tissues. Can be found mainly in bone marrow, but also in other places (dermis, lung and heart atria). The bone marrow mesenchymal stem cell (or bone marrow stromal cell) differs from the hematopoietic stem cell (which forms blood cells) and can form bone, cartilage and adipose tissue.

mesentery

The tissue fold attaching gastrointestinal tract to posterior abdominal wall in which blood vessels, lymph and nerves run. Developmentally derived from lateral plate mesoderm forming splanchnic mesoderm which then forms the posterior mesogastrium.
(More? mesogastrium | GIT Notes)

mesethmoid cartilage

The ventral component of the nasal capsule. In the chicken embryo, it is induced by sonic hedgehog (Shh) expression from endoderm (endoderm zone I).
(More? Face Notes)

mesoderm

The middle layer of the 3 germ cell layers of the embryo. Mesoderm outside the embryo and covering the amnion, yolk and chorion sacs is extraembryonic mesoderm.
(More? Musculoskeletal Notes | Week 3 Notes)

mesodiencephalic dopaminergic neurons

(mdDA) Central nervous system neurons that control voluntary movement and reward based behaviour, which are lost in Parkinson's disease. Their embryonic origin progenitor cells are located in the caudal diencephalon and midbrain floorplate region.

mesogastrium

The developmental term for the splanchnic mesoderm forming early mesenteries (dorsal and ventral) that support the developing gastrointestinal tract. The majority of the ventral mesentery is developmentally lost at the level of the midgut and the dorsal mesentery remains in the adult, through which blood vessels, nerves and lymph connects to the gastrointestinal wall. Note that specific visceral organs also develop within each mesogastrium.
(More? GIT Notes)

mesonephros

The second temporary stage of kidney development (pro-, meso-, meta-). The intermediate mesonephros develops and disappears with the exception of its duct, the ===mesonephric duct===, which will form the male reproductive duct system. In males, the mesonephric tubules go on to form the ducts of the testis. In females, these degenerate. A few mesonephric tubules remain as efferent ductules in the male and vestigial remnants in the female.
(More? Urogenital Notes)

mesonephric duct

(= Wollfian duct) An early developing urogenital paired duct system that initially runs the length of the embryo, that will differentiate and form the male reproductive duct system (ductus deferens). In females, this duct degenerates occasionally some remnants may remain associated in broad ligament.
(More? Genital Notes)

mesorchium

A peritoneal fold attaching testes to the mesonephros during development.
(More? Genital Notes)

mesovarium

The mesentry of the ovary formed from a fold of the broad ligament that attaches the ovary.
(More? Week 1 Notes)

messenger RNA

(mRNA) The form of RNA that is translated into a protein amino acid sequence by the ribosome.

metanephros

The adult kidney, third stage of mammalian kidney (pro-, meso-, meta-) development within the intermediate mesoderm.
(More? Urogenital Notes)

metanephric cap

In kidney development, the intermediate mesoderm (metanephric mesenchyme) which surrounds the ureteric bud and will develop into nephrons.
(More? Urogenital Notes)

metanephric mesenchyme

Metanephric mesenchyme caudal part of intermediate mesoderm that will develop into nephrons within the kidney. The intermediate mesoderm forms as an unsegmented strip running rostro-caudally between the somite and lateral plate mesoderm. The very caudal (tail) end of this mesoderm strip where the uteric bud forms is the metanephric mesenchyme, which induces the formation of, and surrounds the end of, the ureteric bud.
(More? Urogenital Notes)

metaphase

One of the 5 mitosis phases (prophase, prometaphase, metaphase, anaphase, and telophase). Originally based on light microscopy of living cells and electron microscopy of fixed and stained cells. At metaphase kinetochore microtubules align chromosomes in one midpoint plane. Metaphase ends when sister kinetochores separate.
(More? Week 1 Notes | Week 1 Mitosis)

metencephalon

(encephalon = brain) The embryonic neural tube region that will form hindbrain structures of the pons and cerebellum in the adult brain. The metencephalon is the fourth of the 5 secondary brain vesicles formed from the rhombencephalon of the primary brain vesicle (there are 3 primary brain vesicles). The metencephalon lumen (cavity of the neural tube) will form the fourth ventricle.
(More? Neural Notes | Ventricular System)

methionine aminopeptidase

(MetAPs) An enzyme family of cytosolic metalloproteases which are responsible for cleavage from nascent proteins (newly translated) of the initial methionine from the N termini. Eukaryotes express two forms of MetAPs (types 1 and 2), with type 2 required for normal vascular development, deletion in mouse causes embryonic death at the midsomite stage.
(More? Cardiovascular Notes)

methyldopa

(alpha methyldopa) A central alpha agonist used to lower blood pressure. Used as an antihypertensive drug to lower blood pressure in pre-eclampsia, acting by either a direct or indirect central vasodilatory mechanism. A recent study suggests this drug may have a direct effect on placenta and/or endothelial cell function in pre-eclampsia patients, altering angiogenic proteins. Drug commercial brandname (USA) "Aldomet", also available in combination with other drugs: methyldopa and chlorothiazide "Aldochlor", methyldopa and hydrochlorothiazide "Aldoril".
(More? Placenta Abnormalities - Pre-eclampsia | Medline Plus - Methyldopa | Effect of antihypertensive therapy with alpha methyldopa on levels of angiogenic factors in pregnancies with hypertensive disorders. Khalil A, Muttukrishna S, Harrington K, Jauniaux E. PLoS ONE. 2008 Jul 23;3(7):e2766. PMID: 18648513)

metopic suture

A skull fibrous joint, cranial suture between adjacent developing bones of the skull. This suture begins at nose and runs superiorly to meet sagittal suture and fuses in early childhood before all other cranial sutures. Premature fusion (synostosis) of metopic suture causes Trigoncephaly (wedge skull).
(More? Skull Notes | Head Notes)

methylmercury

(organic mercury) Toxic form, at high concentrations, of mercury found in the environment (air, water, soil, plants and animals) and is different from elemental mercury (thermometers, dental amalgams). Industrial mercury can enter water systems, which is then converted into methylmercury and can contaminate exposed fish or shellfish, entering the human food chain.
(More? Abnormal Development - Heavy Metals)

MiRNA

Acronynm for [#MicroRNA MicroRNA] a small noncoding ribonucleotide-based (RNA) regulators of gene expression. They have diverse functions including regulation of cellular differentiation, proliferation and apoptosis.

microcephaly

An abnormally small skull cranium marked by premature fusion of the skull sutures and also under-developed brain.

microchimerism

(Mc) Term used to describe when a usually small population of cells or DNA is harbored by one individual that derive from a genetically distinct individual. May occur in pregnancy when cells exchange beween fetus and mother, mother and fetus or in twinning.

microphthalmia

(microphthalmos) The abnormality of development of a small eye within the orbit. This condition has been reported in up to 11% of blind children.

microphthalmia-associated transcription factor

(MITF) A protein, basic helix loop helix (bHLH) zipper transcription factor, key to regulating melanocyte development. Also functions as an oncogene in malignant melanoma.
(More? OMIM - MITF | Lecture - Neural Crest Development | Lecture - Integumentary System | Neural Crest Notes)

MicroRNA

(miRNA) a small noncoding ribonucleotide-based (RNA) regulators of gene expression. These recently discovered small RNA molecules (18-24 nucleotides) negatively regulate target mRNAs and appear to have a role in many developmental processes as well as in the adult. (See also "Dicer") There is also another class of small RNAs involved in gene expression present in cells, small interfering RNAs (siRNAs), generated from double-stranded RNA (dsRNA) precursors.

microtia

The condition of an abnormally small external ear.
(More? Abnormal Ear | Microtia)

midbrain

(mesencephalon) An early subdivision of the brain development at the stage when there are three primary vesicles or expansions of the early neural tube (forebrain, midbrain, hindbrain) also present at the later five secondary vesicle stage. Term is used in the adult brain to describe brainstem components formed including: tectum, tegmentum, the ventricular mesocoelia, cerebral peduncles, and additional nuclei and fasciculi.
(More? Neural Notes)

midbrain flexure

(pontine flexure) pontine flexure The middle curvature that forms in the early rapidly growing neural tube.
(More? Neural Notes)

midgut

The middle of the three part/division (foregut - midgut - hindgut) of the early forming gastrointestinal tract. The midgut is initially connected on the ventral embryo surface to the external yolk sac by a yolk stalk, a narrow tubular connection. The midgut forms all the tract from beneath the stomach (duodenum, small intestine and large intestine) to the distral transverse colon. The midgut develops as an external loop "herniated" ventrally, until early fetal growth of the body wall recaptures this external loop, which also undergoes a rotation about the superior mesenteric artery to establish the adult anatomical position.
(More? Gastrointestinal Tract - Intestine | Gastrointestinal Tract Notes)

mifepristone

(RU 486) The commercial name for a progesterone receptor antagonist similar in structure to the natural hormone progesterone, which is used medically as a birth control drug.
(More? Birth Control)

miscarriage

The loss of embryo or fetus by spontaneous abortion.

misoprostol

A drug used in medical management of first trimester miscarriage, in some countries often in combination with [#mifepristone mifepristone]. Drug is a potential teratogen, used in non-pregnant treatment to prevent ulcers in people taking some arthritis or pain medicines.
(More? Medline Plus - misoprostol)

missed abortion

(blighted ovum) Term previously used to describe early fetal loss, embryo loss in first trimester.

mitosis

The normal division of all cells, except germ cells, where chromosome number is maintained. Note germ cell division (egg, sperm) is reductive meiotic division.
(More? Week 1 Notes)

MMR

Acronym for Measles-Mumps-Rubella vaccine.
(More? Normal Development - Immunization | Abnormal Development - Rubella Virus)

modulo

Drosophila transcription factor which binds to the promoter of spermatid-differentiation gene Sdic and integrate meiosis and spermatid differentiation in the male germ line. (homologue of nucleolin)
(More? PNAS paper | OMIM nucleolin)

monozygotic twin

Twins (identical) produced from a single fertilization event (one fertilised egg and a single spermatazoa, form a single zygote), these twins therefore share the same genetic makeup. Occurs in approximately 3-5 per 1000 pregnancies, more commonly with aged mothers. Late monozygotic twins can result in conjoined twins or both a shared placenta and a shared amniotic sac (monochorionic monoamniotic twins). Note dizygotic twins (fraternal) arise from separate fertilizations of different eggs.
(More? Twinning | Week 1 Twinning)

morbidity

(Latin, morbidus = "sick" or "unhealthy") Clinical term refers to a diseased state, disability, or poor health due to any cause.

morphogenesis

Term used to describe the process of development involving a change in form (shape) and size or either cells or tissues.

morphogenetic field

Term used to describe a group of cells with a similar developmental fate, forming a specific structure or organ (forelimb, eye, heart).

morula

(Latin, morula = mulberry) An early stage in post-fertilization development when cells have rapidly divided to produce a solid mass of cells (12-15 cells) with a "mulberry" appearance. This stage is followed by formation of a cavity in this cellular mass (blastocyst stage). In humans, morula stage of development occurs during the first week following fertilization.
(More? Week 1 Notes | Week 1 Early Cell Division)

MIS

Acronym for Mullerian Inhibiting Substance, a hormone that regulates genital development.

