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{{Glossary}} | [http://embryology.med.unsw.edu.au/Notes/Index/R.htm Original R]
{{Header}}


===raphe===
{{Glossary}}


:Anatomical line of fusion of the urogenital folds lying along the urethra and scrotum in male external genitalia.
==R==


:(More? [http://embryology.med.unsw.edu.au/Notes/urogen.htm Urogenital Notes])
===R-banding===


===Rathke's pouch===
:A genetics term used to describe a technique for staining chromosomes during [[M#metaphase|metaphase]]. The resulting banding pattern is the opposite of [[G#G-banding|G-banding]] and there are several other chromosome staining techniques.


:An ectodermal fold in roof of pharynx forming anterior pituitary (adenohypophysis) and pars intermedia. Named after German embryologist and anatomist Martin Heinrich Rathke (1793 -1860).
:(More? [[Molecular Development - Genetics]])


:(More? [http://embryology.med.unsw.edu.au/Notes/endocrine7.htm Pituitary Notes] | [http://embryology.med.unsw.edu.au/Notes/endocrine.htm Endocrine Notes] | [http://www.whonamedit.com/doctor.cfm/2955.html Martin Heinrich Rathke])
===radial hemimelia===


===rectouterine pouch===
:Clinical term for a congenital abnormality characterised by the partial or complete absence of the radius.


:(Pouch of Douglas or rectovaginal) Anatomical description of the female peritoneal cavity lying between the back wall of the [U.htm#uterus uterus] and rectum.
:(More? [[Musculoskeletal_System_-_Limb_Abnormalities|Limb Abnormalities]] | PMID 18950501)


===reductive division===  
===raphe===  


:Term describing meiosis where diploid DNA content becomes haploid (halved).
:Anatomical line of fusion of the [[U#urogenital fold|urogenital folds]] lying along the [[U#urethra|urethra]] and scrotum in male external genitalia.  


===Reichert's cartilage===
:(More? [[Genital System Development]])


:Neural crest forming the cartilage band of the second pharyngeal arch.
===Rathke's pouch===


:(More? [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes])
:An ectodermal fold in roof of [[P#pharynx|pharynx]] forming anterior pituitary (adenohypophysis) and pars intermedia. Named after German embryologist and anatomist Martin Heinrich Rathke (1793 -1860).  


===relative risk===


:(risk ratio or odds ratio) Term used in describing the effect of environmental teratogens on development. The ratio of the rate of the condition among the exposed and the non-exposed population. (e.g. smokers risk of having a low birth weight baby compared to non-smokers) A high relative risk may indicate a low absolute risk if the condition is rare. The other risk descriptor term used to describe the likelyhood of an abnormality is [A.htm#absolute_risk absolute risk].
:(More? [[Endocrine - Pituitary Development]] | [[Endocrine Development]] | [http://www.whonamedit.com/doctor.cfm/2955.html Martin Heinrich Rathke])


:(More? [http://embryology.med.unsw.edu.au/Defect/page1.htm#Environmental Abnormal Development - Environmental])


===relaxin===  
===Rauber's layer===


:The reproductive hormone involved in uterine relaxation (some species), reproductive tissue growth, connective tissue remodeling (collagen), cardiovascular, renal system, and brain. Relaxin receptor is G-protein-coupled receptor (relaxin family peptide receptors 1 - 4, RXFP1-4).  
:A thinned-out {{trophoblast}} membrane over the embryonic disk in developing carnivores and ungulates. In cattle, prevention of the loss of the polar trophoblast layer leads to ectopic domains of BRACHYURY, a gastrulation marker. Named after August A. Rauber (1841-1917) a German anatomist.


:(More?[http://embryology.med.unsw.edu.au/Notes/urogen.htm  Urogenital Notes])
:(More? {{trophoblast}} | [https://www.pnas.org/content/117/28/16409.abstract?etoc PNAS])


===renal===  
===receptor===
:General term generally for the cellular proteins which specifically bind a [[L#ligand|ligand]] or a number of ligands in signal transduction. Associated in many forms of signaling including: developmental, neural, neuromuscular and endocrine signaling. Receptors can be found embedded in cell membranes, cytoplasmic, nuclear and on organelles.


:(Latin, ''renes'' = kidney) Term used in relation to the kidney and associated structures (renal pelvis, renal artery)
===receptor protein tyrosine phosphatase===


:(More?[http://embryology.med.unsw.edu.au/Notes/urogen.htm  Urogenital Notes])
:(RPTP) A family of enzyme [[P#phosphatase|phosphatases]] that control aspects of nervous system development. [[P#phosphatase|Phosphatases]] remove phosphate groups from substrates, mainly proteins, and have the opposite enzymatic activity to kinases. Drosophila have 6 different RPTPs including leukocyte antigen-related (LAR) involved in photoreceptor axon targeting independent of its phosphatase activity.


===repolarization===
:(More? PMID 19889974)


:Term used in relation to the heart, repolarization is a term used to describe the relaxation after each cardiac contraction which is controlled by a gradient of ion channels.  
===receptor tyrosine kinase-like orphan receptor===
:(Ror2, Neurotrophic tyrosine kinase, receptor-related 1, NTRKR1) A cell surface receptor protein suggested to interact with [[W#wnt5a|wnt5a]] in developmental signal transduction. The receptor activates multiple downstream intracellular mediators.


:(More?[http://embryology.med.unsw.edu.au/Notes/heart.htm Heart Notes])
:(More? [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=602336 OMIM 602336])
[[File:Gray1139.jpg|thumb|150px|link=Uterus Development|alt=rectouterine pouch|rectouterine pouch]]
===rectouterine pouch===


===respiratory===
:(Pouch of Douglas or rectovaginal) Anatomical description of the female peritoneal cavity lying between the back wall of the [[U#uterus|uterus]] and rectum.


:Term used in relation to breathing (in and out) or associated with the lungs. Anatomically used to describe the lungs, air pathways and associated muscles. In cell biology used in relation to mitochondrial use of oxygen to produce energy and carbon dioxide waste.
:(More? [[Coelomic Cavity Development]] | [[Uterus Development]]
===recurrent pregnancy loss===


:(More? [http://embryology.med.unsw.edu.au/Notes/respire.htm Respiratory Notes])
:(RPL) Clinical term for 3 or more consecutive miscarriages and is suggested as due to a range of maternal and embryonic causes.


===RESOLVE===  
===reduced fetal movement===


:A national, nonprofit consumer organization offering education, advocacy, and support to those experiencing infertility. Services include a national HelpLine, quarterly newsletter, extensive literature list, member-to-member contact systems, and local support groups through a network of over 50 chapters nationwide.
:A diagnostic term for referring to an analysis of fetal movements during the third trimester. There are a wide range of different methodologies and criteria associated with this technique.


===retained products of conception===  
:(More? [[Third Trimester]] | [[Ultrasound]])
===reductive division===  


:Where part of the placenta or fetal membranes remains within the [U.htm#uterus uterus], often associated with early fetal loss in the first trimester (previously called incomplete abortion).  
:Cell division term describing meiosis where [[D#diploid|diploid]] DNA content becomes [[H#haploid|haploid]] (halved).


===rete ovarii===  
:(More? [[Cell Division - Meiosis|Meiosis]])
===reelin===


:A group of epithelial tubules located at the hilum of the ovary possibly mesonephric origin.  
:(Reln, RL) A protein required for neuronal migration and cellular layer formation during brain development. Mutation in the mouse model lead to impaired motor coordination, tremors, and ataxia. Reelin is an extracellular protein involved in signaling through the Dab1 adapter protein, and Lis1 regulate neuronal migration and cellular layer formation in the brain. The genomic structures of the mouse and human RELN genes appear to be highly conserved and the loss of Reelin and reduction in Lis1 activity in both mice and humans results in the disorganization of cortical structures.  


:(More? [http://embryology.med.unsw.edu.au/Notes/urogen.htm Urogenital Notes])
:(More? [[Neural System Development]] | [http://www.ncbi.nlm.nih.gov/omim/600514 OMIM - REELIN])


===rete testis===  
===regulatory sequence===


:The duct (epithelial tubules) conduction system for spermatazoa embedded within the mediastinum (connective tissue) located in the center of the testis (male gonad) derived from the mesonephric duct, and allow spermatazoa to travel from the seminiferous tubules to the vasa efferentia. (Spermatozoa Duct Pathway: seminiferous tubule ‚Üí straight tubule ‚Üí rete testis ‚Üí ductuli efferentes ‚Üí ductus epididymidis ‚Üí ductus deferens)
:(regulatory region, regulatory area) Genetic term describing a segment of DNA where regulatory proteins such as transcription factors can bind preferentially. The regulated gene can either increase or decrease expression following binding of these factors.


:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Spermatogenesis] | [http://embryology.med.unsw.edu.au/Notes/urogen.htm Urogenital Notes])  
:(More? [[Molecular Development]])


===retina===  
[[File:Pharyngeal_arch_cartilages.jpg|thumb|link=Head Development|alt=Reichert's cartilage|Reichert's cartilage]]
===Reichert's cartilage===  


:The stratified sensory structure of the eye, formed from the neural ectoderm that extends from the forebrain (diencephalon) to form initially the folded optic cup. Vertebrates have ten identifiable layers formed from nerve fibers, neurons, membranes, photoreceptors and pigmented cells. Light must pass through nearly all these layers to the photoreceptors. (1. Inner limiting membrane - M√ºller cell footplates; 2. Nerve fiber layer; 3. Ganglion cell layer - layer of retinal ganglion cells their axons form the nerve fiber layer and eventually the optic nerve; 4. Inner plexiform layer - another layer of neuronal processes; 5. Inner nuclear layer; 6. Outer plexiform layer; 7. Outer nuclear layer; 8. External limiting membrane - layer separating inner segment portions of photoreceptors from their cell nuclei; 9. Photoreceptor layer - rods and cones that convert light into signals; 10. Retinal pigment epithelium).  
:(second pharyngeal arch cartilage) [[N#neural crest|Neural crest]] within the second [[P#pharyngeal arch|pharyngeal arch]] forming this [[C#cartilage|cartilage]]  band. The dorsal ends form the middle ear ossicle (stapes) and temporal bone styloid process, the ventral part ossifies to form hyoid bone components of the lesser cornu and superior body. A study (PMID 16441562) suggest that this is not a continuous band (like Meckel’s) but a series of segments and mesenchymal tissue. Named after Karl Bogislaus Reichert (1811 – 1883) a German anatomist.


:(More? [http://embryology.med.unsw.edu.au/Notes/eye.htm Vision Notes])
:(More? [[Hearing_-_Middle_Ear_Development|Middle Ear]] | [[Head Development]])


===retinal pigment epithelium===  
===Reichert's membrane===


:(RPE) An epethial pigmented cell layer lying outside the sensory retina, formed from the outer layer of the folded optic cup. The RPE is firmly attached to the underlying choroid and overlying retinal visual cells, for which it has a nutritional role.
:In early rodent development, a thick multilayered basement membrane between the parietal endoderm cells and the trophoblast cells. This membrane has contentious origins, and has been suggested to begin with the formation of a basement membrane of the mural trophoblast cells, subsequent growth is from primitive endoderm cell depositions.


