Acronym for Experimental Autoimmune Encephalomyelitis, an animal model of autoimmune demyelination diseases such as in immune encephalomyelitis and multiple sclerosis (MS)
Previously called blighted ovum or missed abortion, the term in fact generally describes embryo loss in first trimester.
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).
Acronym for ExtraCorporeal Membrane Oxygenation an invasive therapy that has been investigated and utilized in newborn infants with cardiorespiratory failure.
(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.
(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)
(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)
The term used to describe ectoderm derived neural crest which contributes in the head region skeletogenic mesenchyme (cartilage, bone, and connective tissue) which in the body region are typically derived from mesoderm.
(More? Neural Crest Notes)
A birth (parturition) term, referring to the shortening or thinning of the cervix, in preparation for birth.
(More? Normal Development - Birth)
(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.
(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)
(also called oocyte transfer) A clinical in vitro fertilization (IVF) technique to transfer of retrieved eggs into a woman's fallopian tubes through laparoscopy. This procedure is used only in gamete intrafallopian transfer (GIFT) (see definition).
(More? Week 1 - In Vitro Fertilization)
(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? human embryo)
(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.
(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).
Placement of embryosinto 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)
An anatomical description for a narrow extension from a larger structure. Synonyms: tuberosity, a protuberance.
The epithelial membrane lining the inside surface of heart.
(More? Heart Notes)
(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.
(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)
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)
(Greek, endon = within) A gland (organ, tissue) that is specialized for secretion of a hormone into the bloodstream for general circulation.
(More? Endocrine Notes)
(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.
(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.
(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)
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)
The epithelium lining of the non-pregnant uterus. During pregnancy this epithelium undergoes changes described as the decidual reaction and is renamed the "decidua".
(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).
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 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 endocrine disruptor, exposure in male children may delay sexual maturity and interfere with sex hormone synthesis.
(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.
A simple squamous epithelium lining blood vessels.
Acronym for enteric nervous system.
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.
(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)
Endocrine cells found within the epithelium of the gastrointestinal tract that secrete enterohormones.
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.
(Greek ependyma = upper cloak or garment) cell (ciliated squamous to columnar) epithelial membrane lining the cerebral ventricles (brain) and central canal (spinal cord).
(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)
(Greek, epi = above) The axis of a developing plant above the attachment point of the cotyledons.
(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.
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
(Greek, epi = above, upon) gene silencing that occur without changes in the genes (DNA) sequence, this changes can also be inherited.
(Greek, epi = above, upon) entire genome including silencing that occur without changes in the genes (DNA) sequence, this changes can also be inherited.
(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).
(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)
(Greek, epi = upon + thele = nipple) Cells tightly linked together to form a sheet with little extracellular matrix.
(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.
(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.
(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
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)
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).
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)
(E. coli) A common eubacterial resident of the human gut.
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)
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.
(French, etioler= to blanch or whiten) Having a thin, spindly appearance, poor leaf development, and no chlorophyll production.
(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.
(Greek, eu = true + karyon = nucleus) Referring to cells that contain a nucleus and other membrane bounded organelles. Note American spelling eucaryotic.
(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.
(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.
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)
The macromolecular complexe that post-transcriptionally regulate gene expression by degrading messenger RNAs.
A clinical term associated avoiding treatment and letting the miscarriage take its natural course, often associated wit first trimester miscarriage (early fetal loss).
(EAE) an animal model of autoimmune demyelination, such as in multiple sclerosis (MS).
(More? Gold R, Linington C, Lassmann H. Understanding pathogenesis and therapy of multiple sclerosis via animal models: 70 years of merits and culprits in experimental autoimmune encephalomyelitis research. Brain. 2006 Aug;129(Pt 8):1953-71.)
(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).
The canal from external ear (auricle) to the tympanic membrane (eardrum). Formed by the first pharyngeal cleft.
(More? Head Notes)
(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 zona pellucida. Extracellular matrix can be different in different tissues and consists of fibers (mainly collagen) and ground substance.
(EHBDs) Gastrointestinal term used to describe the liver and gall bladder hepatic, cystic, and common bile ducts.
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.
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.
(EVCTs) The trophoblasts which invade the uterine endometrium along with syncytiotrophoblasts and also secrete human chorionic gonadotropin hormone (hCG).
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).
(ECMO) an invasive therapy that has been investigated and utilized in newborn infants with cardiorespiratory failure.
(More? Bookshelf - HSTAT)
Search the NIH Medlineplus Medical Dictionary Type the word that you would like to find. If unsure of spelling, type the first few letters, followed by an asterisk(*).
Use this page to access brief definitions of specific alphabetically listed 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 Glossary List: Texts listed on page 1 Reading of each notes section, Department of Anatomy Publications, WWW resources from NCBI, AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn., NHMRC (Australia).
These notes are for Educational Purposes Only.
Please email Dr Mark Hill if you wish to make a comment about this current project.