MSC

Acronym for mesenchymal stem cell, a connective tissue stem cell.

MSH

Acronym for muscle specific homeobox (which is not muscle specific), a homeobox gene involved in pattern formation in several systems in development.

MSS

Acronym for Maternal Serum Screening, used to detect potential genetic abnormalities in both mother and embryo.
(More? Abnormal Development - Genetic)

Mullerian Duct

(paramesonephric duct) An embryonic paired duct system that will form the epithelial lining of female reproductive organs: utererine tube, uterus, upper vaginal canal. This duct system degenerate in male gonadal development. Named after Johannes Peter Muller (1801-1858) a German scientist.
(More? Uterus Development | Genital System - Female | X chromosome | Human Menstrual Cycle | Genital Notes)

Johannes Peter Mullerian

Johannes Peter Muller (1801 - 1858) in 1830 was the first to describe the duct named after him, the "Mullerian duct" also called the paramesonephric duct.
(More? Uterus Development | Genital System - Female | X chromosome | Human Menstrual Cycle | Genital Notes)

Mullerian Inhibiting Substance

(MIS, Anti-Mullerian Hormone, AMH, Mullerian inhibiting hormone, MIH). A sertoli cell secreted glycoprotein (transforming growth factor-beta, TGF-beta superfamily) that regulates gonadal and genital tract development. The main role is to inhibit paramesonephric (Mullerian) duct development in males. Postnatally, after puberty it is also expressed in females by ovarian granulosa cells and has a role in follicle development.
(More? Male | OMIM - AMH)

multifetal pregnancy reduction

A procedure used to decrease the number of fetuses a woman carries and improve the chances that the remaining fetuses will survive and develop into healthy infants. Multifetal reductions that occur naturally are referred to as spontaneous multifetal reductions.

multiple birth

A pregnancy that results in the birth of more than one infant.
(More? Twinning Notes)

mutagen

A chemical or agent that can cause permanent damage to the deoxyribonucleic acid (DNA) in a cell. DNA damage in the human egg or sperm may lead to reduced fertility, spontaneous abortion (miscarriage), birth defects and heritable diseases.

muscle

Term used to describe the tissue that has contractile activity, also used to describe the functional cells that contract. There are three main types of muscle: smooth, cardiac and skeletal. Muscle is mesodermal in origin, each muscle type coming from a different mesoderm region.
(More? Musculoskeletal Notes)

Mycoplasma genitalium

M. genitalium A parasitic bacterium that can populate the epithelial layer of human uterine (Fallopian) tubes and lead to cilia damage and therefore contribute to tubal factor infertility. A recent study has shown that M. genitalium can also bind to human spermatozoa, could be carried by motile sperm, and contribute to this process of female genital disease and infertility.
(More? Week 1 - Abnormalities)

myelomeningocele

(spina bifida) A neural tube defect, a form of spina bifida (developmental abnormalities leading to failure of closure of the spinal column). Can be of two forms: spina bifida occulta (spinal column fails to close, spinal cord and meninges remain in place and defect is covered by skin) meningoceles (tissue covering the spinal cord sticks out of the spinal defect but the spinal cord remains in place)
(More? Neural Abnormalities)

myelencephalon

(Greek, enkephalon = brain) The embryonic neural tube region that will form hindbrain structures of the medulla oblongata in the adult brain. The myelencephalon is the last vesicle before the spinal cord the fifth of the 5 secondary brain vesicles formed from the rhombencephalon of the primary brain vesicle (there are 3 primary brain vesicles). The myelencephalon lumen (cavity of the neural tube) will form the lower part of the fourth ventricle.
(More? Neural Notes | Ventricular System)

myoblast

The undifferentiated mononucleated muscle cells that will fuse together to form a multinucleated myotube, then mature into a muscle fibre.
(More? Musculoskeletal Notes)

myocardin

A protein that acts as a transcriptional co-activator of serum response factor (Srf), which is a regulator of both smooth and cardiac muscle gene expression.
(More? Heart Molecular | Creemers EE, Sutherland LB, McAnally J, Richardson JA, Olson EN. Myocardin is a direct transcriptional target of Mef2, Tead and Foxo proteins during cardiovascular development. Development. 2006 Oct 4)

MyoD

Myoblast determining factor, a transcription factor involved in the determination of muscle cells in the somite. A basic helix-loop-helix factor which binds DNA.
(More? Musculoskeletal Notes | Molecular Notes)

myogenesis

The process of muscle cell development or formation. In skeletal muscle the cellular sequence is: myoblast, myotube and myofibre.
(More? Musculoskeletal Notes | Molecular Notes)

myonecrosis

The term used to describe pathological death of myocytes. Can occur during development in placental vessels (umbilical cord or chorionic plate) following prolonged exposure to meconium (meconium myonecrosis).
(More? Placental Notes

myotendinous junction

(MTJ) The specialiazed junction between a skeletal muscle and the tendon which transmit the force of the muscle contraction to the bone of the skeleton. Their role is to transmit the force of the muscle contraction. The histology of tendons is that of a dense regular connective tissue high in collagen type I. During development the MTJ has a unique microenvironment.
(More? Ligament Tendon Notes | Ligament Tendon Notes)

myotome

The portion of the dermamyotome that generates skeletal muscle. Has 2 components epaxial (dorsal muscles) hypaxial (ventral muscles)
(More? Musculoskeletal Notes)

myotube

The initial multinucleated cell formed by fusion of myoblasts during skeletal muscle development.
(More? Musculoskeletal Notes)

myxomatous

The term (histology/pathology) used to describe a connective tissue embedded in mucus, for example Wharton's jelly of the placental cord.
(More? Placenta Histology)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

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Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original N

nanog

Homeodomain-containing transcription factor involved in maintaining embryonic stem (ES) cell self-renewal. Name is derived from Celtic "Tir Na Nog" a mythologic Celtic land of the ever young.
(More? OMIM NANOG | Molecular Factors- Nanog)

nail-patella syndrome

(NPS) rare (1/50,000) Autosomal dominant disorder characterized by hypoplastic or absent patellae, dystrophic nails, dysplasia of the elbows and iliac horns. Potentially due to mutations in LMX1B, a LIM-homeodomain transcription protein.
(More? OMIM nail-patella syndrome | LMX1B)

necrosis

(Greek, nekros = corpse) Pathological cell death from extrinsic injury. Cell lyses releasing cytoplasmic contents which may also have a role in initiating an inflammatory response.
(See also apoptosis)

Necrotizing Enterocolitis

(Greek, nekros = corpse) Gastrointestinal tract pathology occurring postnatally in mainly in premature and low birth weight infants (1 in 2,000 - 4,000 births). The underdeveloped gastointestinal tract appears to be susceptible to bacteria, normally found within the tract,to spread widely to other regions where they damage the tract wall and may enter the bloodstream.Pathological cell death from extrinsic injury. Cell lyses releasing cytoplasmic contents which may also have a role in initiating an inflammatory response.
(More? Gastrointestinal Tract Abnormalities | Medline Plus - Necrotizing Enterocolitis)

Neisseria gonorrhoeae

A gram-negative bacteria which causes the disease Gonorrhea, which is a sexually transmitted disease (STD).
(More? Abnormal Development - Bacterial)

nebenkern

(German, nebenkern = subsidiary nucleus) A mitochondrial aggregate formed during developemnt of the Drosophila spermatazoa. The individual mitochondria fuse into two giant mitochondria arranged in a sphere of many layers of "onion-like" wrapped mitochondrial membranes. This process appears to only occur in some insect spermatogenesis.
(More? Drosophila Development | Meiosis | Spermatogenesis)

neonatal

Term used in relation to the newborn infant and up to four weeks old.

neoplastic rest

In kidney development, a neoplastic rest can develop under either genetic or epigenetic influence from a hyperplastic rest, originating from an embryonic blastema cell. Normally the majority of nephrogenic rests either regress or become dormant.
(More? Wilm's tumour | nephrogenic rest | Urogenital Abnormalities | Urogenital Notes)

nephrin

Structural protein of the kidney nephron, forming a major component of the glomerular slit diaphragm. Also acts late in the process of podocyte differentiation as a signaling molecule influencing foot process formation and the maintenance of podocyte integrity.
(More? Lecture - Kidney Development | Urogenital Notes)

nephroblastoma

A childhood kidney cancer see Wilm's tumour
(More? Lecture - Kidney Development | Urogenital Notes)

nephrogenic rest

A kidney term used to describe the embryonic blastema cells which persist and under either genetic or epigenetic can change to become a neoplastic rest. These neoplastic rests can develop postnatally as a benign form (adenomatous rest) or a malignant Wilm's tumour form. The rests are further characterised by the time of generation leading to different anatomical kidney locations: early intralobar nephrogenic rests (within the renal lobe) and late pelilobar nephrogenic rests (periphery of the renal lobe).
(More? Wilm's tumour | Urogenital Abnormalities | Urogenital Notes)

nephron

(Greek, nephros = kidney) The functional unit of the kidney.
(More? Lecture - Kidney Development | Urogenital Notes)

nephros

(Greek, nephros = kidney) Term used to describe features associated with the kidney. (pronephros, mesonephros, metanephros, nephric, nephron, nephroblastoma)
(More? Lecture - Kidney Development | Urogenital Notes)

nestorone

A synthetic progesterone potentially used in postmenopausal women (with an intact uterus in combination with estrogen as hormone-replacement therapy (HRT). (Other Progestins: levonorgestrel, 3-keto-desogestrel, dienogest, drospirenone, Nestorone and nomegestrol acetate) Trimegestone and Nestorone are currently the most potent fourth-generation progestins with no androgenic or estrogenic actions.
(More? Human Menstrual Cycle)

neuralation

The general term used to describe the early formation of the nervous system. It is often used to describe the early events of differentiation of the central ectoderm region to form the neural plate, then neural groove, then neural tube. The nervous system includes the central nervous system (brain and spinal cord) from the neural tube and the peripheral nervous system (peripheral sensory and sympathetic ganglia) from neural crest. In humans, early neuralation begins in week 3 and continues through week 4.
(More? Neural Notes | Neural Crest Notes | Development Week by Week