:(More? [http://embryology.med.unsw.edu.au/Notes/eye.htm Vision Notes])
:(More? [[Mouse Development]] | PMID 8651512)


===retinal waves===  
===relative risk===  


:A form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) along with EphA/ephrin-A signaling are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells.  
:(risk ratio or odds ratio) Term used in describing the effect of environmental [[T#teratogen|teratogens]] on development. The ratio of the rate of the condition among the exposed and the non-exposed population. (e.g. smokers risk of having a low birth weight baby compared to non-smokers) A high relative risk may indicate a low absolute risk if the condition is rare. The other risk descriptor term used to describe the likelyhood of an abnormality is [[A#absolute_risk|absolute risk]].  


:(More? [http://embryology.med.unsw.edu.au/Notes/eye.htm Vision Notes])
:(More? [[Abnormal_Development_-_Environmental|Environmental Abnormal Development]])


===Rhesus D===  
===relaxin===  


:(RhD, Rh factor) The protein on surface of red blood cells in some blood types (Rh+) and absent in others (Rh-). Can cause erythroblastosis fetalis in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy.  
:The reproductive hormone involved in [[U#uterus|uterine]] relaxation (some species), reproductive tissue growth, connective tissue remodeling (collagen), cardiovascular, renal system, and brain. Relaxin receptor is G-protein-coupled receptor (relaxin family peptide receptors 1 - 4, RXFP1-4).  


===Rh factor===
:(More? [[Genital System Development]])


:The protein on surface of red blood cells in some blood types (Rh+) and absent in others (Rh-). Can cause erythroblastosis fetalis in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy.
[[File:Fetal_10wk_urogenital_1.jpg|thumb|link=Renal System Development|alt=Early fetal kidney|Renal (=kidney)]]
===renal===


===Rho1===
:(Latin, ''renes'' = "kidney") Term used in relation to the kidney and associated structures (renal pelvis, renal artery)


:A small GTPase of the Rho subfamily (Rho, Rac and Cdc42) acts as regulatory switch for actin cytoskeleton. In development, activated in epithelial cells for invagination.
:(More? [[Renal System Development]] | [[Lecture - Renal Development]])


:(More? [http://embryology.med.unsw.edu.au/Notes/mechanism.htm Developmental Mechanisms])
===repolarization===


===rhombencephalon===
:Term used in relation to the heart, repolarization is a term used to describe the relaxation after each cardiac contraction which is controlled by a gradient of ion channels.


:(Greek ''rhombos'' = rhomboid, ''enkephalos'' = brain) The hindbrain, the most caudal neural tube primary brain vesicle (there are 3 primary brain vesicles) that will form the two secondary brain vesicles, metencephalon and the myeloncephalon. These will in turn generate in the adult brain the cerebellum, pons and medulla. The rhombencephalon lumen (cavity of the neural tube) will form the fourth ventricle.
:(More? [[Cardiovascular System Development]])


:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes] | [http://embryology.med.unsw.edu.au/Notes/neuron6.htm Ventricular System])
===Reprotox===


===rhombomere===
:A commercial online database that contains summaries on the effects of medications, chemicals, infections, and physical agents on pregnancy, reproduction, and development.


:A segmentation of the hindbrain (rhombencephalon) reflects segemental (rostro/caudal) expresion of Hox gene.
:(More? [https://reprotox.org REPROTOX] | [[Abnormal Development - Environmental]])  


:(More? [http://embryology.med.unsw.edu.au/Notes/neural.htm Neural Notes])
===respiratory===


===ricin===
:Term used in relation to breathing (in and out) or associated with the lungs. Anatomically used to describe the lungs, air pathways and associated muscles. In cell biology used in relation to mitochondrial use of oxygen to produce energy and carbon dioxide waste.


:A highly potent toxin produced by castor beans, it contains a ribotoxic A chain (RTA) and a cell-binding B chain.
:(More? [[Respiratory System Development]])


===roof plate===  
===RESOLVE===  


:Term describing the thin dorsal region of the early neural tube.  
:A national, nonprofit consumer organization offering education, advocacy, and support to those experiencing infertility. Services include a national HelpLine, quarterly newsletter, extensive literature list, member-to-member contact systems, and local support groups through a network of over 50 chapters nationwide.


:(More? [http://embryology.med.unsw.edu.au/Notes/neural.htm Neural Notes])
===resorptive bay===
[[File:Osteoclast.jpg|thumb|link=Bone_Histology|alt=Osteoclast resorptive bay|Osteoclast resorptive bay]]
:([[H#Howship's lacuna|Howship's lacuna]]) The histological name for the shallow bay or cavity lying directly under an [[O#osteoclast|osteoclast]] located at the site of bone remodeling. This microscopic extracellular matrix space represents the site of bone matrix resorption by the [[O#osteoclast|osteoclast]].


===RU 486===
:(More? [[:File:Osteoclast.jpg|Histology Image - Osteoclast]] | [[Bone Histology]] | [[Bone_Development|Bone Development Practical]] | [[Lecture - Musculoskeletal Development]])


:RU 486 (or Mifepristone) is a steroid hormone similar in structure to the natural hormone progesterone, which is used as a birth control drug.  
===respiratory embryonic stage===
[[File:Stage14_respiratory_tract.jpg|thumb|link=Respiratory System Development|alt=respiratory embryonic stage|respiratory embryonic stage]]


:(More? [http://embryology.med.unsw.edu.au/Notes/wwwhuman/MCycle/RU486.htm RU486])
:(lung bud stage) The earliest stage of lung development when the two lungs are primitive "buds" growing into the future [[P#pleural cavity|pleural cavity]].


===rubella===
::'''Lung Stages:''' [[R#respiratory embryonic stage|respiratory embryonic stage]] - [[P#pseudoglandular stage|pseudoglandular stage]] - [[C#canalicular stage|canalicular stage]] - [[T#terminal sac stage|terminal sac stage]] - [[A#alveolar stage|alveolar stage]]


:(Latin, ''rubella'' = little red) Virus also known as "german measles" (due to early citation in German medical literature). This virus can crosses the placenta from infected mothers and leads to major developmental defects in many different developing systems, including vision and hearing.
:(More?  [[Respiratory System Development]] | [[Lecture - Respiratory Development]])


:(More? [http://embryology.med.unsw.edu.au/Defect/rubella.htm Abnormal Development - Rubella Virus] | [http://embryology.med.unsw.edu.au/Defect/virus.htm Abnormal Development - Virus])
===respiratory tree===


===rugae palatinae===
:Anatomical term to describe the components of the respiratory system (lungs) as they branch again and again ending in the functional units, the [[A#alveolar sac|alveolar sacs]] ([[A#alveolus|alveolus]]).


:([P.htm#palatal_rugae palatal rugae]) The transverse ridges forming on the secondary palate which are also sequentially added as the palate grows.
:(More? [[Respiratory System Development]])


:(More? [http://embryology.med.unsw.edu.au/Notes/face.htm Face Notes] | [http://embryology.med.unsw.edu.au/Notes/face2.htm Face - Abnormalities] | [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes] | [http://www.nlm.nih.gov/medlineplus/cleftlipandpalate.html Medline Plus - Cleft Lip and Palate])
===retained products of conception===


{{Glossary}} | [http://embryology.med.unsw.edu.au/Notes/Index/S.htm Original S]
:Where part of the [[P#placenta|placenta]] or fetal membranes remains within the [[U#uterus|uterus]], often associated with early fetal loss in the [[F#first trimester|first trimester]] (previously called incomplete abortion).


===S100B===  
===rete ovarii===  


:A calcium-binding protein produced by glial cells (astrocytes, radial glia cells) with a trophic functions. :(More? [..neuron.htm Neural Notes] | [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176990 OMIM - S100B] | [http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=17362503 Hachem S, Laurenson AS, Hugnot JP, Legraverend C.] Expression of S100B during embryonic development of the mouse cerebellum. BMC Dev Biol. 2007 Mar 15;7(1):17 )
:(Latin, ''rete'' = "net", refers to a network) A group of epithelial tubules located at the hilum of the [[O#ovary|ovary]] possibly mesonephric origin.  


===sacculation===
:(More? [[Ovary Development]])


:A general anatomical term meaning to formed a series of sac-like expansions. In lung development, the term refers to the sacculprocess of lung epithelial cell differentiation, vascular remodeling and thinning of the mesenchyme. This process leads to enlargement of the diameter and surface area of the alveolar sacs. Distal epithelial cells form 2 populations: 1. cells flattens, thins, and spreads to form type I cells; 2. cells remain cuboidal, acquire surfactant filled lamellar bodies and differentiate into type II cells.
===rete ridge===


:(More? [http://embryology.med.unsw.edu.au/Notes/respire.htm Respiratory Development])
:(Latin, ''rete'' = "net", refers to a network) Integumentary histology term describing the extensions of the epidermis into the dermis. These epidermal surface thickenings extend downward between underlying connective tissue dermal papillae. This is also the site of initial eccrine gland differentiation.


===SAHF===
:(More? [[Integumentary System Development]])


:Acronym for Senescence-Associated Heterochromatic Foci, which are dense nuclear chromatin blobs found in cells undergoing senescence.
===rete testis===


===Sall4===
:(Latin, ''rete'' = "net", refers to a network) The duct (epithelial tubules) conduction system for [[S#spermatazoa|spermatazoa]] embedded within the mediastinum (connective tissue) located in the center of the testis (male gonad) derived from the mesonephric duct, and allow spermatazoa to travel from the seminiferous tubules to the vasa efferentia.


:A zinc finger transcription factor putatively involved in inner cell mass development. Nomenclature from Sal-like gene, homologus to Drosophila homeotic gene spalt (sal) which influences development of the fly's gut.
:'''Spermatozoa Duct Pathway:''' [[S#seminiferous tubule|seminiferous tubule]] - [[S#straight tubule|straight tubule]] - [[R#rete testis|rete testis]] - [[D#ductuli efferentes|ductuli efferentes]] - [[D#ductus epididymidis|ductus epididymidis]] - [[D#ductus deferens|ductus deferens]]


:(More? [http://embryology.med.unsw.edu.au/Notes/week2.htm Week 2] | [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=607343 OMIM - SALL4] | [http://flybase.bio.indiana.edu/data/allied-data/interactive-fly/gene/spalt.htm Flybase - splat] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.figgrp.1244 MBoC image - DNA binding by a zinc finger protein])
:(More? [[Lecture - Genital Development]])


===salpingitis===  
===retina===  


:Clinical term referring to an inflammation of the uterine (fallopian) tube. For example, salpingitis isthmica nodosa whcih is a nodular swelling of the isthmic segment of the uterine tube.  
:The stratified sensory structure of the eye, formed from the neural [[E#ectoderm|ectoderm]] that extends from the forebrain (diencephalon) to form initially the folded optic cup. Vertebrates have ten identifiable layers formed from nerve fibers, neurons, membranes, photoreceptors and pigmented cells. Light must pass through nearly all these layers to the photoreceptors.


