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)
Barker Hypothesis
original name for Fetal Origins 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)
Bartholin Gland
(= greater vestibular gland) female genital tract glands which secretes mucous. 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)
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)
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)
biotinidase
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
(BPD) diameter between the 2 sides of the head, used in clinical ultrasound measurements after 13 weeks (2.4 cm) to term (9.5 cm). (More? Ultrasound Movies)
birth
(parturition) pysiological process of offspring (child) being born. (More? Normal Development - Birth)
birth rate
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
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).
blastocyst
(Greek, blastos = sprout + cystos = cavity) The early stage in development before implantation, consists of outer trophoblast and inner cell mass. (More? (More? Week 1 - Blastocyst | Week 2 Notes)
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)
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).
Sangiorgi E, Capecchi MR. Bmi1 is expressed in vivo in intestinal stem cells. Nat Genet. 2008 Jul;40(7):915-20. (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)
bone
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 stromal cells
(BMSCs) 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)
Botallo's duct
another term for the ductus arteriosus, which is 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)
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
mixed spinal nerves innervating the upper limb form a complex meshwork (crossing). (More? Neural Notes)
brain
general term for the central nervous system formed from the 3 primary vesicles of the neural tube. (More? Neural Notes)
breech
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)
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)
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)
buccopharyngeal membrane
(oral membrane) (Latin, bucca = cheek) at cranial (mouth) end of gastrointestinal tract (GIT) where surface ectoderm and GIT endoderm meet. (see also cloacal membrane) (More? GIT Notes)
Bulbourethral Gland
(= Cowper's Gland) 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)
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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(*). |
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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. |
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