neural crest

A cell region at edge of neural plate, then atop the neural folds, that remains outside and initially dorsal to the neural tube when it forms. These paired dorsal lateral streaks of cells migrate throughout the embryo and can differentiate into many different cell types (= pluripotential). Those that remain on the dorsal neural tube form the sensory spinal ganglia (DRG), those that migrate ventrally form the sympatheitic ganglia. Neural crest cells also migrate into the somites and regions throught the entire embryo.
(More? Neural Crest Notes)

neural folds

The central region of the trilaminar embryo ectoderm called the neural plate region folds dorsally, generating two neural folds, which later fuse to form the neural tube. The mid-line depression between the two folds is described as the neural groove. In humans at approximately day 18-19 post-fertilization to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
(More? Neural Notes)

neural groove

The second stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate. This epithelium will fold dorsally, beginning in humans at approximately day 18-19 post-fertilization to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
(More? Neural Notes)

neural plate

The first stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate. This epithelium will fold dorsally to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
(More? Neural Notes)

neural stem cell

(NSC) A stem cell within the central nervous system (CNS) that can proliferate indefinitely and give rise to either neurons, astrocytes, and oligodendrocytes.
(More? Neural Stem Cell Notes | Neural Notes | Stem Cell Notes)

neural stem cell niche

Locations within the nervous system that multipotent stem cells reside and participate in specialized microenvironments that support cell self-renewal and differentiation.
(More? Neural Stem Cell Notes | Neural Notes | Stem Cell Notes)

neural tube

The third stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate . This epithelium will fold dorsally to form the neural groove, which then fuses to form initially a hollow tube open at either end (neuropores). The neural tube forms the central nervous system (brain and spinal cord).
Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
(More? Neural Notes)

neuroblastoma

A tumour derived from neural crest cells.
(More? Neural Crest - Abnormalities)

neuroenteric canal

The canal or opening existing early in trilaminar embryo development that provides transient communication between the amnion and the yolk sac. Canal forms as part of axial process development, the precursor to the notochord.
(More? Neural Notes)

neurogenesis

The process of formation of the neural system. Early neurogenesis begins with segregation of the neural plate from the ectoderm of the trilaminar embryo by folding to form initially the neural groove, which then fuses to form the neural tube (the central nervous system progenitor, brain and spinal cord) and associated neural crest. Later neurogenesis in the central nervous system is the proliferation of ventricular neural stem cells, differentiation, migration and lamination of the developing neural system.
Early developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord).
(More? Neural Notes)

neurogenin-3

(NEUROG3) Gene expressed in endocrine progenitor cells (including pancrea islet cells) and required for endocrine cell development in pancreas and intestine. Mutation in this gene depletes intestinal enteroendocrine cells resulting in malabsorptive diarrhea.
(More? Endocrine Notes | Endocrine Development - Pancreas)

neuron

(neurone) The cell forming the unit basis of the nervous system (both central and peripheral) capable of generating an action potential and releasing neurotransmitter. There are many different types of neuronal cells.
(More? Neural Notes)

neuropore

The initial two openings at either end of hollow neural tube called the cranial (rostral, anterior) and caudal (posterior). The cranial neuropore closes (day 25) approx. 2 days (human) before caudal. The developmental abnormality classed as Neural Tube Defects (NTDs) can be due to failure of these two neuropores to developmentally close and has been associated with low dietary folic acid.
(More? Neural Notes | Neural Abnormalities | Folic Acid and Neural Tube Defects)

neutrophil

(neutrophil granulocytes) A white blood cell granulocyte that has a central role in the inflammatory process, invade sites of infection in response to growth factors. Cell nucleus has a characteristic lobed appearance (3-5 lobes), the number of lobes increases with cell age. During the menstrual cycle, a cyclic change in neutrophil cell number in the endometrium is shown by vaginal smear.
(More? Cardiovascular System - Blood| Human Vaginal Smear Cells)

nicotine

A natural alkaloid ingredient in tobacco leaves, where it provides protection by acting as a botanical insecticide. There is an association between physical defects among newborns and maternal smoking tobacco during pregnancy.
(More? Abnormal Development Smoking | Smoking Workshop)

nicotinamide

The amide of vitamin B3 and is the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD+). Role in normal cellular function and metabolism and also recently identified as a protective agent against ethanol-induced cell death in the developing brain.
(More? Neural Notes | Fetal Alcohol Syndrome | [doi:10.1371/journal.pmed.0030101 PLoS - Medicine Article])

nidation

Term used to clinically describe implantation within the uterus.
(More? Week 2 Notes)

Nitabuch's layer

(fibrinoid layer) The layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
(More? Placenta)

Nogo

(Reticulon 4, RTN4, Neurite Growth Inhibitor 220) One of several myelin-associated proteins with inhibitory effects for neuronal neurite outgrowth. Nogo exists as 3 splice transcript variants (NOGO-A, NOGO-B and NOGO-C) which are differentially expressed in the developing central nervous system. Also associated with autoimmune demyelination, shown in models of multiple sclerosis (MS) such as experimental autoimmune encephalomyelitis (EAE).
(More? Nogo-A | Neural Notes | OMIM - Reticulon 4)

Nogo-A

A myelin-associated protein which can inhibit neurite outgrowth and prevent regeneration in the adult central nervous system. Secreted by oligodendrocytes in the central nervous system, but not by Schwann cells in the peripheral nervous system.
(More? Neural Notes | OMIM - Reticulon 4)

nosocomial

An infection acquired with medical treatment, generally associated with hospitals. Some forms of acquired infections may impact on fetal development either directly, by transmission to the fetus, or indirectly through maternal effects such as fever.
(More? Abnormal Development)

notch

A cell surface single-pass transmembrane receptor family (1-4) required for asymmetric cell division. Acts as a receptor for Jagged (1,2) and Delta-like (1,3,4) proteins and also interacts with a negative regulator (Numb) which is down-regulated by notch. Asymmetry of cell division allows generation of distinct progeny from a single cell division required in many developmental processes including neurogenesis.
(More? OMIM - NOTCH | OMIM - NUMB)

notochord

(axial mesoderm) The rod of cells lying in the midline of the trilaminar embryo mesoderm layer ventral to the neural tube. Thought to have at least 2 early roles in development and later roles in patterning surrounding tissues. 1. Mechanical, influencing the folding of the early embryo; 2. Morphogenic, secreting sonic hedgehog a protein which regulates the development of surrounding tissues (neural plate, somites, endoderm and other organs). In humans, the notochord forms in week 3 and is eventually lost during the formation of the vertebral column.
(More? Mesoderm Notes | Neural Notes | Molecular Development- Sonic Hedgehog)

Non-Hodgkin's lymphoma

(NHL) A type of cancer where the cause is unknowm and may develop in people with suppressed immune system. Treatment may cause premature ovarian failure. A recent study has shown CHOP therapy (cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, vincristine 1.4 mg/m2 (maximum 2 mg) and prednisone 100 mg/day for 5 days) does not affect the ovarian function or fertility.
(More? Medline Encyclopedia | PMID: 15817583)

NRT

An acronym for Nicotine Replacement Therapy, a method of replacing cigarette nicotine by either nicotine transdermal patches, nicotine gum, nicotine lozenges or nicotine inhalers.
(More? Abnormal Development Smoking | Smoking Workshop)

numb

A membrane-associated protein (also Numblike) involved in asymmetric cell division along with notch. Acts as a negative regulator of notch which can also down-regulate numb expression. Asymmetry of cell division allows generation of distinct progeny from a single cell division required in many developmental processes including neurogenesis.
(More? JCB - Notch and Numb | OMIM - NUMB | | OMIM - NUMBL | OMIM - NOTCH)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original O

OB-R

Leptin hormone receptor found in many different tissues. Receptor belongs to class I cytokine receptor family. These act through intracellular JAKs (Janus kinases) and STATs (signal transducers and activators of transcription) pathways.
(More? leptin)

obscurin

A large protein (820 kDa) located in the contractile sarcomere of skeletal and cardiac muscle. The protein has several different structural domains (68 immunoglobulin domains, 2 fibronectin 3 domains, 1 calcium/calmodulin binding domain, 1 RhoGEF domain).

obstetric fistula

Childbirth injury caused by several days of obstructed labour without prompt medical intervention. Blood supply is interrupted to surrounding tissues (bladder or rectum) leading to tissue death generating a hole or fistula. :(More? End Fistula Organisation)

Okihiro syndrome

abnormality of forearm with Duane syndrome of eye retraction. In humans, due to mutation in SALL4 gene on chromosome 20q13.13-q13.2.
(More? PMID: 12393809)

olfactory bulb

Region of the brain that olfactory sensory neurons connect by the olfactory nerve, (cranial nerve I). Anatomically these neuronal axons pass through the cribriform plate region of the skull.
(More? Senses Smell | Senses Notes)

olfactory

Term used to refer to the sense of smell and related structures (olfaction, olfactory epithelium, olfactory bulb, olfactory nerve CN I, olfactory epithelium).
(More? Senses Smell | Senses Notes)

olfactory epithelium

The specialised sensory epithelium that lines the nasal cavity associated with smell. Some cells within the adult epithelium remain as stem cells which can be isolated and purified.
(More? Senses Smell | Senses Notes | Stem Cell Notes)

olivocochlear

The brainstem cholinergic and GABAergic efferent system that innervates the sensory cells and the sensory neurons of the inner ear.