:(More? [http://embryology.med.unsw.edu.au/wwwhuman/MCycle/MCycle.htm Human Menstrual Cycle] | [http://embryology.med.unsw.edu.au/Notes/genitalXXuterus.htm Genital System - Female Uterus])  
:(More? [[Vision_-_Retina_Development|Retina Development]] | [[Sensory - Vision Development]])


===SART===  
===retinal pigment epithelium===  


:Acronym for [#SART Society for Assisted Reproductive Technology].  
:(RPE) An epethial pigmented cell layer lying outside the sensory retina, formed from the outer layer of the folded optic cup. The RPE is firmly attached to the underlying choroid and overlying retinal visual cells, for which it has a nutritional role.


===Santorini’s duct===
:(More? [[Vision_-_Retina_Development|Retina Development]] | [[Sensory - Vision Development]])


:(accessory pancreatic duct, APD) A duct which may be present as an anatomical variation due to the embryological origin of the pancreas from two pancreatic buds (dorsal and ventral). Named after Giovanni Domenico Santorini (1681 - 1737) an Italian anatomist who dissecting and delineating many anatomical features. Note the main pancreatic duct (MPD) from the dorsal bud, present in the body and tail of the pancreas (also called Wirsung’s duct).
===retinal waves===


:(More? [http://embryology.med.unsw.edu.au/Notes/endocrine10.htm Pancreas] | [http://embryology.med.unsw.edu.au/Notes/endocrine10.htm#History Pancreas History])
:A form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) along with EphA/ephrin-A signaling are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells.  


===SBS===
:(More? [[Vision_-_Retina_Development|Retina Development]] | [[Sensory - Vision Development]])


:Acronym for ===S===haken ===B===aby ===S===yndrome, spectrum of neurological (eye, brain, subdural haemorrhage) and other (skeletal) injuries resulting from forcibly shaking an infant.
===retinopathy of prematurity===


:(More? [http://embryology.med.unsw.edu.au/Defect/shakenbaby.htm Abnormal Development - Shaken Baby])
:(ROP) A treatable vascular proliferative disorder that affects the incompletely vascularized retina in premature neonates, birth weight 1250 grams or less and born before 31 weeks gestation {{GA}} are at highest risk. Classified as type 2 progressing to type 1, this is a primary cause of childhood blindness. Due to retinal immaturity, neovascularization occurs leading to retinal traction and retinal detachment, eventually affecting vision.  


===SC1===
:(More? [[Sensory_-_Vision_Abnormalities|Vision Abnormalities]] | [[Birth_-_Preterm|Birth - Preterm]] | [[Sensory - Vision Development]] | [https://nei.nih.gov/health/rop/ NIH - ROP] | [http://www.aapos.org/terms/conditions/94 American Association for Pediatric Ophthalmology])


:A chemical compound which has been found to allow embryonic stem cell in vitro propagation under chemically defined conditions in the absence of feeder cells, serum, and leukemia inhibitory factor. This chemical (a heterocycle compound) inhibits Ras-GAP (Ras remains activated) then enhancing stem cell renewal through the phosphatidylinositol 3-kinase (PI3K) pathway.
===retrograde menstruation===


:(More? [http://embryology.med.unsw.edu.au/Notes/stemcell.htm Stem Cells])
:Term describing the passage of menstrual blood into the uterine tubes and peritoneal cavity during [[M#menses|menses]].


===scalp vascular plexus===
:(More? [[Menstrual Cycle]])


:A vascular feature visible on the head surface from Carnegie stage 20 (day 50).  
===Rett syndrome===
:(RTT) A severe neurodevelopment disorder, with intellectual disability and abnormalities of movement, mainly caused by mutations in the X-linked (Xq28) Methyl-CpG-binding protein 2 (MECP2) gene and therefore almost exclusively in females. The congenital variant of Rett syndrome is caused by heterozygous mutation in the FOXG1 gene on chromosome 14q13.


:(More? [http://embryology.med.unsw.edu.au/Notes/skmus8a.htm Skull Notes] | [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes])  
:(More? [[Neural System - Abnormalities]] | [[Neural System Development]] | [http://www.omim.org/entry/613454 OMIM - Congenital Rett syndrome] | [http://www.omim.org/entry/312750 OMIM - Rett syndrome])
===Rhesus D===


===scaphocephalus===
:(RhD, [[#Rh factor|Rh factor]]) See [[#Rh factor|Rh factor]] below. The protein on surface of red blood cells in some blood types (Rh+) and absent in others (Rh-). Can cause [[E#erythroblastosis fetalis|erythroblastosis fetalis]] in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy.


:One of several skull deformities (scaphocephaly, oxycephaly, plagiocephaly, trigoncephaly) caused by premature fusion (synostosis) of different developing skull sutures. Scaphocephaly results from premature sagittal suture synostosis.
===rheumatic fever===


:(More? [http://embryology.med.unsw.edu.au/Notes/skmus8a.htm Skull Notes] | [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes])
:Term for an acute disease that affects mainly children and young adults. It is a reaction to a throat infection by a particular bacteria and can damage the: heart (rheumatic heart disease, damaging muscle, valves and lining), joints and the brain.


===Schmidt-Lanterman cleft===
:(More? [[Cardiovascular System Development]])


:(Schmidt-Lanterman incisures, clefts of Schmidt-Lanterman, segments of Lanterman, medullary segments) A histological term describing the small amounts of Schwann cell cytoplasm located within the myelin sheath surrounding a myelinated neuronal axon. These spaces form channels for nutrient and other substances to be exchanged.
===rheumatoid arthritis===


:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
:A chronic inflammatory autoimmune disease in which the immune system attacks the tissues lining the joints. The inflamed joints often cause pain, heat and swelling and can lead to functional limitations and severe disability.


===schwannoma-derived growth factor===  
===Rh factor===  


:(SDGF) also called [A.htm#amphiregulin amphiregulin] (AREG), is an epidermal growth factor (EGF) family member having a role in regulating the epithelial proliferation.  
:(Rh) The protein on surface of red blood cells in some blood types (Rh+, Rh positive) and absent in others (Rh-, Rh negative). Can cause [[F#fetal_erythroblastosis|fetal erythroblastosis]] (''erythroblastosis fetalis'' or Haemolytic Disease of the Newborn) in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy. Clinical guidelines in some countries recommend anti-D immunoglobulin therapy for all pregnant women who are RhD negative, regardless of the rhesus status of the fetus. Non-Invasive Prenatal Testing (NIPT) may in future allow testing of the fetal rhesus status.


===sclerotome===  
:(More? [[Cardiovascular_System_-_Blood_Development|Blood Development]] | [[Non-Invasive Prenatal Testing]])
===Rho1===  


:The ventromedial half of each somite that forms the vertebral body and intervertebral disc.  
:A small GTPase of the Rho subfamily (Rho, Rac and Cdc42) acts as regulatory switch for actin cytoskeleton. In development, activated in epithelial cells for invagination.  


:(More? [http://embryology.med.unsw.edu.au/Notes/skmus.htm Musculoskeletal Notes] | [http://embryology.med.unsw.edu.au/Notes/week3.htm Week 3 Notes])
:(More? [[Molecular Development]])  


===SDI===  
===rhombencephalon===  


:Sexually Transmitted Infection, this term replaces the older term Sexually Transmitted Disease, any infection that can be transmitted by sex between partners. Some of these infections have been shown to impact upon embryonic and fetal development.  
:(Greek ''rhombos'' = rhomboid, ''enkephalos'' = brain, [[H#hindbrain|hindbrain]]) The hindbrain, the most caudal neural tube primary brain vesicle (there are 3 primary brain vesicles) that will form the two [[S#secondary brain vesicle|secondary brain vesicles]], the [[M#metencephalon|metencephalon]] and the [[M#myelencephalon|myelencephalon]]. These will in turn generate in the adult brain the [[C#cerebellum|cerebellum]], [[P#pons|pons]] and [[M#medulla|medulla]]. The rhombencephalon lumen (cavity of the neural tube) will form the fourth ventricle.  


:(More? [http://embryology.med.unsw.edu.au/Defect/bacteria.htm Abnormal Development - Bacterial Infection])
::'''Primary brain vesicles:''' [[P#prosencephalon|prosencephalon]] (forebrain) - [[M#mesencephalon|mesencephalon]] (midbrain) - [[R#rhombencephalon|rhombencephalon]] (hindbrain)


===second heart field===
:(More? [[Lecture - Ectoderm Development]])


:(SHF) Mesodermal region that forms adjacent to the earlier forming [[P#primary_heart_field|primary heart field]] and contribute to the rapid growth of the [[heart]] by elongating the tube and providing specific components (right ventricle and outflow tract field) of cardiac development (endocardium, myocardium, and smooth muscle). Recently suggested that this primary/secondary terminology should be replaced with gene specific expression domains or fields.  
===rhombomere===
:Hindbrain rostrocaudal segmentation established by segmental expression of Hox homeodomain transcription factors. Histologically rhombomeres are visible as undulating folds (scalloping) of the neural tube in the hindbrain region and have associated cranial nerves.


:(More? [[heart]] | [http://embryology.med.unsw.edu.au/Notes/heart.htm original Heart Notes] | [http://www.ncbi.nlm.nih.gov/pubmed/19609448 PMID: 19609448])
:(More? [[Lecture - Neural Development]] | [[Lecture - Ectoderm Development]])


===second polar body===  
===riboswitch===


:The small cytoplasmic exclusion body formed when the oocyte (egg) completes meiosis 2 at [F.htm#fertilization fertilization]. This exclusion body contains the excess DNA from the second reductive division (the first was formed from meiosis 1 at ovulation, and the third polar body is from division of this first body). 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 [F.htm#fertilization fertilization].  
:A type of molecular regulation in bacteria where an RNA element binds metabolites and then regulates gene expression. This type of regulation is usually [[C#cis|cis]], where a 5' untranslated region (5'UTR) riboswitch modulates transcription or translation of the downstream coding sequence.


:(More? [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes])
===rich club===


===second trimester===
:A new neural pathway term that refers to brain regions that form a high-cost, high-capacity backbone thought to enable efficient network communication. This has been shown to differ in pre-term infants.


: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? [[Neural System Development]] | [[Birth_-_Preterm#Neural_Development|Preterm]] | PMID 24799693)


:(More? [http://embryology.med.unsw.edu.au/wwwhuman/Stages/Stages.htm Embryo Stages] | [http://embryology.med.unsw.edu.au/wwwhuman/fetus.htm Human Fetal Period] | [http://embryology.med.unsw.edu.au/week/weekbyweek.htm Development Week by Week])
===ricin===


===securin===
:A highly potent toxin produced by castor beans, it contains a ribotoxic A chain (RTA) and a cell-binding B chain.


:An inhibitory chaperone protein important cell division. Destruction of this protein leads to activation of separase. which then allows separation of sister chromatids (chromosomes) at mitosis metaphase-to-anaphase transition.
===RNA retrovirus===


:(More? [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes])
:A virus with genetic material stored in the form of RNA that can replicate in a host cell and then by reverse transcriptase produce DNA that is then incorporated into the host's genome.


===segmentation===
:(More? [[Abnormal Development - Viral Infection]])


:Term used to describe the process of breaking a solid structure into a number of usually equal size pieces.
===RNA silencing===


===seizure===
:(RNA interference, RNAi, microRNA, miRNA) Molecular development term describing the complex of mechanisms that regulate gene expression through small RNA molecules, in mammals this is mainly the microRNA (miRNA) pathway. These short RNA molecules, produced by RNAse III family enzyme Dicer, guide sequence-specific silencing of gene expression to suppress mRNA translation into protein. This mechanism has also been identified in early development during week 1 in [[Z#zygote|zygote]] to [[B#blastocyst|blastocyst]] formation.


:(Latin, ''sacire'' = to take possession of) A clinical condition associated with discharge (abnormal, excessive, hypersynchronous) of a group of cortical neurons. Recurrent seizures of unknown etiology occur in Epilepsy.


:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
:(More? [[Molecular Development]])


===sella turcica===  
===Robinow syndrome===


:(Latin ''sella'' = saddle, ''turcica'' = Turkish) refers to the shape of the sphenoid bone in which the pituitary gland resides (pituitary fossa). :(More? [http://embryology.med.unsw.edu.au/Notes/endocrine7.htm Endocrine Notes - Pituitary])
:A skeletal dysplasia characterized by short stature, limb shortening, genital hypoplasia, and craniofacial abnormalities. Has both autosomal dominant and autosomal recessive (original family described by Meinhard Robinow) inheritance patterns. Recently, two different missense mutations in [[W#Wnt5a|Wnt5a]] have been identified with the autosomal dominant Robinow syndrome, resulting in decreased [[W#Wnt5a|Wnt5a]] activity.


===senescence===
:(More? [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=268310 OMIM 268310])


:In aging, generally at a cellular level with the accumulation of various ageing effects. Cells no longer carrying out their differentiated function and begine to decline. In many cases cells can divide a limited number of times before they become senescent, while oncogenic (cancer) cells can "escape" senescence and become proliferative.
===Robson classification===


===sensitivity===
:(10 group classification) A clinical term for a caesarean delivery classification system first described by Robson in 2001.


:See [P.htm#prenatal_screening_sensitivity prenatal screening sensitivity]  
:(More? [[Birth_-_Caesarean_Delivery#Caesarean_Classification|Caesarean Classification]] | {{Caesarean}} | [https://www.ncbi.nlm.nih.gov/pubmed/11359322 PMID 11359322])


===separase===  
===roof plate===  


:An important cell division protease allows the separation of sister chromatids (chromosomes) at mitosis metaphase-to-anaphase transition. This enzyme is activated by destruction of an inhibitory chaperone (securin).  
:The term used to describe the thin dorsal region of the early [[N#neural tube|neural tube]] forming the central nervous system (brain and spinal cord). The roof plate also lies adjacent to the dorsal [[E#ectoderm|ectoderm]] and initial [[N#neural crest|neural crest]] prior to migration. The opposite side of the early neural tube forms the  [[F#floor plate|floor plate]] and the lateral parts are divided into two thicker regions, the [[A#alar plate|alar plate]] and [[B#basal plate|basal plate]].


:(More? [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes])
:(More? [[Lecture - Ectoderm Development]] | [[Neural System Development]])


===septicemia===  
===Ror2===
:An acronym for [[R#receptor tyrosine kinase-like orphan receptor|receptor tyrosine kinase-like orphan receptor]].


:Bacteria present in the blood lead to an amplified and dysregulated immune response. Common infection sites for bacterial entry into the blood are infections in: lungs, urinary tract, abdominal cavity, and primary infections of the bloodstream.
:(More? [[Molecular Development]]
===rostral neuropore===
:([[R#cranial neuropore|cranial]], [[C#cephalic neuropore|cephalic]] or [[A#anterior neuropore|anterior]]) See [[R#cranial neuropore|cranial neuropore]].


:(More? [http://embryology.med.unsw.edu.au/Notes/heart.htm Circulatory Notes] | [http://embryology.med.unsw.edu.au/Notes/placenta.htm Placenta Notes])  
:(More? [[Neural System Development]])


===septum transversum===  
===rostrocaudal===


:(transverse septum) A mesodermal region in the early embryo. Identified externally as the junctional site between amnion and yolk sacs, and internally (within the embryo) lying directly beneath the heart and at the foregut/midgut junction. This ventro-dorsal "plate" of mesoderm contributes several structures including: the central tendon of diaphragm and some of the liver. The transverse septum has an important structural role in early embryonic development and is pierced by the gastrointestinal tract.
:Anatomical axis term used to describe a head (rostral) to tail (caudal) direction or sequence of developmental events. Some embryonic structures form initially in a rostral (head-ward) region and later similar structures form more caudal (tail-ward). Examples include somite formation ([[S#somitogenesis|somitogenesis]]), [[L#limb|limb]] and [[P#pharyngeal arch|pharyngeal arch]] development.


:(More? [http://embryology.med.unsw.edu.au/Notes/git.htm Gastrointestinal Tract Notes] | [http://embryology.med.unsw.edu.au/Notes/git7.htm Liver Notes] | [http://embryology.med.unsw.edu.au/Notes/respire7.htm Respiratory Development - Diaphragm])  
===rotavirus===
[[File:Rotavirus.jpg|thumb|alt=Rotavirus|Rotavirus]]
:A type of virus that is a common cause of diarrhoea and vomiting in infants and young children. The live attenuated rotavirus vaccine is contraindicated in pregnancy, but can be safely administered to household contacts of pregnant women. There is only a very small risk of transmission of the rotavirus vaccine virus to a susceptible pregnant woman and there is no evidence of risk to the fetus if pregnant women are in contact with recently vaccinated individuals. (data based on: The Australian Immunisation Handbook 9th Edition 2008 [http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-specialrisk232#t231 2.3.2 Vaccination of women planning pregnancy, pregnant or breastfeeding women, and preterm infants - updated July 2009] )


===Sertoli cells===
:(More? [[Abnormal Development - Viral Infection|Viral Infection]] | [http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-specialrisk232#t231 2.3.2 Vaccination of women planning pregnancy, pregnant or breastfeeding women, and preterm infants - updated July 2009] | [http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-home  The Australian Immunisation Handbook 9th Edition 2008])


:The supporting cells in the testes (male gonad) that induce primordial germ cells to commit to sperm development. Support is nutritional and mechanical, as well as forming a blood-testis barrier. In development these cells secrete anti-Müllerian hormone, which causes the Müllerian (paramesonephric) duct to regress, and help to induce other somatic cells to differentiate into Leydig cells. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
===RU 486===


:(More? [http://embryology.med.unsw.edu.au/Notes/urogen.htm Urogenital Notes] | [http://www.whonamedit.com/doctor.cfm/556.html Enrico Sertoli] | [http://www.lab.anhb.uwa.edu.au/mb140/CorePages/MaleRepro/malerepro.htm UWA Blue Histology - Male Reproductive System])
:([[M#mifepristone|mifepristone]]) Clinical potent hormone progesterone and glucocorticoid receptor antagonist used as a birth control drug. Progesterone binding to the progesterone receptor generates a receptor conformational change allowing it to bind to DNA and act as a transcription factor for genes. RU486 binds with 10-fold higher affinity the same receptor C-terminal region of the hormone-binding domain and then does not act as a transcription factor.


===Sessel's pouch===
:(More? [[Mifepristone]])


:In early head development, an endodermal bud underlying the nasofrontal bud will form Sessel's pouch which later degenerates. In the chick embryo, this structure patterns first the nasal septum and later the nasal capsule, the ethmoid bone, and the upper beak.  
===rubella===
[[File:Infant rubella virus.jpg|thumb|alt=Infant rubella virus|Infant rubella virus]]
:(Latin, ''rubella'' = little red) Virus also known as "german measles" (due to early citation in German medical literature). This virus can crosses the [[P#placenta|placenta]] from infected mothers and leads to major developmental defects in many different developing systems, including vision and hearing.


===SET===
:(More? [[Abnormal_Development_-_Rubella_Virus|Abnormal Development - Rubella Virus]])


:Acronym for '''S'''ingle-'''E'''mbryo '''T'''ransfers, a single embryos transferred when women undergo Assisted Reproduction Technology compared to double-embryo transfer (DET).  
===rugae palatinae===
[[File:Mouse_ruga_pattern.jpg|thumb|alt=Mouse palatal rugae|Mouse palatal rugae]]
:([[P#palatal_rugae|palatal rugae]]) The transverse ridges forming on the secondary palate which are also sequentially added as the palate grows.  


:(More? [http://embryology.med.unsw.edu.au/Notes/week1_5b.htm In Vitro Fertilization])  
:(More? [[Palate Development]] | [[Abnormal_Development_-_Cleft_Palate|Cleft Palate]] | [[Abnormal_Development_-_Cleft_Lip_and_Palate| Cleft Lip and Palate]] | [[Head Development]])


===sflt-1===  
===Runx1===


:acronym for soluble vascular endothelial growth factor (VEGF) receptor-1 also known as sVEGFR-1. A soluble receptor which has been shown to trap VEGF-A stopping it from stimulating the formation of blood vessels in the cornea.  
:(Acute Myeloid Leukemia 1, AML1) Transcription factor of the Runt-related protein family (3 members in the mammalian family). Runx1 can act as a context-dependent transcriptional activator or repressor. In neural development, expressed in post-mitotic neurons and plays important roles in both phenotype specification and axonal targeting. AML1 is one of the most frequent targets of chromosome translocations associated with leukemia.


:(More? [http://embryology.med.unsw.edu.au/Notes/eye.htm Eye Notes] | [http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=17051153&dopt=Abstract Ambati BK, etal.] Corneal avascularity is due to soluble VEGF receptor-1. Nature. 2006 Oct 18)  
:(More? [[Neural System Development]] | [[Molecular Development]] | [http://www.ncbi.nlm.nih.gov/omim/151385 OMIM - Runx1])


===SHFM===


:An acronym for [#split_hand_foot_malformation  Split Hand Foot Malformation]


===SIRT===
{{Glossary comment}}


:A mammalian homologue of Sir2 (Silent information regulator 2) a NAD-dependent deacetylase that links metabolism with longevity in several species. Mammals have 7 homologues (SIRT1–7) which together potentially regulate several functions associated with physiology, calorie restriction, and aging.


===shotgun sequencing===
{{Glossary}}
 
:DNA sequencing method. Breaks chromosomal DNA into small overlapping fragments which are individually sequenced, the entire sequence is then "reconstructed" by linking overlapped sequences together. This method has been used for whole genome sequencing.
 
:(More? [http://embryology.med.unsw.edu.au/MolDev/page1.htm Molecular Notes])
 
===single letter amino acid code===
 
:The individual amino acids that form proteins can be represented by a standardised single letter code, three letter code or by their entire name.
 