omphalocele

a congenital malformation with herniation of abdominal contents through the umbilicus, which can be covered by a membrane. Not to be confused with gastroschisis (para-umbilical hernia) or hypoplasia of abdominal muscles, skin-covered umbilical hernia.
(More? GIT Abnormalities)

omphalomesenteric artery

(vitelline artery) An embryonic artery carrying blood to the yolk sac from the embryo.
(More? Heart Notes)

omphalomesenteric duct

(vitelline duct, yolk stalk) A connection through the umbilicus between the yolk sac to the primitive gut that disappears at 8 to 9 weeks of gestation. Many developmental abnormalities are associated with failure of the vitelline duct to resorb, most commonly Meckel's diverticulum.
(More? GIT Abnormalities | GIT Movies | Pubmed omphalomesenteric duct malformations)

omphalomesenteric veins

(vitelline veins) Embryonic vessels providing the venous pole input into the heart from the yolk sac connected at the umbilicus.
(More? Heart Notes)

oocyte

(Greek, oo = egg, ovum) The term used to describe the haploid egg or ovum formed within the ovary (female gonad) and released to enter the uterine tube and be transported to the uterus. The mature oocyte is the cell released from the ovary during ovulation.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis)

oogenesis

(Greek, oo = egg + genesis = origin, creation, generation) process of diploid oogonia division and differentiation into an haploid oocyte (egg) within the ovary (female gonad). Mammalian meiosis will only be completed within the oocyte if fertilization occurs.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis)

oogonia

(Greek, oo = egg) diploid germ cells within the ovary (female gonad) which provide the primary oocytes for oocyte (egg) formation. In humans, all oogonia form primary oocytes within the ovary before birth.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis)

oophorus

(Greek, oo = egg + phorus = carrying, egg-bearing) cumulus oophorus, used to describe the granulosa cells within the follicle that tether or link the oocyte to the wall of the follicle.
(More? Week 1 - Oogenesis)

organogenic period

(embryonic period) In human development, this period of time corresponds to the first eight weeks (weeks 1 - 8) following fertilization when most organs are initially formed and also called the embryonic period. In other species this is also the initial period after fertilization, but will have a different overall time course.
(More? Embryonic Development)

oropharynx

The second portion of the pharynx (throat) that is posterior to the oral cavity. The other pharynx regions are the nasopharynx and laryngopharynx (hypopharynx).
(More? Respiratory Notes)

Orthoptera

(Greek, orthos = straight or rigid, ptera = wing) Order of insects including grasshoppers, locusts, katydids and crickets. Grasshopper neural development has been used as models for mechanisms of neural development.
(More? Other Embryos)

osteoarthritis

The most common form of arthritis that occurs after birth, caused by the accumulated wear of the cartilage in joints that disrupts the normal function of the joint, causing pain and functional limitations. The condition affects mainly the hands, spine, and weight-bearing joints such as the hips, knees and ankles.
(More? 2009 Lecture - Musculoskeletal)

osteoblast

The mesenchymal cells that first differentiate to form the cellular component of bone and produce bone matrix. Osteoblast mature to form osteocytes. Pluripotent mesenchymal stem cells are the common mesenchymal progenitor for several different cell types including: osteoblasts, chondroblasts, muscle, bone marrow stromal cells and adipocytes. Osteoblasts express alkaline phosphatase, collagens and non-collagen bone matrix proteins (osteocalcin) and hormone receptors (PTH, 1,25-dihydroxyvitamin D3, estrogen, glucocorticoids).
(More? 2009 Lecture - Musculoskeletal | Medicine Practical - Bone Development | Musculoskeletal Development - Bone)

osteochondroma

The most common benign bone tumor occuring mainly at the metaphyseal region of the long bones. The tumor is slow-growing and painless, forming a cartilage-capped bony outgrowth on the surface of the bone in children and adolescents.
(More? Musculoskeletal Development - Bone)

osteoclast

Cells that remove bone (bone resorption) by enzymatically eroding the bone matrix. These cells are blood cell (monocyte-macrophage) in origin and fuse to form a multinucleated osteoclast. These cells allow continuous bone remodelling and are also involved in calcium and phosphate metabolism. The erosion cavity that the cells lie iwithin and form is called Howship's lacuna. Osteoclasts express a number of proteolytic Matrix MetalloProteinases (MMPs) including MMP-9, MMP-10, MMP-12 and MMP-14.
(More? 2009 Lecture - Musculoskeletal | Medicine Practical - Bone Development | Musculoskeletal Development - Bone | Cardiovascular System - Blood)

osteocyte

The mature bone-forming cell, which form the cellular component of bone and produce bone matrix. These cells differentiate from osteoblasts, mesenchymal cells that first differentiate to initially form bone.
(More? 2009 Lecture - Musculoskeletal | Medicine Practical - Bone Development | Musculoskeletal Development - Bone)

osteon

The anatomical (histological) unit structure (principal structure) of compact bone.
(More? 2009 Lecture - Musculoskeletal | Musculoskeletal Development - Bone)

osterix

(Osx) osteoblast-specific transcription factor required for osteoblast differentiation, which inhibits the Wnt pathway activity.
(More? 2009 Lecture - Musculoskeletal | Bone Development | Molecular Development)

otitis media

The fluid in the middle ear accompanied by signs and symptoms of ear infection. Common developmental problem, prolonged or repeated occurance can lead to developmental delay in learning, speech and even damage to the middle ear structures.
(More? 2009 Lecture - Hearing | Senses Notes | Hearing Abmnormalities)

otic vesicle

(otocyst) The sensory otic placode forming as a pair on the surface of the developing head, which sinks into mesoderm to form spherical vesicle (stage 13/14 embryo) that will form the membranous labyrinth (cochlea, semi-circular canals) and cranial nerve (CN VIII) components of the inner ear.
(More? 2009 Lecture - Hearing | Organs of Audition and Equilibrium | Senses Notes)

otocyst

(otic vesicle) The sensory otic placode forming as a pair on the surface of the developing head, which sinks into mesoderm to form spherical vesicle (stage 13/14 embryo) that will form the membranous labyrinth (cochlea, semi-circular canals) and cranial nerve (CN VIII) components of the inner ear.
(More? 2009 Lecture - Hearing | Organs of Audition and Equilibrium | Senses Notes)

otolith

(statoconium, otoconium) A calcium carbonate concretion found within the otolitic membrane of the utricle and saccule in the vestibular portion of inner ear, that functions with balance.
(More? 2009 Lecture - Hearing | Organs of Audition and Equilibrium | Senses Notes)

otolithic membrane

The extracellular matrix that cover the sensory epithelia of the inner ear. This membrane within the utricle and saccule contain embedded hair cell cilia and small crystalline bodies of calcium carbonate (otoliths) that functions to detect head motion.
(More? 2009 Lecture - Hearing | Organs of Audition and Equilibrium | Senses Notes)

otopharyngeal tube

(auditory tube, eustacian tube, pharyngotympanic tube) A narrow canal connecting the middle ear space to the back of the oral cavity. The tube allows ventilation protection and clearance for the middle ear cavity. Ventilation is the pressure equalization in the middle ear. Clearance is to allow fluid drainage from the middle ear. Embryonic origin is from the first pharyngeal pouch. In development, the canal is initially both horizontal, short and very narrow leading to poor drainage and easy blockage.
(More? 2009 Lecture - Hearing | Middle Ear | Hearing Notes | Abnormal Hearing Notes)

Otx2

The paired type homeobox gene identified in many species which has a role in early head and brain development.
(More? OMIM - Otx2)

outer hair cells

(OHCs) Within the cochlea, the three rows of hair cells that function to increase basilar membrane motion through a local mechanical feedback process within the cochlea, the "cochlear amplifier".
(More? 2009 Lecture - Hearing)

outer pillar cells

Within the cochlea, cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells.
(More? 2009 Lecture - Hearing)

outer submucous plexus

(OSP, Meissner's plexus, plexus submucosus externus , Schabadasch plexus) A gastrointestinal tract intrinsic neral network, that is one of the two (inner and outer) lying within the submucosa involved in intestinal secretion and gut motility in large mammals. Smaller animals have only a single submucous plexus.
(More? Gastrointestinal Tract Notes)

ovarian factor

A cause of infertility due to problems with egg production by the ovaries.
(More? Week 1 - Oogenesis)

ovarian hyperstimulation syndrome

(OHSS) Condition associated with fertility drugs used for in vitro fertilization and other reproductive abnormalities. The drugs stimulate follicular development and oocyte maturation, there are no agreed standards for reporting this condition. Australian data shows "OHSS occurred in 0.8% of cycles that involved an oocyte retrieval with the incidence of OHSS increasing with the number of oocytes collected" (Wang YA, Chambers GM, Dieng M & Sullivan EA 2009. Assisted reproductive technology in Australia and New Zealand 2007. Assisted reproduction technology series no. 13. Cat. no. PER 47. 
Canberra: AIHW).
(More? Week 1 - In Vitro Fertilization | Medlineplus - OHSS | reproductive technology in Australia and New Zealand 2007)

ovarian monitoring

The use of ultrasound and/or blood or urine tests to monitor ovarian follicle development and hormone production.
(More? Week 1 Notes | Week 1 - Oogenesis)

ovarian stimulation

The use of drugs to stimulate the ovaries to develop follicles/eggs.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis | Human Menstrual Cycle)

ovary

The two female gonads where female germ cells (oocytes, eggs) are generated and also the source of estrogen and progesterone the female hormones regulating secondary sex characteristics and menstrual cycle uterine changes. The ovary is embryonically formed from primordial germ cells entering region of the paired mesonephric ducts (Wolffian ducts) which are lost in females.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 Notes | Week 1 - Oogenesis)

oviduct

(uterine horn, fallopian tube, oviduct, salpinx) see uterine tube. A pair of tubular structures designed to transport the oocyte (egg) from the ovary to the uterus body.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis | Week 1 Notes | Blue Histology - Female Reproductive System)

ovulation

The term used to describe the process of the mature follicle releasing the oocyte or ovum (and support cells) from the ovary surface into the peritoneal cavity. In humans, generally a single oocyte is released from a cohort of several maturing follicles. More than one follicle may be released (superovulation) following reproductive therapeutic treatment.
(More? 2009 Lecture - Cell Division and Fertilization | 2009 Lecture - Genital Development | Week 1 - Oogenesis | Week 1 Notes)

oxycephaly

(oxycephalus, "tower skull")Skull defect resulting from premature coronal suture synostosis. One of several skull deformities (scaphocephaly, oxycephaly, plagiocephaly, trigoncephaly) caused by premature fusion (synostosis) of different developing skull sutures.
(More? Skull Notes | Head Notes)

oxytocin

(Greek, "quick birth") An 8 amino acid peptide hormone released from the maternal posterior pituitary, involved in initiation and maintenance of birth labor by acting on the myometrium.
(More? Normal Development - Birth | Birth Overview )

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

What Links Here?
© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link | Original P

p

A prefix combined with a number to indicate a protein of a specific molecular size (mass). Often given initially if no specific "name" has been given to the protein, see examples in the following entries.

p16

a cell cycle protein in mammals that suppresses G1-Cdk activity in G1 and is frequently inactivated in cancer. Belongs to a class of Cdk inhibitory proteins. Nomenclature is p for protein and 16 is molecular size (16,000 daltons).
(More? Week 1 Mitosis | OMIM Entry for p16)

p53

(recently renamed tp53) A cell cycle related transcription factor that promotes transcription of genes that induce cell cycle arrest or apoptosis in response to DNA damage or other cell stresses. This tumor suppressor gene is mutated in about half of all human cancers. Nomenclature is t for tumor, p for protein and 53 is molecular size (53,000 daltons).
(More? Week 1 Mitosis | OMIM Entry for p53)

p63

a p53 related transcription factor and is essential for the development of stratified epithelia. p63 acts as a "master regulator" controlling stratified epithelial development program, through induction of downstream signals important for epithelial function. Nomenclature is p for protein and 63 for the molecular size (63,000 daltons).
(More? Reference: R.A. Ihrie etal., Perp Is a p63-Regulated Gene Essential for Epithelial Integrity See also : OMIM Entry for p63)

pain

A a complex neurological response to a range of stressful or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."