===A=== - Alanine (Ala) | ===C=== - Cysteine (Cys) | ===D=== - Aspartic Acid (Asp) | ===E=== - Glutamic Acid (Glu) | ===F=== - Phenylalanine (Phe) | ===G=== - Glycine (Gly) | ===H=== - Histidine (His) | ===I=== - Isoleucine (Ile) | ===K=== - Lysine (Lys) |===L=== - Leucine (Leu) | ===M=== - Methionine (Met) | ===N=== - Asparagine (Asn) | ===P=== - Proline (Pro) | ===Q=== - Glutamine (Gln) | ===R=== - Arginine (Arg) | ===S=== - Serine (Ser) | ===T=== - Threonine (Thr) | ===V=== - Valine (Val) | ===W=== - Tryptophan (Trp) | ===Y=== - Tyrosine (Tyr)
 
:(More? [http://embryology.med.unsw.edu.au/MolDev/page1.htm Molecular Notes])
 
===single umbilical artery===
 
:(SUA) Placental cord with only a single placental artery (normally paired). This abnormality can be detected by ultrasound (colour flow imaging of the fetal pelvis) and is used as an indicator for further prenatal diagnostic testing for chromosomal abnormalities and other systemic defects.
 
:(More? [http://embryology.med.unsw.edu.au/Defect/page7.htm Prenatal Diagnosis] | [http://embryology.med.unsw.edu.au/Movies/ultrasound.htm Ultrasound] | [http://embryology.med.unsw.edu.au/Defect/page21.htm Trisomy 21])
 
===sinoatrial node===
 
:Heart region consisting of modified/specialized myocardial cells that initiate the heart beat. This cardiac pacemaker region lies at the junction of the right atrium and the superior vena cava (superior caval vein) and is initially formed from embryonic myocardial cells bordering the inflow tract of the early heart tube.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/heart.htm Heart Notes] | [http://embryology.med.unsw.edu.au/Notes/heart8.htm Embryonic Heart Rate])
 
===sinus venosus===
 
:early developmental cardiovascular structure, thin walled cavity, forming the input to developing heart which has 3 venous inputs (vitelline vein, umbilical vein, commom cardinal vein). Later in heart development this structure gets incorporated into the wall of the future right atrium. Abnormalities of sinus venosus development contribute about 10% of all atrial septal defects.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/heart.htm Heart Notes] | [http://embryology.med.unsw.edu.au/Notes/heart2.htm#asd.htm Heart Abnormalities - ASD])
 
===siRNA===
 
:acronym for small interfering RNAs, a class of regulators of gene expression. They are generated from double-stranded RNA (dsRNA) precursors. There is also another class of small RNAs involved in gene expression present in cells, MicroRNA, based upon "Dicer".
 
===Sizzled===
 
:(Szl) a member of the secreted Frizzled receptor related protein (Sfrp) family identified in chicken. These proteins are antagonists and modifiers of Wnt and BMP signalling and is expressed in early heart development.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/heart.htm Heart Notes])
 
===SMAD4===
 
:A gene homologue 4 of Mothers Against Decapentaplegic (drosophila gene), tumor suppressor gene, its mutation causes 90% of human pancreatic carcinomas (pancreatic ductal adenocarcinomas). Deletion of SMAD4 in embryonic pancreatic epithelium had no apparent effect on pancreatic development.
 
:(More? [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=600993 OMIM - SMAD4] | [http://embryology.med.unsw.edu.au/Notes/endocrine10.htm Endocrine Development - Pancreas] | [http://www.genesdev.org/cgi/content/abstract/20/22/3130 Article - knockout SMAD4])
 
===small intestine===
 
:The gastrointestinal tract between stomach and large intestine, functions include digestion and absorption of nutrients. The small intestine is then subdivided into 3 regions: duodenum, jejunum and ileum.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/git.htm GIT Notes])
 
===Snail===
 
:The zinc finger transcriptional repressors involved in regulation of epithelial–mesenchymal transitions in vertebrates.
 
:(More? [http://embryology.med.unsw.edu.au/MolDev/factor/snail.htm Molecular Factors- Snail])
 
===single-nucleotide polymorphism===
 
:(SNP) places in the genome sequence where one fraction of the human population has one nucleotide, while another fraction has another. SNPs are the most abundant form of DNA variation in the human genome with an estimated 7 million common SNPs with a minor allele frequency (MAF) of at least 5% across the entire human population. Most SNPs have no effect on phenotype, though a subset of SNPs are the genetic basis of human variability. Reference: DA Hinds etal., [http://www.sciencemag.org/cgi/content/full/307/5712/1072 Whole-Genome Patterns of Common DNA Variation in Three Human Populations]
 
===SNP===
 
:Acronym for [#snp single-nucleotide polymorphism]
 
===Society for Assisted Reproductive Technology===
 
:(SART) An affiliate of the American Society for Reproductive Medicine composed of clinics and programs that provide ART (Assisted Reproductive Technology). SART reports annual fertility clinic data to the Centers for Disease Control and Prevention (CDC). [http://sart.org/home.html SART Website]
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_5b.htm Week 1 Notes - IVF])
 
===soft palate===
 
:(velum, muscular palate) The muscular posterior portion of the palate forming the roof of the oral cavity. The bony anterior portion of the palate is called the hard palate, formed by maxillary and palatine bones.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes])
 
===somatic mesoderm===
 
:Mesoderm derived from lateral plate mesoderm, and found closest to the ectoderm and separated from other component of lateral mesoderm (splanchnic, near endoderm) by the intraembryonic coelom. Note: Students often confuse the terms, and therefore the derivatives of, somatic mesoderm with "somitic mesoderm" (which is the somite).
 
===soma===
 
:(Greek, ''soma'' = body) Term used to describe tne cell body of a neuron. Also used in relation to body structures (somatic, somatosensory).
 
===somesthetic===
 
:(Greek, ''soma'' = body) = somatosensory, sense perception.
 
===somite===
 
:Segmental block (ball) of mesoderm formed from paraxial mesoderm adjacent to notochord (axial mesoderm) forming muscle and connective tissues of the body. Differentiates to form two intermediate components called the [[S#sclerotome|sclerotome]] and [[D#dermamyotome|dermamyotome]] (then [[D#dermatome|dermatome]] and [[M#myotome|myotome]]). Note the paraxial mesoderm of the head region does not segment.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/skmus.htm Musculoskeletal Notes] | [http://embryology.med.unsw.edu.au/Notes/week3.htm Week 3 Notes])
 
===somitocoel===
 
:A transient cavity that appears within each of the early forming somites which is then lost as cells proliferate within the [#somite somite].
 
:(More? [http://embryology.med.unsw.edu.au/Notes/skmus.htm Musculoskeletal Notes] | [http://embryology.med.unsw.edu.au/Notes/week3.htm Week 3 Notes])
 
===somitogenesis===
 
:The process of segmentation of the paraxial mesoderm within the trilaminar embryo body to form pairs of somites, or balls of mesoderm. A somite is added either side of the notochord (axial mesoderm) to form a somite pair. The segmentation does not occur in the head region, and begins cranially (head end) and extends caudally (tailward) adding a somite pair at regular time intervals. The process is sequential and therefore used to stage the age of many different species embryos based upon the number visible somite pairs. In humans, the first somite pair appears at day 20 and adds caudally at 1 somite pair/90 minutes until on average 44 pairs eventually form.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week3_6.htm Week 3 - Somitogenesis] | [http://embryology.med.unsw.edu.au/Notes/skmus.htm Musculoskeletal Notes])
 
===sonic hedgehog===
 
:(SHH) secreted growth factor that binds patched (ptc) receptor on cell membrane. SHH function is different for different tissues in the embryo. In the ===nervous system===, SHH is secreted by the notochord, ventralizes the neural tube, inducing the floor plate and motor neurons. In the ===limb===, SHH is secreted by the zone of polarizing activity (ZPA) organizing limb axis formation. SHH has still others roles in ===organ development=== in lung, pancreas, etc. SHH name derives from homology to the original fruitfly (drosophila) "hedgehog" mutation, where these flies have hairs in regions (ventral) which are normally hair-free, and therefore have a disrupted body pattern. Nomenclature note lower case shh for other species, upper case SHH in humans.
 
:(More? [http://embryology.med.unsw.edu.au/MolDev/factor/shh.htm Molecular Factors - sonic hedgehog] | [http://embryology.med.unsw.edu.au/MolDev/MolDev.htm Molecular Notes] | [http://embryology.med.unsw.edu.au/Notes/skmus.htm Musculoskeletal Notes] | [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===SOX2===
 
:Acronym for ===S===ry-related HMG-B===ox ===2, a 317-amino acid protein involved in regulating many different systems.
 
:(More? OMIM [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=184429 Sox2])
 
===SOX9===
 
:Gene and protein name for SRY-related high-mobility group (HMG) box 9, a 509-amino acid transcription factor protein involved in regulating many different systems, including mammalian testis determination and pancreas organogenesis (a progenitor cell specific marker and maintenance factor). See also Sry.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/endocrine10.htm Pancreas Notes] | [http://embryology.med.unsw.edu.au/MolDev/MolDev.htm Molecular Notes] | OMIM [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=608160 Sox9] | Protein [http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&val=758103 Sox9] | PNAS [http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=17267606 Seymour PA, Freude KK, Tran MN, Mayes EE, Jensen J, Kist R, Scherer G, Sander M.] SOX9 is required for maintenance of the pancreatic progenitor cell pool. Proc Natl Acad Sci U S A. 2007 Jan 31)
 
===spalt===
 
:Drosophila homeotic zinc finger transcription factor gene (sal) which influences development of the fly's gut. Human homologue are SALL (sal-like) genes.
 
:(More? [http://flybase.bio.indiana.edu/data/allied-data/interactive-fly/gene/spalt.htm Flybase - splat] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.figgrp.1244 MBoC image - DNA binding by a zinc finger protein])
 
===sperm===
 
:The male haploid reproductive cell, often used generically (and incorrectly) to describe these cells and the fluid of the ejaculate. Term is a shortened form of scientifically correct term [#spermatazoa spermatazoa].
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spermatazoa===
 
:The male haploid reproductive cell, produced by meiosis in the testis (male gonad).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spermatogenesis===
 
:(Greek, ''genesis'' = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called [#spermiogenesis spermiogenesis].
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spermiogenesis===
 
:(Greek, ''genesis'' = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm shape and organization. This process involves reorganization of cellular organelles (endoplasmic reticulum, golgi apparatus, mitochondria), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spermatogonia===
 
:The cells located in the seminiferous tubule adjacent to the basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spermatogonial stem cells===
 
:The spermatagonia cells located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Week 1 - Spermatogenesis])
 
===spina bifida===
 
:( ''spina bifida'' = "split spine") A neural tube defect (NTD) caused by failure of the early neural tube to close correctly. This defect can occur anywhere along the length of the neural tube at the level of the spinal cord. The defect can also occur at the spinal cord end of the neural tube, the posterior neuropore. Because the neural tube remains open in adddition to the neural effects, the surrounding spinal column/vertebra, connective tissue and skin may also be affected. The two main forms are ===open=== (neural elements are exposed to the external environment) or ===closed=== (occult, covered with skin).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron2.htm Neural Abnormalities] | [http://embryology.med.unsw.edu.au/Defect/page5e.htm Neural Tube Defects])
 
===spinal canal===
 
:The mature space in the core of the spinal cord (filled with CSF) formed from the original lumen of the neural tube. :(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===spinal cord===
 
:The caudal (tail) end of neural tube that, together with the brain (rostral end of neural tube), forms the central nervous system (CNS). Note: the process of secondary neuralation contributes the very caudal end of the spinal cord.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===spinal dysraphism===
 
:(neural tube defects, NTD) abnormality resulting from a developmental incomplete closure of the neural tube leading to not only neural but also spinal column defects. The two main forms are open (neural elements are exposed to the external environment) or closed (occult, covered with skin).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===spinal ganglia===
 
:(dorsal root ganglia, DRG) Aperipheral nervous system 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? [http://embryology.med.unsw.edu.au/Notes/ncrest.htm Neural Crest Notes])
 
===spinal nerve===
 
:A mixed nerve (motor and sensory) arising as lateral pairs at each vertebral segmental level.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===splanchnic mesoderm===
 
:Gastrointestinal tract (endoderm) associated mesoderm formed by the separation of the lateral plate mesoderm into two separate components by a cavity, the intraembryonic coelom. Splanchnic mesoderm is the embryonic origin of the gastrointestinal tract connective tissue, smooth muscle, blood vessels and contribute to organ development (pancreas, spleen, liver). The intraembryonic coelom will form the three major body cavities including the space surrounding the gut, the peritoneal cavity. The other half of the lateral plate mesoderm (somatic mesoderm) is associated with the ectoderm of the body wall.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week3.htm Week 3] | [http://embryology.med.unsw.edu.au/Notes/git.htm Gastrointestinal Tract Notes] | [http://embryology.med.unsw.edu.au/Notes/heart.htm Heart Notes] )
 
===spleen===
 
:The spleen develops within the gastrointestinal tract dorsal mesogastrium mesenchyme. With folding it is located on the left side of the abdomen and has a role initially in blood (haematopoisis, blood cell formation) and later immune system development. The spleen's haematopoietic function is lost with fetal development and lymphoid precursor cells migrate into the developing organ.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/git8.htm Spleen Notes] | [http://embryology.med.unsw.edu.au/Notes/git.htm Gastrointestinal Tract Notes])
 
===spontaneous abortion ===
 
(miscarriage) A pregnancy ending in the spontaneous loss of the embryo or fetus before 20 weeks of gestation.
 
===spliceosome===
 
:The structure formed within the cell nucleus a complex assembly of proteins and RNA required for processing RNA, removing introns to generate the exon only mRNA sequence. The complex is formed from five small nuclear ribonucleoprotein particles (snRNPs) and more than 300 different proteins.
 
===split hand foot malformation===
 
:(SHFM, ectrodactyly, cleft hand, central ray deficiency) highly variable malformation (genetic heterogeneous, 5+ loci mapped) of hand and foot abnormalities occuring in isolation or in association with other systematic anomalies (congenital heart defects).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/skmus72.htm Musculoskeletal - Limb Development Abnormalities])
 
===spontaneous abortion ===
 
(miscarriage) a pregnancy ending in the spontaneous loss of the embryo or fetus before 20 weeks of gestation.
 
===SPS===
 
:(Serine, Proline, Serine) A protein general nuclear translocation signal (NTS) sequence. SPS is the single amino acid code for a 3 amino acid domain that when phosphorylated binds to importin7 and gets released from nuclear pore proteins.
 
:(More? [http://www.molecule.org/content/article/abstract?uid=PIIS1097276508005431 Molecular Cell, Vol 31, 850-861, 26 September 2008])
 
===sry===
 
:(Sry, human; Testis-Determining Factor, TDF; Testis-Determining Factor on Y, TDY ) Gene name ===s===ex-determining ===r===egion of ===Y===, the gene locus on the Y chromosome encoding the male "testis determining factor", a protein transcription factor and a member of the high mobility group (HMG)-box family of DNA binding proteins. See also the transcription factor SRY-related protein, SOX9 (SRY-related high-mobility group (HMG) box 9)
 
:(More? [http://embryology.med.unsw.edu.au/MolDev/MolDev.htm Molecular Notes] | [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes] | [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=480000 OMIM])
 
===SSRI===
 
:Acronym for ===S===elective ===S===erotonin ===R===euptake ===I===nhibitors, drugs used in the treatment of depression, antidepressants. Some examples include: citalopram (brand name of Celexa), fluoxetine (brand name of Prozac), paroxetine (brand name of Paxil) and sertraline (brand name of Zoloft).
 
:(More? [http://embryology.med.unsw.edu.au/Defect/drugs.htm Abnormal Development - Maternal Drugs] | [http://www.healthinsite.gov.au/topics/Selective_Serotonin_Reuptake_Inhibitors Australia healthinsite - SSRIs])
 
===Stage-Specific Embryonic Antigen-1===
 
:(SSEA-1) A cell surface embryonic marker (antigen) which has a role in cell adhesion, migration and differentiation and is often differentially expressed during stem cell development. Can be identified by Davor Solter monoclonal antibody MC-480 (SSEA-1).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/stemcell4.htm Stem Cell Notes])
 
===Stage-Specific Embryonic Antigen 4===
 
:(SSEA-4) A cell surface embryonic marker (antigen) of human teratocarcinoma stem cells (EC), human embryonic germ cells (EG) and human embryonic stem cells (ES) which is down-regulated following differentiation of human EC cells. This antigen is not expressed on undifferentiated murine EC, ES and EG cells but upregulated on differentiation of murine EC and ES cells. Can be identified by Davor Solter monoclonal antibody MC-813-70 (SSEA-4).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/stemcell4.htm Stem Cell Notes])
 
===stem cell===
 
:Term used to describe a cell with the potential to reproduce itself indefinitely, as well as differentiate into any other embryo tissue cell types. There are also a number of different specialised stem cell definitions: totipotential stem cell (as described above), pluripotential stem cell (capable of forming a number of different cell types), embryonic stem cell (derived from the blastocyst), cord blood stem cell (derived from placental cord blood), and adult stem cell (derived from adult or postnatal tissue).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/stemcell.htm Stem Cell Notes])
 
===Stem Cell Antigen 1===
 
:(Sca-1) A cell surface marker (antigen) for mouse hematopoietic progenitor/stem cell subset. It is a member of the Ly-6 family of GPI-linked surface proteins (Mr 18 kDa).
 
:(More? [http://embryology.med.unsw.edu.au/Notes/stemcell.htm Stem Cell Notes])
 
===stenosis===
 
:Term used to describe an abnormal narrowing, usually in relation to a tube. For example, blood vessel, gastrointestinal tract or respiratory tract.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/git2.htm Gastrointestinal Tract Abnormalities])
 
===stillbirth===
 
:A fetus or infant delivered without signs of life after 20 weeks or more of gestation.
 
===stigmergy===
 
:term, named by Pierre-Paul Grasse studying ants and termites, used to describe a self-organising system arising from individuals interacting with their environment. This mechanism is suggested to have a role in the developing neural system, responding to a series of attractive and repulsive extracellular cues.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
 
===stimulated cycle===
 
:An ART cycle in which a woman receives drugs to stimulate her ovaries to produce more follicles.
 
:(More? [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes])


===stomach===


:Gastrointestinal tract (GIT) foregut organ that has a major function in digestion. In humans, during week 4 initially as a dilatation of the foregut lying behind the heart. Differential growth of the ventral and dorsal walls establishes the greater curvature of the stomach and second rotation (of 90 degrees) occurs on the longitudinal axis establishing the adult anatomical orientation of the stomach.