palatal rugae

(rugae palatinae) The transvere ridges forming on the secondary palate which are also sequentially added during development as the palate grows. Their number and arrangement on the hard palate of mammals is species specific. Along with the teeth and the tongue these ridges function in the process of mastication.
(More? Face Notes | Face - Abnormalities | Head Notes | Medline Plus - Cleft Lip and Palate)

palate

The roof of the mouth (oral cavity) a structure which separates the oral from the nasal cavity. Develops as two lateral palatal shelves which grow and fuse in the midline. Initally a primary palate forms with fusion of the maxillary processes with the nasal processes in early face formation. Later the secondary palate forms the anterior hard palate which will ossify and separate the oral and nasal cavities. The posterior part of the palate is called the soft palate (velum, muscular palate) and contains no bone. Abnormalities of palatal shelf fusion can lead to cleft palate.
(More? Face - Abnormalities | Face Notes | Head Notes | Medline Plus - Cleft Lip and Palate)

palatogenesis

The process of palate formation, divided into primary and secondary palate development.
(More? Face - Abnormalities | Face Notes | Head Notes | Medline Plus - Cleft Lip and Palate)

pancreas

The gastrointestinal tract associated organ with both exocrine (pH change and digestive enzyme secretion) and endocrine (hormone secretion) functions. In humans, the pancreas develops at the foregut/midgut junction (the septum transversum) and initially form connected to the gastrointestinal tract as two pancreatic buds (dorsal and ventral endoderm) which later fuse to form a single organ. The pancreas exocrine function (alkylate acidic stomach contents and amylase protein digestion) begins mainly fter birth. The endocrine function (alpha cell - glucagon, delta cell - somatostatin, beta cell - insulin) can be measured from 10 to 15 weeks onward.
(More? Gastrointestinal Tract - Pancreas | Endocrine Development - Pancreas)

pancreatitis-associated protein -III

(PAP-III) a macrophage chemoattractant, implicated in nerve regeneration as it has been shown to be induced and released from injured nerves. Journal of Neuroscience Paper

Paneth cell

a differentiated cell type cell within the gastrointestinal system epithelium. Paneth cells are located at the bottom of crypts of Lieberkühn in the small intestine. Their role is to control of infections by release of several antibacterial substances, including lysozyme. Paneth cell differentiation and positioning is apparently controlled by the developmental signaling protein Wnt.
(More? Gastrointestinal Tract Notes | Molecular Notes | Wnt7a)

Panton-Valentine leucocidin toxin

(PVL) produced by about 2% of Staphylococcus aureus (S aureus) bacteria, occurs very rarely and can be fatal in neonates.
(More? Abnormal Development - Bacterial Infection)

PAPP-A

acronym for pregnancy-associated plasma protein-A. Protein produced by both embryo and placenta during pregnancy. Maternal serum concentrations are related to subsequent fetal growth and it is thought to have several different functions, including preventing recognition of the fetus by the maternal immune system.
(More? pregnancy-associated plasma protein-A)

paramesonephric duct

(also called Mullerian duct) (Greek, para = "beside") The paired ducts that lie beside the mesonephric ducts, that will differentiate in the female embryo to form the female internal genital tract (uterine tubes, uterus, upper vaginal canal).
(More? Urogenital Notes)

paranasal sinuses

Air-filled cavities surrounding the nasal cavity and open into it, which combine in function to: reduce skull weight, produce mucus, and act as resonating chambers affecting voice quality. Located within in the frontal, maxilae, ethmoid, and sphenoid bones with the same name as the bones in which they are located.
(More? Respiratory Notes)

parasagittal

(Latin, sagitta = "arrow") The sagittal plane (ventro-dorsal) sections away from the midline (median plane or mid-sagittal) taken through the body.

parathyroid hormone-related protein

(PTHrP) A protein hormone produced by many fetal tissues and with a number of different functions including endochondral bone development, tooth development, and mammary gland epithelial-mesenchymal developmental interaction. Also suggested to have an autocrine role in lung development.
(More? Parathyroid Notes | Respiratory Notes)

paratubal musculature

The muscles lying beside the auditory (Eustachian) tube. consisting of the tensor veli palatini (TVP) and tensor tympani muscles.
(More? 2009 Lecture - Hearing)

paraxial mesoderm

The two lateral strips of mesoderm lying beside the axial mesoderm (notochord). This mesoderm at the body level will segment into [S.htm#somite somites], at the head level it remains unsegmented.
(More? Musculoskeletal Notes | Week 3 Notes)

parenchyma

(Greek, enkeim = "to pour in") Term used to describe the cells forming the functional cells of an organ or tissue. These cells carry out the function of the organ at a cellular level. Within the organ, the other population of cells, [S.htm#stroma stroma], are structural cells, connective tissue, the non-cellular extracellular matrix.

parietal pleura

Serous membrane which forms the outer lining of pleural cavity. mesoderm of the thoracic cavity body wall and derived from epithelia of pericardioperitoneal canals from intraembryonic coelom. The inner pleural layer, visceral pleura, is splanchnic mesoderm in origin.
(More? Respiratory Notes)

Parkinson's disease

(paralysis agitans, shaking palsy) A postnatal neurological disease of the central nervous system, typically in ageing and more common in men than in women. The neurons affected are those in the brain that control muscle movement and have dopamine as their neurotransmitter. Named after James Parkinson (1730-1813), an English physician who made the detailed description of the disease in "An Essay on the Shaking Palsy" (1817).
(More? Neural Notes | Neural Abnormalities | Medline Plus - Parkinson's Disease | Pearce JM. Aspects of the history of Parkinson's disease. J Neurol Neurosurg Psychiatry. 1989 Jun;Suppl:6-10)

pars

(Latin, pars = part of) Anatomical term describing something as part of an organ or tissue.

parthenogenesis

(Greek, parthenos = virgin, genesis = birth) The development of an unfertilized egg (no sperm). Occurs mainly in plants but can also occur in animals.
(More? Week 1 Abnormalities | Molecular Development - Epigenetics - Parthenogenesis)

partial androgen insensitivity

A genetic disorder causing ambiguous genitalia in 46,XY individuals. This X-linked disease is due to an absence or deficiency of androgen receptors in the androgen target tissues (e.g. genital skin region).
(More? Reproductive System - Abnormalities)

parturition

(Latin, parturitio = childbirth) term used to describe the process of childbirth.
(More? Parturition Notes)

parvovirus

(Latin, parvo = poor) A family of viruses that infect many species. Human parvovirus B19 (a single-strand 5,594 nucleotide DNA Class II virus) infection is also called "fifth disease" and occurs mainly in children. Animal parvoviruses do not infect humans.
(More? Defect - Parvovirus)

passive immunity

(maternal passive immunity) Term used to describe the transfer of antibodies from one person to another, this can occur artificially or by maternal transfer (maternal passive immunity) to the fetus and neonate.
(More? Placenta | Normal Development - Milk)

patched receptor

A membrane protein that binds the signaling factor sonic hedgehog during development.
(More? Sonic hedgehog)

Pax

The name derived from Drosophila gene "paired" (prd) with a box domain. A transcription factor of the helix-turn-helix structural family, DNA binding, and activating gene expression. In human, there are nine member proteins from Pax-1 to Pax-9.
(More? Molecular Factors - Pax | Molecular Notes)

PCB

Acronym for polychlorinated biphenyls, a class of chemicals linked to developmental defects.
(More? Defects - Chemical Notes)

PCB153

(2,2,4,4,5,50-hexachlorobiphenyl) A form of polychlorinated biphenyls, a class of chemicals linked to developmental defects.
(More? Defects - Chemical Notes)

Peabody Developmental Motor Scale II

(PDMS-2) An early postnatal neurological assessment scale used in screening and diagnosis of neural development.
(More? Neural Notes | Postnatal Development)

parenchymal

(parenchyma) Histological term used to describe the functional cells of an organ, tissue or structure. The term is often paired with stromal (stroma), which describes the supportive cells within an organ, tissue or structure.

pedicle

(Latin, pediculus = small foot) Region of the vertebra, forming the vertebral arch portion between the transverse process and the vertebral body.

perichondrium

The undifferentiated mesenchymal cells which surround the growth plate cartilage and regulate chondrocyte differentiation. Involved with endochondral bone formation process.
(More? Bone Notes)

pericyte

The smooth muscle-like cell which covers over blood vessel endothelial cells.
(More? Cardiovascular Notes | Lymphatic Notes)

perinatal

The early postnatal period relating to the birth, statistically it includes the period up to 7 days after birth.
(More? Normal Development - Birth)

perinatal mortality ratio

A statisical term which refers to the sum of late fetal deaths plus infant deaths within 7 days of birth divided by the number of live births, per 1,000 live births.
(More? Normal Development - Birth | Statistics | Australian Statistics)

perinuclear theca

The region located in the sperm head perinuclear region, containing a cytoskeletal element to maintain the shape of the sperm head and functional molecules leading to oocyte activation during fertilization.
(More? Spermatogenesis | Fertilization)

periosteum

fibrous membrane covering bone except on the surface of joints which are covered in articular cartilage.
(More? Musculoskeletal Notes | Bone Notes)

perisylvian cortex

The region of the cortex (frontal and posterior) involved in the human cognitive specializations which include language. The perisylvian region for language is also asymmetrically represented in the area of left hemisphere. The posterior perisylvian superior temporal gyrus (STG)
(More? Neural Notes | PMID: 17978184)

pericardial cavity

The anatomical body cavity in which the heart lies. The pericardial cavity forms in the lateral plate mesoderm above the buccopharyngeal membrane, as part of the early intraembryonic coelom. This cavity is initially continuous with the two early pleural cavities. Note the single intraembryonic coelom forms all three major body cavities: pericardial cavity, pleural cavity, peritoneal cavity.
(More? Coelomic Cavity Notes | GAstrointestinal Tract Notes)

peritoneal cavity

The anatomical body cavity in which the lower body organs lie: intestines, liver, bladder, uterus, ovary. The peritoneal cavity forms initially from two separate regions of the early intraembryonic coelom (formed in the lateral plate mesoderm), which with embryo folding, fuse to form a single cavity. Note the single intraembryonic coelom forms all three major body cavities: pericardial cavity, pleural cavity, peritoneal cavity.
(More? Coelomic Cavity Notes | Gastrointestinal Tract Notes)

peritubular cells

(peritubular myoid cells) stromal cells (mesenchymal) located in the male gonad (testis) seminiferous tubule lying outside the basal membrane in the lamina propria surrounding seminiferous tubulus that regulate Sertoli cell function and contractility of seminiferous tubules. Also used to describe cells found in the kidney glomerulus.
(More? Week 1 - Spermatogenesis)

perivitelline space

(PVS) space between the oocyte (egg) and the surrounding zona pellucida, enlarged in the region where the polar body lies. In mice this has been shown to influence the site sperm entry independent of any asymmetry of the oocyte membrane.
(More? Week 1 - Fertilization | PMID: 16620153)

perlecan

(heparan sulfate proteoglycan 2) An extracellular matrix proteoglycan expressed in the basal lamina of the neuroepithelium.
(More? Neural Notes | Extracellular Matrix Lecture)

Persistent Pulmonary Hypertension of the Newborn

(PPHN) A serious newborn condition due to due to the failure of closure one of the prenatal circulatory shunts, the ductus arteriosus. Occurs in about 1-2 newborns per 1000 live births and results in hypoxemia.
(More? Respiratory Development - Birth)

persistent truncus arteriosus

A developmental heart (cardiac) abnormality (1 to 2% of all heart defects) , where the truncus arteriosus fails to divide into aorta and pulmonary artery. The defect also involves a ventricular septal defect and can be associated with DiGeorge syndrome or velocardiofacial syndrome.
(More? Heart Abnormalities | Heart Notes)

Peyer's patches

The Gut-Associated Lymphoid Tissue (GALT) located in the ileum and appendix (lying between the lamina propria to the submucosa). These immune system structures are the first line of protection against ingested infectious agents.
(More? Gastrointestinal Tract Notes)

PGC

An acronym for Primordial Germ Cell, the embryonic cell that will form eventually either egg or sperm cell.
(More? Genital Notes | primordial germ cell movies)

PGD

Acronym for Pre-implantation Genetic Diagnosis, a screening procedure for embryos produced through in vitro fertilisation (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.
(More? Week 1 Notes | In Vitro Fertilization Notes)

pharyngeal arch

(branchial arches, Greek, branchial = gill) These are a series of externally visible anterior tissue bands lying under the early brain that give rise to the structures of the head and neck. In humans, five arches form (1,2,3,4 and 6) but only four are externally visible on the embryo. Each arch has initially identical structures: an internal endodermal pouch, a mesenchymal (mesoderm and neural crest) core, a membrane (endoderm and ectoderm) and external cleft (ectoderm). Each arch mesenchymal core also contains similar components: blood vessel, nerve, muscular, cartilage. Each arch though initially formed from similar components will differentiate to form different head and neck structures.
(More? Head Notes | Face Notes |Neural Crest Notes | Endocrine Notes)

pharyngeal arch artery

Each early developing pharyngeal arch contains a lateral pair of arteries arising from the aortic sac, above the heart, and running into the dorsal aorta. later in development these arch arteries are extensively remodelled to form specific components of the vascular system. Pharyngeal Arch 1 arteries are mainly lost and forms part of maxillary artery. Pharyngeal Arch 2 arteries remains to form the stapedial arteries. Pharyngeal Arch 3 arteries forms the common carotid arteries, internal carotid arteries in the neck. Pharyngeal Arch 4 arteries will form part of aortic arch (left arch artery) and part right subclavian artery (right arch artery) Pharyngeal Arch 6 arteries form part of left pulmonary artery (left arch artery) and part of right pulmonary artery (right arch artery).
(More? Cardiovascular Notes | Head Notes | Face Notes)

pharyngeal arch cartilage

Each early developing pharyngeal arch contains a horseshoe shaped band of cartilage that acts as a template and contributes to the development of head and neck bony and cartilagenous features, including the middle ear bones. Pharyngeal Arch 1 cartilage (Meckel’s cartilage) dorsal ends form malleus and incus midpart forms ligaments (ant. malleus, sphenomandibular) ventral part forms mandible template. Pharyngeal Arch 2 cartilage (Reichert’s cartilage) dorsal ends form stapes and Temporal bone styloid process, ventral part ossifies to form hyoid bone components, lesser cornu and superior body. Pharyngeal Arch 3 cartilage forms hyoid components, greater cornu and inferior part of hyoid. Pharyngeal Arch 4 and 6 cartilage forms laryngeal cartilages except epiglottis (from hypobranchial eminence).
(More? Middle Ear Notes | Head Notes | Face Notes)

pharyngeal arch nerve

Each early developing pharyngeal arch contains the developing cranial nerves, as a pair, within the arch mesenchyme. Each cranial nerve is numbered (roman numeral) in rostrocaudal sequence and also has a specific name. The cranial nerve within each arch often relates to the other structures formed from taht arch. Pharyngeal Arch 1 contains the trigeminal nerve (CN V, cranial nerve 5). Pharyngeal Arch 2 contains the facial nerve (CN VII, cranial nerve 7). Pharyngeal Arch 3 contains the glossopharyngeal nerve (CN IX, cranial nerve 9) Pharyngeal Arch 4 and 6 contains the Vagus (CN X cranial nerve 10), forming the adult superior laryngeal and recurrent laryngeal branches.
(More? Neural Notes | Neural Crest Notes | Head Notes | Face Notes)

pharyngeal arch pouch

An out-pocketing of the endoderm lined pharynx occurring between each developing pharyngeal arch. Each of the pharyngeal arch pouches contributes different components of the head and neck, either cavities or endocrine tissues. Pharyngeal Arch 1 pouch elongates to form tubotympanic recess tympanic cavity, mastoid antrum and auditory tube (Eustachian tube). Pharyngeal Arch 2 pouch forms the tonsillar sinus and is later mostly oblierated by palatine tonsil. Pharyngeal Arch 3 pouch forms the inferior parathyroid and thymus. Pharyngeal Arch 4 pouch forms the superior parathyroid, parafollicular cells of Thyroid.
(More? Middle Ear Notes | Thymus Notes | Parathyroid Notes | Thyroid Notes | Endocrine Notes | Head Notes | Face Notes)

pharyngotympanic tube

(auditory tube, eustacian tube, otopharyngeal tube) A narrow canal connecting the middle ear space to the back of the oral cavity. The tube allows ventilation protection and clearance for the middle ear cavity. Ventilation is the pressure equalization in the middle ear. Clearance is to allow fluid drainage from the middle ear. Embryonic origin is from the first pharyngeal pouch. In development, the canal is initially both horizontal, short and very narrow leading to poor drainage and easy blockage.
(More? Middle Ear | Hearing Notes | Abnormal Hearing Notes)

pharynx

(throat) Forms the initial segment of the upper respiratory tract divided anatomically into three regions: nasopharynx, oropharynx, and laryngopharynx (hypopharynx). Anatomically extends from the base of the skull to the level of the sixth cervical vertebra.
(More? Respiratory Notes)

phenylketonuria

(PKU) A disease resulting from an inability to break down phenylalanine, an amino acid. Causes mental and motor retardation, microcephaly, poor growth rate and seizures. Can be tested in newborn screening.
(More? Neonatal Screening)

pheromone

A secreted chemical in sweat or urine that causes specific physiological response in other members of the same species.
(More? Mouse Development- Estrous Cycle)

phocomelia

(Greek, phoco = seal, melia = limb) a flipper-like appendage attached to the trunk, as described in the original classical classification of limb deficiencies. Seen in genetic and environmentally derived abnormalities, for example in association with thalidomide.
(More? Limb Abnormalities - Classification)

PlGF

Acronym for Placental Growth Factor a vascular endothelial growth factor (VEGF) released from the placental trophoblast cells and other sources.

pineal gland

The central nervous system endocrine gland named as the organ shape resembled a pine cone. Embryonic origin is from a dorsal outpocket of diencephalon. The hormone melatonin (high in dark, low in day) involved with the diurnal cycle, inhibits pituitary-gonad axis.
(More? Endocrine Notes | Pineal Gland)

Pink Disease

A chronic mercury poisoning in infants and young, also called acrodynia (Greek, acrodynia = painful extremities)
(More? acrodynia | Heavy metals | Michigan Health MercurySpillFactsheet_85689_7.pdf)


pituitary gland

(hypophysis) An endocrine organ.
(More? Lecture - Endocrine Development)

pharynx

The uppermost end of gastrointestinal and respiratory tract, in the embryo beginning at the buccopharyngeal membrane and forms a major arched cavity within the phrayngeal arches.
(More? Head Notes | GIT Notes | Carnegie stage 13 pharynx)

PKU

An acronym for the disease phenylketonuria that can be detected by a neonatal blood test (Guthrie).

placenta

(Greek, plakuos = flat cake) The developmental organ formed from maternal and fetal contributions in animals with placental development. In human, the placenta at term is a discoid shape "flat cake" shape; 20 cm diameter, 3 cm thick and weighs 500-600 gm. Placenta are classified by the number of layers between maternal and fetal blood (Haemochorial, Endotheliochorial and Epitheliochorial) and shape (Discoid, Zonary, Cotyledenary and Diffuse). The placenta has many different functions including metabolism, transport and endocrine.
(More? ANAT2341|Lecture Placenta Development | Placenta Notes)

placental cord

The placental cord is the structure connecting the embryo/fetus to the placenta. It is initially extra-embryonic mesoderm forming the connecting stalk within which the placental blood vessels (arteries and veins) form. In human placental cords the placental blood vessels are initially paired, later in development only a single placental vein remains with a pair of placental arteries. This structure also contains the allantois, an extension from the hindgut cloaca then urogenital sinus. Blood collected from the placental cord following delivery is a source of cord blood stem cells.
(More? ANAT2341 - Lecture Placenta Development)

placental growth factor

(PlGF) A growth factor of the vascular endothelial growth factor (VEGF) family, released from the placental trophoblast cells and other sources that stimulates blood vessel growth.

placenta accreta

The abnormal placental adherence, either in whole or in part of the placenta with absence of decidua basalis, leading to retention as an after-birth to the underlying uterine wall. The incidence of placenta accreta also significantly increases in women with previous cesarean section compared to those without a prior surgical delivery.
(More? ANAT2341 - Lecture Placenta Development | Abnormal Placenta Notes)

placental malaria

malarial infection of the placenta by sequestration of the infected red blood cells. Common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).
(More? Abnormal Development | Brown University Maternal Malaria)

placentophagia

Term used to descrbe the maternal ingestion of afterbirth materials (placental membranes and amniotic fluid) that can occur following mammalian parturition (birth).