:(More? [http://embryology.med.unsw.edu.au/Notes/git10.htm Gastrointestinal Tract - Stomach] | [http://embryology.med.unsw.edu.au/Notes/git.htm Gastrointestinal Tract Notes])
===stomadeum===
:(stomadeum) A ventral surface depression on the early embryo head surrounding the [B.htm#buccopharyngeal_membrane buccopharyngeal membrane], which lies at the floor of this depression. This surface depression lies between the maxillary and mandibular components of the first pharyngeal arch.
:(More? [http://embryology.med.unsw.edu.au/Notes/git.htm Gastrointestinal Tract Notes] | [http://embryology.med.unsw.edu.au/Notes/head.htm Head Notes])
===straight tubule===
:(tubulus rectus) A structure within the testis (male gonad) a tubular system connecting seminiferous tubule to the rete testis within the mediastinum. (Spermatozoa Duct Pathway: seminiferous tubule ‚Üí straight tubule ‚Üí rete testis ‚Üí ductuli efferentes ‚Üí ductus epididymidis ‚Üí ductus deferens)
:(More? [http://embryology.med.unsw.edu.au/Notes/week1_3b.htm Spermatogenesis])
===stroma===
:(Greek, ''stroma'' = "a cover, table-cloth, bedding") Histological term used to describe supportive cells within an organ, tissue or structure. The term is often paired with [P.htm#parenchyma parenchyma], which describes the functional cells of an organ, tissue or structure. All organs can therefore be functionally divided into these 2 components, stromal/parenchymal.
===stromal cells===
:(Greek, ''stroma'' = "a cover, table-cloth, bedding") Descriptive term in the ovary, for cells surrounding the developing follicle that form a connective tissue sheath (theca folliculi). This layer then differentiates into 2 layers (theca interna, theca externa). This region is vascularized and involved in hormone secretion.
:(More? [http://embryology.med.unsw.edu.au/Notes/week1.htm Week 1 Notes])
===subcapsular sinus===
:(marginal sinus) space lying under the connective tissue capsule which receives lymph from afferent lymphatic vessels.
:(More? [http://embryology.med.unsw.edu.au/Notes/heart31.htm Cardiovascular System Development - Lymphatics])
===subventricular zone===
:(SVZ) A region/layer in the developing nervous system near the ventricular layer from which newly formed neuroblasts migrate. Also the site of adult neurogenesis (neural stem cells) in the anterior lateral ventricles.
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
===sulcation===
:The process of brain growth in the second to third trimester which forms sulci, grooves or folds visible on fetal brain surface as gyri grow (gyration). Abnormalities of these processes can lead to a smooth brain (lissencephaly).
:(More? [http://embryology.med.unsw.edu.au/Notes/neuron.htm Neural Notes])
===SUMO===
:An acronymn for '''S'''mall '''U'''biquitin-like '''Mo'''difier protein, which are a family of small proteins that modify the function of other proteins by covalently attaching to and detaching from the other proteins.
:(More? [http://embryology.med.unsw.edu.au/Notes/placenta11.htm Placental Molecular])
===SUMOylation===
:A post-translational protein modification involving SUMO proteins attaching/detaching to other proteins and has a role in many different cellular processes. Similar to the degradation ubiquitination process.
:(More? [http://embryology.med.unsw.edu.au/Notes/placenta11.htm Placental Molecular])
===surfactant===
:A detergent secreted by Type 2 alveolar cells between alveolar epithelium. Functions to lower surface tension, allowing lungs to remain inflated. Note: In humans, these cells and their secretion develop towards the very end of the third trimester, just before birth. Hence the respiratory difficulties associated with premature births (Newborn Respiratory Distress Syndrome, Hyaline membrane disease).
:(More? [http://embryology.med.unsw.edu.au/Notes/respire.htm Respiratory Notes] | [http://embryology.med.unsw.edu.au/Notes/respire2.htm Respiratory Abnormalities] | [http://embryology.med.unsw.edu.au/Notes/respire2.htm#hyaline+membrane Newborn Respiratory Distress Syndrome])
===SWISH===
:Acronym for '''S'''tate '''W'''ide '''I'''nfant '''S'''creening '''H'''earing program. A newborn hearing testing program using an automated auditory response technology. Program was introduced in NSW Australia in 2002 across 17 area health service coordinators.
:(More? [http://embryology.med.unsw.edu.au/Notes/ear.htm Hearing Notes] | [http://embryology.med.unsw.edu.au/Notes/ear2.htm Hearing Abnormalities] | [http://embryology.med.unsw.edu.au/Notes/Child/neonatalscreening.htm Child Notes - Neonatal Screening] | [http://embryology.med.unsw.edu.au/Notes/Child/neonatalscreening.htm#Hearing Child Notes - Neonatal Hearing Screening])
===syncytialization===
:The process of cellular fusion to form a multinucleated cytoplasmic mass, occurs in placenta ([#syncytiotrophoblast syncytiotrophoblast]) and skeletal muscle (myoblast to myotube) development. The process involves cellular recognition, migration, adhesion and finally cell fusion between the two interacting cells.
:(More? [http://embryology.med.unsw.edu.au/Notes/week2.htm Week 2 Notes] | [http://embryology.med.unsw.edu.au/Notes/placenta.htm Placenta Notes] | [http://embryology.med.unsw.edu.au/Notes/skmus12.htm Musculoskeletal Development - Muscle Development])
===syncytiotrophoblast===
:A multinucleated cell currently thought to form by the fusion of cytotrophoblasts (trophoblasts) within the trophoblast layer (shell) of the implanting conceptus. In early development, these cells mediate implantation of the conceptus into the uterine wall and secrete the hormone ([C.htm#human_chorionic_gonadotrophin human Chorionic Gonadotrophin], hCG) responsible for feedback maintainance of the corpus luteum (in maternal ovary) and therefore maintaining early pregnancy.
:(More? [http://embryology.med.unsw.edu.au/Notes/week2.htm Week 2 Notes] | [http://embryology.med.unsw.edu.au/Notes/placenta.htm Placenta Notes] | [C.htm#human_chorionic_gonadotrophin human Chorionic Gonadotrophin])
===syncytin===
:(human endogenous retrovirus, HERV) envelope gene of a human endogenous defective retrovirus and a factor specifically expressed in syncytiotrophoblasts with several suggested roles. 1. may contribute towards immune tolerance of the developing embryo (human syncytin-2 and mouse syncytin-B). 2. may mediates cell-cell fusion to initially form multinucleated syncytiotrophoblast from cytotrophoblasts on the trophoblast layer (shell) of the implanting conceptus (human syncytin-1 and mouse syncytin-A).
:(More? [http://embryology.med.unsw.edu.au/Notes/week2.htm Week 2 Notes] | [http://embryology.med.unsw.edu.au/Notes/placenta.htm Placenta Notes] | [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=604659 OMIM])
===symphysiotomy===
:An operation carried out to increase the size of the pelvic outlet to permit vaginal delivery of a baby.
:(More? [http://embryology.med.unsw.edu.au/Child/symphysiotomy.htm Birth - Symphysiotomy] | [http://embryology.med.unsw.edu.au/Child/Birth1.htm Birth])
===syndactyly===
:(Greek, ''syn'' = together; ''daktulos'' = finger or digit) webbing between fingers which may be single or multiple and may affect: skin only, skin and soft tissues or skin, soft tissues and bone.
:(More? [http://embryology.med.unsw.edu.au/Notes/skmus72.htm#Syndactyly Limb Abnormalities])
===synoviolin===
:(Synovial Apoptosis Inhibitor 1, SYVN1, HRD1) protein enzyme (ubiquitin ligase) expression is induced by the unfolded protein response (UPR) following an endoplasmic reticulum (ER) stress. Protein is also overexpressed in the synovial cells of patients with rheumatoid arthritis.
:(More? [http://embryology.med.unsw.edu.au/Notes/skmus31.htm Joint Development] | [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=608046 OMIM - Synovial Apoptosis Inhibitor 1])
===syphilis===
:disease caused by the bacterium ''Treponema pallidum'', a spirochete with a relatively small genome and requires a host to survive. First recognized in the 15th century in Europe, it can kill early fetuses or produce congenital deafness in older fetuses.
:(More? [http://embryology.med.unsw.edu.au/Defect/bacteria.htm#Syphilis Abnormal Development - Bacterial Infection])
===syringocele===
:(Greek, ''syringo'' = tube, ''cele'' = swelling) an abnormality of duct systems. For example, seen in bulbourethral gland with dilatation of the Cowper's duct.
:(More? [http://embryology.med.unsw.edu.au/Notes/genitalXYglands.htm Genital Male - Accessory Glands])
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Latest revision as of 21:57, 16 July 2020

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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

R

R-banding

A genetics term used to describe a technique for staining chromosomes during metaphase. The resulting banding pattern is the opposite of G-banding and there are several other chromosome staining techniques.
(More? Molecular Development - Genetics)

radial hemimelia

Clinical term for a congenital abnormality characterised by the partial or complete absence of the radius.
(More? Limb Abnormalities | PMID 18950501)

raphe

Anatomical line of fusion of the urogenital folds lying along the urethra and scrotum in male external genitalia.
(More? Genital System Development)

Rathke's pouch

An ectodermal fold in roof of pharynx forming anterior pituitary (adenohypophysis) and pars intermedia. Named after German embryologist and anatomist Martin Heinrich Rathke (1793 -1860).


(More? Endocrine - Pituitary Development | Endocrine Development | Martin Heinrich Rathke)


Rauber's layer

A thinned-out trophoblast membrane over the embryonic disk in developing carnivores and ungulates. In cattle, prevention of the loss of the polar trophoblast layer leads to ectopic domains of BRACHYURY, a gastrulation marker. Named after August A. Rauber (1841-1917) a German anatomist.
(More? trophoblast | PNAS)

receptor

General term generally for the cellular proteins which specifically bind a ligand or a number of ligands in signal transduction. Associated in many forms of signaling including: developmental, neural, neuromuscular and endocrine signaling. Receptors can be found embedded in cell membranes, cytoplasmic, nuclear and on organelles.

receptor protein tyrosine phosphatase

(RPTP) A family of enzyme phosphatases that control aspects of nervous system development. Phosphatases remove phosphate groups from substrates, mainly proteins, and have the opposite enzymatic activity to kinases. Drosophila have 6 different RPTPs including leukocyte antigen-related (LAR) involved in photoreceptor axon targeting independent of its phosphatase activity.
(More? PMID 19889974)

receptor tyrosine kinase-like orphan receptor

(Ror2, Neurotrophic tyrosine kinase, receptor-related 1, NTRKR1) A cell surface receptor protein suggested to interact with wnt5a in developmental signal transduction. The receptor activates multiple downstream intracellular mediators.
(More? OMIM 602336)
rectouterine pouch
rectouterine pouch

rectouterine pouch

(Pouch of Douglas or rectovaginal) Anatomical description of the female peritoneal cavity lying between the back wall of the uterus and rectum.
(More? Coelomic Cavity Development | Uterus Development

recurrent pregnancy loss

(RPL) Clinical term for 3 or more consecutive miscarriages and is suggested as due to a range of maternal and embryonic causes.

reduced fetal movement

A diagnostic term for referring to an analysis of fetal movements during the third trimester. There are a wide range of different methodologies and criteria associated with this technique.
(More? Third Trimester | Ultrasound)

reductive division

Cell division term describing meiosis where diploid DNA content becomes haploid (halved).
(More? Meiosis)

reelin

(Reln, RL) A protein required for neuronal migration and cellular layer formation during brain development. Mutation in the mouse model lead to impaired motor coordination, tremors, and ataxia. Reelin is an extracellular protein involved in signaling through the Dab1 adapter protein, and Lis1 regulate neuronal migration and cellular layer formation in the brain. The genomic structures of the mouse and human RELN genes appear to be highly conserved and the loss of Reelin and reduction in Lis1 activity in both mice and humans results in the disorganization of cortical structures.
(More? Neural System Development | OMIM - REELIN)

regulatory sequence

(regulatory region, regulatory area) Genetic term describing a segment of DNA where regulatory proteins such as transcription factors can bind preferentially. The regulated gene can either increase or decrease expression following binding of these factors.
(More? Molecular Development)
Reichert's cartilage
Reichert's cartilage

Reichert's cartilage

(second pharyngeal arch cartilage) Neural crest within the second pharyngeal arch forming this cartilage band. The dorsal ends form the middle ear ossicle (stapes) and temporal bone styloid process, the ventral part ossifies to form hyoid bone components of the lesser cornu and superior body. A study (PMID 16441562) suggest that this is not a continuous band (like Meckel’s) but a series of segments and mesenchymal tissue. Named after Karl Bogislaus Reichert (1811 – 1883) a German anatomist.
(More? Middle Ear | Head Development)

Reichert's membrane

In early rodent development, a thick multilayered basement membrane between the parietal endoderm cells and the trophoblast cells. This membrane has contentious origins, and has been suggested to begin with the formation of a basement membrane of the mural trophoblast cells, subsequent growth is from primitive endoderm cell depositions.
(More? Mouse Development | PMID 8651512)

relative risk

(risk ratio or odds ratio) Term used in describing the effect of environmental teratogens on development. The ratio of the rate of the condition among the exposed and the non-exposed population. (e.g. smokers risk of having a low birth weight baby compared to non-smokers) A high relative risk may indicate a low absolute risk if the condition is rare. The other risk descriptor term used to describe the likelyhood of an abnormality is absolute risk.
(More? Environmental Abnormal Development)

relaxin

The reproductive hormone involved in uterine relaxation (some species), reproductive tissue growth, connective tissue remodeling (collagen), cardiovascular, renal system, and brain. Relaxin receptor is G-protein-coupled receptor (relaxin family peptide receptors 1 - 4, RXFP1-4).
(More? Genital System Development)
Early fetal kidney
Renal (=kidney)

renal

(Latin, renes = "kidney") Term used in relation to the kidney and associated structures (renal pelvis, renal artery)
(More? Renal System Development | Lecture - Renal Development)

repolarization

Term used in relation to the heart, repolarization is a term used to describe the relaxation after each cardiac contraction which is controlled by a gradient of ion channels.
(More? Cardiovascular System Development)

Reprotox

A commercial online database that contains summaries on the effects of medications, chemicals, infections, and physical agents on pregnancy, reproduction, and development.
(More? REPROTOX | Abnormal Development - Environmental)

respiratory

Term used in relation to breathing (in and out) or associated with the lungs. Anatomically used to describe the lungs, air pathways and associated muscles. In cell biology used in relation to mitochondrial use of oxygen to produce energy and carbon dioxide waste.
(More? Respiratory System Development)

RESOLVE

A national, nonprofit consumer organization offering education, advocacy, and support to those experiencing infertility. Services include a national HelpLine, quarterly newsletter, extensive literature list, member-to-member contact systems, and local support groups through a network of over 50 chapters nationwide.