placode

(Greek, plax = "plate" or "scale", eidos = shape or form) A surface ectoderm thickening seen in the early embryo head region either sensory or neurogenic or the adenohypophyseal placode. Each pair of placodes will contribute a different component of each sensory system (otic placode, optic placode, nasal placode) and neurons in the trigeminal (CN V), facial (CN VII), glossopharyngeal (CN IX), and vagal (CN X) cranial ganglia. The adenohypophyseal placode will form the endocrine anterior pituitary. Note that the glial component of all cranial ganglia is neural crest in origin.
(More? Head Notes)

plagiocephaly

one of several skull deformities (scaphocephaly, oxycephaly, plagiocephaly, trigoncephaly) caused by premature fusion (synostosis) of different developing skull sutures. Plagiocephaly results from asymmetric coronal suture synostosis.
(More? Skull Notes | Head Notes)

plagiopatagium

is the thin skin membrane (extending from the fifth digit and the posterior aspect of the forelimb, along the side of the body, to the anterior aspect of the hindlimb) forming the bat wing.
(More? Other Embryos - Bat)

Plan B

A two pill high dose regimen of the oral contraceptive levonorgestrel, 90% effective in preventing pregnancy when taken within 72 hours of unprotected sex. Approved for use in some countries, but not the USA as it is considered an abortifacient not a contraceptive. US Food and Drug Administration: September 2006 - approved the emergency contraceptive Plan B for sale over the counter to women aged 18 or over. April 2009 - would accept and not appeal against a New York federal court decision that 17 year old women should be able to buy the emergency contraceptive pill Plan B without a prescription.
(More? Human Menstrual Cycle - Birth Control)

plasma cell

A cell in the blood, the active B cell (lymphocyte) which is secreting antibody. Located in either bone marrow or peripheral lymphoid tissues, these cells have and increased cytoplasmic volume (due to increase rough endoplasmic reticulum) in comparison to the inactive (non-secreting) lymphocyte.
(More? Cardiovascular System - Blood | Cardiovascular System Development - Lymphatics)

Plasmodium falciparum

The microorganism that acts as a malarial parasite and can cause placental malaria.
(More? Placental Abnormalities | Abnormal Development - Maternal)

pleural cavity

Anatomical body cavity in which the lungs develop and lie. The pleural cavity forms in the lateral plate mesoderm as part of the early single intraembryonic coelom. This cavity is initially continuous with pericardial and peritoneal cavities and later becomes separated by folding (pleuropericardial fold, pleuroperitoneal membrane) and the later formation of the diaphragm. The pleural cavities form initially as two narrow canals. Note the single intraembryonic coelom forms all three major body cavities: pericardial cavity, pleural cavity, peritoneal cavity.
(More? Respiratory Notes | Coelomic Cavity Notes)

pleuropericardial fold

(pleuropericardial membrane) An early embryonic fold which restricts the communication between pleural cavity and pericardiac cavity, contains both the cardinal vein and phrenic nerve.
(More? Coelom Notes | Respiratory Notes)

pleuroperitoneal membrane

An early embryonic membrane that forms inferiorly at the septum transversum to separate the peritoneal cavity from the pleural cavity.
(More? Coelom Notes)

plexus

(Latin, plexus = a network) used anatomically to describe a network of interconnecting structures either nerves, blood vessels, or lymphatic vessels.

pluripotent

A stem cell term describing the ability of a stem cell to form (differentiate) into many different cell types. The term is often used in stem cell research instead of totipotent, which means that the stem cell can form all embryo cell types.
(More? Stem Cell Notes)

PMS

Acronym for Pre-Menstrual Syndrome

podocyte

(glomerular podocyte) Kidney epithelial cell type in the nephron (functional kidney unit) located in the glomerulus. Podocytes are at the filtration barrier between capillary blood and the nephron tubular system and function to ultrafiltrate blood, and support glomerular capillary pressures. The differentiation of podocytes involves the formation of cellular foot processes and then the slit membrane.
(More? Nephron Notes | Kidney Notes)

polar body

A small cytoplasmic exclusion body formed from the excess DNA formed during the egg meiotic cycle and following sperm fertilization. There are 2-3 polar bodies derived from the oocyte present in the zygote, the number is dependent upon whether polar body 1 (the first polar body formed during meiosis 1) divides during meiosis 2. This exclusion body contains the excess DNA from the reductive division (the second and third polar bodies are formed from meiosis 2 at fertilization). These polar bodies do not contribute to the genetic complement of the zygote, embryo or fetus. Recent research in some species suggest that the space formed by the peripheral polar body (between the oocyte and the zona pellucia) can influence site of sperm fertilization.
(More? Week 1 Notes)

polychlorinated biphenyls

PCBs, a class of chemicals linked to developmental defects.
(More? Defects - Chemical Notes)

Polycomb/Trithorax

(PRE/TREs) cis-regulatory DNA elements initiator elements and maintenance elements identified in drosophila development. They can activate or silence transcriptional state of associated genes for many cell generations (divisions).
(More? PubMed Review)

polysialic acid

(PSA) is a cell surface carbohydrate attached to neural cell adhesion molecule (NCAM) that regulates (inhibits) cell interactions. During development PSA has a role in promoting neural precursor cell migration and axon path-finding.
(More? PNAS Image)

Polycystic ovary syndrome

(PCOS) or Stein-Leventhal syndrome (1930s researchers) a metabolic syndrome with many other symptoms, ovarian cysts arise through incomplete follicular development or failure of ovulation.
(More? Urogenital Abnormalities)

polyestrous

Term used to describe animals which have an estrous cycle that continues throughout the year (cattle, pigs, mouse, rat). Other types of estrous cycles include: seasonally polyestrous animals (multiple estrous cycles only during certain periods of the year) and monestrous animals (have only one estrous cycle per year).
(More? Estrous Cycle)

polydactyly

(polydactylia or polydactylism) A developmental abnormality resulting in an additional fingers or toes. Occasional there is aslo a combination of polydactyly with syndactyly is known as polysyndactyly.
(More? Lecture - Limb Development | Limb Abnormalities)

polysyndactyly

An abnormal digit (finger or toe) development resulting in a combination of polydactyly (additional digit) with syndactyly (digit fusion).
(More? Lecture - Limb Development | Limb Abnormalities)

ponderal index

(PI) - Fetal calculation based upon the ratio of body weight to length PI = [weight (in g) x 100] √∑ [length (in cm)]
(More? Fetal Weight | Fetal Length | Fetal Notes)

positive predictive value

Prenatal diagnostic test term describing the probability that a congenital anomaly is present given that the prenatal screening test is positive.
(More? Prenatal Diagnosis)

posterior neuropore

(caudal neuropore) The initial opening at the spinal cord end or "tail end" of the neural tube before it closes (humans approximately 26 days post-fertilization). The opening at the other "head end" of the neural tube is the anterior neuropore. Failure of posterior neuropore to close can lead to the neural tube defect (NTD) spina bifida.
(More? 2009 Lecture - Early Neural Development | Neural Abnormalities | Neural Tube Defects)

postmature

A term used to describe infants born after 42 weeks clinical gestation. Normal clinical LPM gestation is 40 weeks (which is usually 36-38 weeks post-fertilization development) infants born before 37 weeks are called premature.
(More? Normal Development - Birth)

Pouch of Douglas

(rectouterine pouch or rectovaginal) A female anatomical region describing the portion of the peritoneal cavity lying between the back wall of the uterus and rectum.

PPHNA

Acronym for Persistent Pulmonary Hypertension of the Newborn.

PPM

Acronym for parts per million, used to describe chemical concentrations.
(More? Chemicals)

preantral follicle

(primary follicle) Term used to describe the developmental stage of ovarian follicle development following primordial in describing the sequence (primordial, preantral, antral) of follicle development within the ovary. In humans, a number of primordial follicles will begin to develop into preantral follicles (primary), some of which will then form antral follicles (secondary), with only a single antral follicle developing into the ovulating follicle (Graafian) each menstrual cycle.
(More? Week 1 - Oogenesis)

preauricular tag

The skin tags located in front of the external ear opening, are common in neonates and in most cases are normal, though in some cases are indicative of other associated abnormalities.
(More? 2009 Lecture - Integumentary Development | Lecture - Hearing Development)

precocial species

Newborn animals that are relatively mature and mobile from birth or hatching, for example guinea pigs and hoofed animals. (altricial is where newborns are immature and not motile).

preeclampsia

(toxemia, pregnancy-induced hypertension) Maternal abnormality with high blood pressure and protein in the urine which can occur during pregnancy and may lead to eclampsia, a serious maternal condition leading to seizures or coma.
(More? Placenta | Medline Plus - preeclampsia eMJA - Pre-eclampsia: a lifelong disorder)

pregnancy-associated plasma protein-A

(PAPP-A) This placental protein is thought to have several different functions, including preventing recognition of the fetus by the maternal immune system, matrix mineralization and angiogenesis. It is a member of the alpha-macroglobulin plasma protein family, which bind cytokines and specifically cleave a binding protein for insulin-like growth factors (IGF binding protein 4 protease) modulating cytokine activity. Detection of this protein is also used as a first and second trimester diagnostic test for Trisomy 21.
(More? Abnormal Development - Prenatal Diagnosis - PAPP-A | Abnormal Development - Trisomy 21 (Down Syndrome) | Placenta Notes)

pregnancy (clinical)

A pregnancy verified by the presence of a gestational sac on ultrasound.
(More? Week 1 Notes)

pre-implantation genetic diagnosis

(PGD) a screening procedure for embryos produced through in vitro fertilization (IVF) for genetic diseases that would generate developmental abnormalities or serious postnatal diseases. Embryonic cells are removed and screened for chromosomal disorders or genetic diseases before the embryo transfer.
(More? Prenatal Diagnosis | Week 1 Notes | In Vitro Fertilization Notes)

premature

The term used to describe infants born before 37 weeks. Normal clinical gestation is 40 weeks (which is usually 36-38 weeks embryonic development) infants born after 42 weeks clinical gestation are called postmature.
(More? Normal Development - Birth)

Pre-Menstrual Syndrome

(PMS) A diverse range of symptoms that appear before menstruation, which apparently occur due to changing levels of sex hormones (progesterone, estrogen) and progesterone's metabolite (alopregnanolone) during the menstrual cycle. The possible PMS symptoms: tiredness, depression, restlessness, insomnia, irritability, emotional, outbursts of anger, headache, dizziness, abdominal pain, breast pain, water retention, diarrhoea, increase in appetite and food craving (sugar, salt). Women can show some or all of these symptoms.
(More? Human Menstrual Cycle | ABC RN Monday 8 June 1998 - Premenstrual Syndrome)

prenatal screening sensitivity

(detection rate) Prenatal diagnostic test term describing the probability of testing positive on a prenatal screening test if the congenital anomaly is present.
(More? Prenatal Diagnosis)

prenatal screening specificity

Prenatal diagnostic test term describing the probability of testing negative on a prenatal screening test if the congenital anomaly is absent.
(More? Prenatal Diagnosis)

presentation

A birth term, referring to how the fetus is situated in the uterus at the time of birth.
(More? Normal Development - Birth)

presenting part

A birth term, referring to the part of fetus body that is closest to the cervix.
(More? Normal Development - Birth)

prevalence

A statistical term used mainly in studying disease/disorders and is a measure of the proportion of a population that are disease cases at a point in time. Generally used to measure only relatively stable conditions, not suitable for acute disorders.
(More? Abnormal Development)

primary brain vesicle

Term used to describe the developing cranial neural tube first expanded regions that will later form all the structures of the brain, the caudal remainder of the neural tube will form the spinal cord. The three primary brain vesicles are the: prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain).
(More? 2009 Lecture - Early Neural Development)

primary follicle

(preantral follicle) Term used to describe the developmental stage of ovarian follicle development following primordial in describing the sequence (primordial, primary, secondary) of follicle development within the ovary. In humans, a number of primordial follicles will begin to develop into primary follicles, some of which will then form secondary (antral follicle), with only a single antral follicle developing into the ovulating follicle (Graafian) each menstrual cycle.
(More? Week 1 - Oogenesis)

primary heart field

(PHF, first heart field, FHF) A mesodermal region that forms the early primary heart field and contribute specific components (left ventricle) of cardiac development (endocardium, myocardium, and smooth muscle). A later forming second heart field forms adjacently and contributes other cardiac structures. Recently suggested that this primary/secondary terminology should be replaced with gene specific expression domains or fields.
(More? Heart Notes)

primary organizer

The term used originally by Spemann to describe the dorsal lip of the blastopore, meaning that its action established the organization of the entire early embryo.
(More? 2009 Lecture - Week 3 Development | primitive node | Hans Spemann | Nobel Laureate- Hans Spemann)

primigravida

Clinical term for woman who is pregnant for the first time.

primitive node

(Hensen's node, primitive knot) The small circular region located at the cranial end of the primitive streak, where gastrulation occurs, and is a controller of this process. It is centered around the primitive pit, the site of epiblast extension cranially to form the initial axial process. Region is equivilant to the blastopore in amphibians.
(More? Carnegie Stage 7 | Week 3 Gastrulation | Neural Notes | Nobel Laureate- Hans Spemann)

primitive streak

Visible region on the surface of the early epiblast embryonic bilaminar disc, representing the site of cell migration during gastrulation (cell migration to form endoderm then mesoderm). The primitive streak extends centrally from the primitive node (Hensen's node) to the disc periphery near the connecting stalk. The orientation of the streak establishes the early body axis (rostro-caudal, head-tail). In the human embryo, gastrulation occurs from week 3 through to week 4.
(More? 2009 Lecture - Week 3 Development | Carnegie Stage 7 | Week 3 Gastrulation)

primordial

(Latin primordialis = origin, German, anlage) Term used to describe the earlier or primitive developmental state of a structure, tissue, organ or cell (-blast).

primordial follicle

Present in the ovary from birth, located in the stroma of the ovary cortex beneath the tunica albuginea. The primordial follicle is the oocyte and the surrounding follicular cells.
(More? Week 1 Notes)

primordial germ cell

Term used to describe the population of cells that will form either the spermatozoa progenitor in the embryonic testes or oocyte progenitor present in the primordial follicle ovary from birth, located in the stroma of the ovary cortex beneath the tunica albuginea. The primordial follicle is the ovary cortical structure containing the oocyte and the surrounding follicular cells.
(More? More? Week 1 Notes)

primordium

(Latin primordialis = origin, German, anlage) Term used to describe the earlier or primitive developmental state of a structure, tissue, organ or cell (-blast).

processus vaginalis

A transient communicating channel in testes development between tunica vaginalis and peritoneal cavity.
(More? testis descent image | Urogenital Notes)

progesterone

A steroidal hormone of the progestogens class, which has many roles in the female. Functions include regulation of the menstrual cycle, uterine changes, maintaining pregnancy and effects on systems throughout the body. Biological sources include: adrenal glands, gonads (corpus luteum), brain, and placenta. Male progesterone has a suggested role in neural development. Progesterone is also used clinically as a part of hormone replacement therapy (HRT) in women. The human progesterone receptor has two isoforms (PRA and PRB).
(More? Human Menstrual Cycle)

progestins

these compounds are synthetically produced progestogens used clinically and experimentally.
(More? Human Menstrual Cycle)

prolactin

(PRL) anterior pituitary hormone which stimulates breast development and milk production in pregnancy. Also has a role in regulating follicle stimulating hormone (FSH) effect on the ovary. Protein hormone is similar in structure to both growth hormone (anterior pituitary) and chorionic somatomammotropin (placenta). Anterior pituitary release of prolactin is in turn regulated by the hypothalamus prolactin-releasing hormone (PRLH, prolactin-releasing peptide). Recently been shown to to mimic in pregnancy effects of increased maternal myelination processes (oligodendrocyte precursor proliferation).
(More? Endocrine Development - Pituitary | Normal Development - Milk | OMIM - PRL)

prolactin-releasing hormone

(PRLH, prolactin-releasing peptide, PRRP) an 87 amino acid peptide hypothalamus hormone which regulates anterior pituitary release of prolactin.
(More? Endocrine Development - Hypothalamus | OMIM - PRLH)

pronephros

(Greek, pro = before) The first temporary stage of kidney development (pro-, meso-, meta-). This forms the kidney of primitive fish and lower vertebrates. Kidney development occurs within the intermediate mesoderm interacting with endoderm. In humans, this very rudimentary kidney forms very early at the level of the neck. It is rapidly replaced by the mesonephros, intermediate stage kidney, differentiating in mesoderm beneath.
(More? Urogenital Notes)

pronuclear fusion

(Greek, pro = before) The process of the fusion of the two haploid nuclear structures (pronuclei) contributed from the spermatazoa and oocyte to form the first diploid nucleus cell. Can also be called fusion of pronuclei.
(More? 2009 Lecture - Cell Division and Fertilization | Week 1 Notes)

pronucleus

(Greek, pro = before) The two haploid nuclear structures from spermatazoa and oocyte that will fuse together to form the first diploid nucleus cell. Therefore the nuclear structures that exist "before the nucleus", the plural term is pronuclei.
(More? Week 1 Notes)

propatagium

The thin skin membrane extending from the shoulder to the wrist anterior to the upper arm and forearm forming the leading edge of the bat wing.
(More? Other Embryos - Bat)

prophase

(Greek, pro = before) The first phase of mitosis, when the diffusely stained chromatin resolves into discrete chromosomes, each consisting of two chromatids joined together at the centromere.
(More? Week 1 Notes)

proprioception

(Greek, pro = before) The neurological sense of body position that is perceived both at the conscious and unconscious levels. There are a variety of peripheral specialized sensory structures that together provide the information on body position in space.
(More? Neural Notes)

proteasome

a large multiprotein complex found in all cells that functions in degradation of ubiquitylated proteins.
(More? UNSW Cell Biology)

proteinuria

The abnormal presence of protein in the urine and an indicator of diesease including diabetic kidney disease (DKD, diabetic nephropathy).
(More? Kidney Abnormalities)

protocadherin 15

(Pcdh15) A protein required for initial formation of stereocilia bundles and changes in the actin meshwork within hair cells. The Ames waltzer (av) mouse mutant has both auditory and vestibular abnormalities from a mutation in this gene.

prosencephalon

(forebrain) the most anterior neural tube primary brain vesicle (there are 3 primary brain vesicles) that will form the two secondary brain vesicles, telencephalon and diaencephalon. These generate in the adult brain the cerebral hemispheres (neocortex, basal nuclei, palaeocortex, archicortex) and thalmus, hypothalmus and other nuclei respectively. The prosencephalon lumen (cavity of the neural tube) will form the lateral and third ventricle.
(More? 2009 Lecture - Early Neural Development | Neural Notes | Ventricular System)

pruritus

(Latin, prurire = to itch) itching skin sensation which can have a number of different causes (diabetes, iron deficiency, hyperthyroidism, Hodgkin's Disease, hair loss, allergic drug reaction).
(More? 2009 Lecture - Integumentary Development | Skin Notes)

pseudohermaphrodite

(Disorder of Sex Development, DSD) A historic terminology no longer applied and replaced with the term Disorders of Sex Development (DSD). Humans having both male and female reproductive organs, occurs in both male and female forms.
46,XY DSD karyotype who have a predominantly female phenotype (blind-ending vagina, absence of breast development, primary amenorrhea, presence of testicular structures) that is with gonads of one sex, external genitalia of opposite.
46,XX DSD karyotype with gonads as ovaries, external genitalia ambiguous and hyperplastic adrenals secreting androgens.
Ovotesticular DSD
(More? Reproductive System - Abnormalities)

puberty

(Latin, pubertas = adulthood) The process involving maturation of the reproductive system and development of secondary sex characteristics. A complex process, initiated by an unknown mechanism, but involving the brain driving the hormonal axis.
(More? 2009 Lecture - Endocrine Development | 2009 Lecture - Genital Development | Endocrine Notes - Gonad | Puberty Notes)

puerperal

Term pertaining to childbirth or the period immediately following birth.
(More? Birth Notes)

puerperium

The six weeks following parturition (birth). Maternal reproductive organs and physiology return to pre-pregnant state.
(More? Birth Notes)

pyelectasis

The dilatation of the fetal renal pelvis (anteroposterior pelvic diameter >/=4 mm) visible with ultrasound.
(More? Kidney Notes | Movies - Abnormal Ultrasound)

pyknons

(Greek, pyknon = dense) term used to describe a DNA non-random pattern of repeated sequence elements identified in the human genome following computer analysis (genic and nongenic regions, patterns of 16+ bases in length, occurring 40+ times in nongenic). These sequences are: found frequently in the 3' untranslated regions (3'UTR) of genes, can be repeated with a regular spacing of 18 to 22 nucleotides between copies, and have currently an unknown function.

PV-1

A type II membrane glycoprotein component found in fenestrae and in caveolae.
(More? PMID: 10557298)

Glossary Comments

Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).

These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.

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Cite this page: Hill, M.A. (2019, September 16) Embryology Numbers. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Numbers

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