resorptive bay

Osteoclast resorptive bay
Osteoclast resorptive bay
(Howship's lacuna) The histological name for the shallow bay or cavity lying directly under an osteoclast located at the site of bone remodeling. This microscopic extracellular matrix space represents the site of bone matrix resorption by the osteoclast.
(More? Histology Image - Osteoclast | Bone Histology | Bone Development Practical | Lecture - Musculoskeletal Development)

respiratory embryonic stage

respiratory embryonic stage
respiratory embryonic stage
(lung bud stage) The earliest stage of lung development when the two lungs are primitive "buds" growing into the future pleural cavity.
Lung Stages: respiratory embryonic stage - pseudoglandular stage - canalicular stage - terminal sac stage - alveolar stage
(More? Respiratory System Development | Lecture - Respiratory Development)

respiratory tree

Anatomical term to describe the components of the respiratory system (lungs) as they branch again and again ending in the functional units, the alveolar sacs (alveolus).
(More? Respiratory System Development)

retained products of conception

Where part of the placenta or fetal membranes remains within the uterus, often associated with early fetal loss in the first trimester (previously called incomplete abortion).

rete ovarii

(Latin, rete = "net", refers to a network) A group of epithelial tubules located at the hilum of the ovary possibly mesonephric origin.
(More? Ovary Development)

rete ridge

(Latin, rete = "net", refers to a network) Integumentary histology term describing the extensions of the epidermis into the dermis. These epidermal surface thickenings extend downward between underlying connective tissue dermal papillae. This is also the site of initial eccrine gland differentiation.
(More? Integumentary System Development)

rete testis

(Latin, rete = "net", refers to a network) The duct (epithelial tubules) conduction system for spermatazoa embedded within the mediastinum (connective tissue) located in the center of the testis (male gonad) derived from the mesonephric duct, and allow spermatazoa to travel from the seminiferous tubules to the vasa efferentia.
Spermatozoa Duct Pathway: seminiferous tubule - straight tubule - rete testis - ductuli efferentes - ductus epididymidis - ductus deferens
(More? Lecture - Genital Development)

retina

The stratified sensory structure of the eye, formed from the neural ectoderm that extends from the forebrain (diencephalon) to form initially the folded optic cup. Vertebrates have ten identifiable layers formed from nerve fibers, neurons, membranes, photoreceptors and pigmented cells. Light must pass through nearly all these layers to the photoreceptors.
(More? Retina Development | Sensory - Vision Development)

retinal pigment epithelium

(RPE) An epethial pigmented cell layer lying outside the sensory retina, formed from the outer layer of the folded optic cup. The RPE is firmly attached to the underlying choroid and overlying retinal visual cells, for which it has a nutritional role.
(More? Retina Development | Sensory - Vision Development)

retinal waves

A form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) along with EphA/ephrin-A signaling are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells.
(More? Retina Development | Sensory - Vision Development)

retinopathy of prematurity

(ROP) A treatable vascular proliferative disorder that affects the incompletely vascularized retina in premature neonates, birth weight 1250 grams or less and born before 31 weeks gestation GA are at highest risk. Classified as type 2 progressing to type 1, this is a primary cause of childhood blindness. Due to retinal immaturity, neovascularization occurs leading to retinal traction and retinal detachment, eventually affecting vision.
(More? Vision Abnormalities | Birth - Preterm | Sensory - Vision Development | NIH - ROP | American Association for Pediatric Ophthalmology)

retrograde menstruation

Term describing the passage of menstrual blood into the uterine tubes and peritoneal cavity during menses.
(More? Menstrual Cycle)

Rett syndrome

(RTT) A severe neurodevelopment disorder, with intellectual disability and abnormalities of movement, mainly caused by mutations in the X-linked (Xq28) Methyl-CpG-binding protein 2 (MECP2) gene and therefore almost exclusively in females. The congenital variant of Rett syndrome is caused by heterozygous mutation in the FOXG1 gene on chromosome 14q13.
(More? Neural System - Abnormalities | Neural System Development | OMIM - Congenital Rett syndrome | OMIM - Rett syndrome)

Rhesus D

(RhD, Rh factor) See Rh factor below. The protein on surface of red blood cells in some blood types (Rh+) and absent in others (Rh-). Can cause erythroblastosis fetalis in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy.

rheumatic fever

Term for an acute disease that affects mainly children and young adults. It is a reaction to a throat infection by a particular bacteria and can damage the: heart (rheumatic heart disease, damaging muscle, valves and lining), joints and the brain.
(More? Cardiovascular System Development)

rheumatoid arthritis

A chronic inflammatory autoimmune disease in which the immune system attacks the tissues lining the joints. The inflamed joints often cause pain, heat and swelling and can lead to functional limitations and severe disability.

Rh factor

(Rh) The protein on surface of red blood cells in some blood types (Rh+, Rh positive) and absent in others (Rh-, Rh negative). Can cause fetal erythroblastosis (erythroblastosis fetalis or Haemolytic Disease of the Newborn) in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy. Clinical guidelines in some countries recommend anti-D immunoglobulin therapy for all pregnant women who are RhD negative, regardless of the rhesus status of the fetus. Non-Invasive Prenatal Testing (NIPT) may in future allow testing of the fetal rhesus status.
(More? Blood Development | Non-Invasive Prenatal Testing)

Rho1

A small GTPase of the Rho subfamily (Rho, Rac and Cdc42) acts as regulatory switch for actin cytoskeleton. In development, activated in epithelial cells for invagination.
(More? Molecular Development)

rhombencephalon

(Greek rhombos = rhomboid, enkephalos = brain, hindbrain) The hindbrain, the most caudal neural tube primary brain vesicle (there are 3 primary brain vesicles) that will form the two secondary brain vesicles, the metencephalon and the myelencephalon. These will in turn generate in the adult brain the cerebellum, pons and medulla. The rhombencephalon lumen (cavity of the neural tube) will form the fourth ventricle.
Primary brain vesicles: prosencephalon (forebrain) - mesencephalon (midbrain) - rhombencephalon (hindbrain)
(More? Lecture - Ectoderm Development)

rhombomere

Hindbrain rostrocaudal segmentation established by segmental expression of Hox homeodomain transcription factors. Histologically rhombomeres are visible as undulating folds (scalloping) of the neural tube in the hindbrain region and have associated cranial nerves.
(More? Lecture - Neural Development | Lecture - Ectoderm Development)

riboswitch

A type of molecular regulation in bacteria where an RNA element binds metabolites and then regulates gene expression. This type of regulation is usually cis, where a 5' untranslated region (5'UTR) riboswitch modulates transcription or translation of the downstream coding sequence.

rich club

A new neural pathway term that refers to brain regions that form a high-cost, high-capacity backbone thought to enable efficient network communication. This has been shown to differ in pre-term infants.
(More? Neural System Development | Preterm | PMID 24799693)

ricin

A highly potent toxin produced by castor beans, it contains a ribotoxic A chain (RTA) and a cell-binding B chain.

RNA retrovirus

A virus with genetic material stored in the form of RNA that can replicate in a host cell and then by reverse transcriptase produce DNA that is then incorporated into the host's genome.
(More? Abnormal Development - Viral Infection)

RNA silencing

(RNA interference, RNAi, microRNA, miRNA) Molecular development term describing the complex of mechanisms that regulate gene expression through small RNA molecules, in mammals this is mainly the microRNA (miRNA) pathway. These short RNA molecules, produced by RNAse III family enzyme Dicer, guide sequence-specific silencing of gene expression to suppress mRNA translation into protein. This mechanism has also been identified in early development during week 1 in zygote to blastocyst formation.


(More? Molecular Development)

Robinow syndrome

A skeletal dysplasia characterized by short stature, limb shortening, genital hypoplasia, and craniofacial abnormalities. Has both autosomal dominant and autosomal recessive (original family described by Meinhard Robinow) inheritance patterns. Recently, two different missense mutations in Wnt5a have been identified with the autosomal dominant Robinow syndrome, resulting in decreased Wnt5a activity.
(More? OMIM 268310)

Robson classification

(10 group classification) A clinical term for a caesarean delivery classification system first described by Robson in 2001.
(More? Caesarean Classification | caesarean | PMID 11359322)

roof plate

The term used to describe the thin dorsal region of the early neural tube forming the central nervous system (brain and spinal cord). The roof plate also lies adjacent to the dorsal ectoderm and initial neural crest prior to migration. The opposite side of the early neural tube forms the floor plate and the lateral parts are divided into two thicker regions, the alar plate and basal plate.
(More? Lecture - Ectoderm Development | Neural System Development)

Ror2

An acronym for receptor tyrosine kinase-like orphan receptor.
(More? Molecular Development

rostral neuropore

(cranial, cephalic or anterior) See cranial neuropore.
(More? Neural System Development)

rostrocaudal

Anatomical axis term used to describe a head (rostral) to tail (caudal) direction or sequence of developmental events. Some embryonic structures form initially in a rostral (head-ward) region and later similar structures form more caudal (tail-ward). Examples include somite formation (somitogenesis), limb and pharyngeal arch development.

rotavirus

Rotavirus
Rotavirus
A type of virus that is a common cause of diarrhoea and vomiting in infants and young children. The live attenuated rotavirus vaccine is contraindicated in pregnancy, but can be safely administered to household contacts of pregnant women. There is only a very small risk of transmission of the rotavirus vaccine virus to a susceptible pregnant woman and there is no evidence of risk to the fetus if pregnant women are in contact with recently vaccinated individuals. (data based on: The Australian Immunisation Handbook 9th Edition 2008 2.3.2 Vaccination of women planning pregnancy, pregnant or breastfeeding women, and preterm infants - updated July 2009 )
(More? Viral Infection | 2.3.2 Vaccination of women planning pregnancy, pregnant or breastfeeding women, and preterm infants - updated July 2009 | The Australian Immunisation Handbook 9th Edition 2008)

RU 486

(mifepristone) Clinical potent hormone progesterone and glucocorticoid receptor antagonist used as a birth control drug. Progesterone binding to the progesterone receptor generates a receptor conformational change allowing it to bind to DNA and act as a transcription factor for genes. RU486 binds with 10-fold higher affinity the same receptor C-terminal region of the hormone-binding domain and then does not act as a transcription factor.
(More? Mifepristone)

rubella

Infant rubella virus
Infant rubella virus
(Latin, rubella = little red) Virus also known as "german measles" (due to early citation in German medical literature). This virus can crosses the placenta from infected mothers and leads to major developmental defects in many different developing systems, including vision and hearing.
(More? Abnormal Development - Rubella Virus)

rugae palatinae

Mouse palatal rugae
Mouse palatal rugae
(palatal rugae) The transverse ridges forming on the secondary palate which are also sequentially added as the palate grows.
(More? Palate Development | Cleft Palate | Cleft Lip and Palate | Head Development)

Runx1

(Acute Myeloid Leukemia 1, AML1) Transcription factor of the Runt-related protein family (3 members in the mammalian family). Runx1 can act as a context-dependent transcriptional activator or repressor. In neural development, expressed in post-mitotic neurons and plays important roles in both phenotype specification and axonal targeting. AML1 is one of the most frequent targets of chromosome translocations associated with leukemia.
(More? Neural System Development | Molecular Development | OMIM - Runx1)


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. (2024, June 1) Embryology R. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/R

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