has tissue from all three germ layers . The image shows tissue derived from the mesoderm ... refined the germ cell layer concept, and introduced into English were the terms mesoderm by T. H ... from flatworms to humans are triploblastic , possessing a mesoderm in addition to the germ layers found ... this goes on to form the amnion . The epiblast keeps moving and forms a second layer, the mesoderm ..., and the intestines. Mesoderm Image Mesoderm.png thumb 275px The mesoderm aids in the production ... blood cell s. main Mesoderm The mesoderm germ layer forms in the embryo s of triploblastic animal s. During gastrulation , some of the cells migrating inward contribute to the mesoderm , an additional layer between the endoderm and the ectoderm . The formation of a mesoderm led to the development ... wall while fluid cushions and protects them from shocks. The mesoderm forms skeletal muscle, the skeleton ... more details
Schizocoely adjective forms schizocoelous or schizocoelic is a process by which some animal embryonic development embryos develop . Animal s which develop through schizocoely are known as schizocoelomates . Schizocoely occurs when a coelom body cavity is formed by splitting the mesoderm al embryonic tissue. ref name moore Cite book url http books.google.cz books?id bZw ntFxp YC&dq coelom&as brr 3&source gbs navlinks s publisher Cambridge University Press isbn 0521857368, 9780521857369 last Moore first Janet coauthors Raith Overhill title An introduction to the invertebrates date 2006 ref Schizocoelous development is typically attributed to protostomes ref name moore phyla Mollusca , Annelida , and Arthropoda , but some deuterostomes can exhibit schizocoely as well. NOTE TO EXPERT EDITOR This still doesn t make any sense. Saying it is exclusive is NOT compatible with saying that some deuterostomes can exhibit it. Unless you mean to suggest that Schizocoelous development is different from schizocoely , in which case you need to explain. ... Better now? The term refers to the order of organization of cells in the gastrula leading to development of the coelom . In these three phyla of organisms, the mesoderm the middle germ layer forms as a solid mass of migrated cells from the single layer of the gastrula. The new mesoderm then splits, creating the pocket like cavity of the coelom. References references See also Embryology Enterocoely External links Enterocoelous and schizocoelous conditions http www.utm.edu departments cens biology rirwin enteroschizo.htm UTM.edu Category Developmental biology developmental biology stub cs Schizocoel de Schizocoelie es Esquizocelia fr Schizoc lie it Schizocelia pt Celoma esquizoc lico ... more details
embryos. The pronephric primordium develops from the intermediate mesoderm , lying between the paraxial mesoderm paraxial somitic mesoderm and the lateral plate . In many organisms e.g. amphibians ... it forms along the length of the intermediate mesoderm e.g. zebrafish . Drainage In both amphibians ... mesoderm does form and links up to the cloaca. This duct is known as the pronephric duct, mesonephric ... more details
the mesoderm of the trilaminar embryo . The trilaminar embryo consists of three relatively flat layers of ectoderm , endoderm also known as entoderm and mesoderm . As the embryo develops, the mesoderm starts to segment into three main regions the paraxial mesoderm , the intermediate mesoderm and the lateral plate mesoderm . The lateral plate mesoderm later splits in half to form two layers bounding ... more details
Infobox Embryology Name Ventral mesentery Latin GraySubject 241 GrayPage 1103 Image Gray984.png Caption The primitive mesentery of a six weeks human embryo, half schematic. Image2 Gray989.png Caption2 Schematic figure of the bursa omentalis, etc. Human embryo of eight weeks. System CarnegieStage Precursor GivesRiseTo MeshName MeshNumber DorlandsPre m 10 DorlandsSuf 12526439 Ventral mesentery is the part of the peritoneum closest to the navel . Development The cephalic portion of the septum transversum takes part in the formation of the Thoracic diaphragm diaphragm , while the caudal portion into which the liver grows forms the ventral mesentery or ventral mesogastrium , when referring to the portion at the stomach . ref name gray Gray s anatomy ref The lesser omentum is formed, by a thinning of the mesoderm or ventral mesogastrium, which attaches the stomach and duodenum to the anterior abdominal wall . By the subsequent growth of the liver this leaf of mesoderm is divided into two parts, viz., the lesser omentum between the stomach and liver, and the falciform and coronary ligament s between the liver and the abdominal wall and diaphragm. ref name gray Image Gray1038.png left 300px thumb Mesentery in red. Ventral mesentery is the upper part of the circuit. The lower part is dorsal mesentery . References references Development of digestive system Peritoneum Developmental biology stub Category Abdomen ... more details
Infobox Embryology Name PAGENAME Latin ductus pronephricus GraySubject 252 GrayPage 1205 Image Caption Image2 Caption2 System Precursor intermediate mesoderm GivesRiseTo Wolffian duct MeshName MeshNumber Code Terminologia Embryologica TE E5.6.1.0.0.0.5 The pronephric duct is the predecessor of the Wolffian duct . Development The development of the pronephric duct is a part of the development of the urinary and reproductive organs . In the outer part of the intermediate mesoderm , immediately under the ectoderm, in the region from the fifth cervical segment to the third thoracic segment , a series of short evaginations from each segment grows dorsally and extends caudally , fusing successively from before backward to form the pronephric duct. This continues to grow caudalward until it opens into the ventral part of the cloaca beyond the pronephros it is termed the Wolffian duct . Thus, the Wolffian duct is what remains of the pronephric duct after the atrophy of the pronephros. See also pronephros External links http mcb.berkeley.edu courses mcb131 handouts Harland kidneylung.htm Diagram at berkeley.edu http www.xenbase.org xmmr Marker pages crest ets 1.html Photos at xenbase.org developmental biology stub Development of urinary and reproductive systems Category Embryology of urogenital system ... more details
Infobox Embryology Name Tubular heart Latin cor tubulare GraySubject GrayPage Image Gray461.png Caption Diagram to illustrate the simple tubular condition of the heart. Image2 Gray462.png Caption2 Heart of human embryo of about fourteen days. System CarnegieStage Days 21 Precursor splanchnic mesoderm GivesRiseTo MeshName MeshNumber Code Terminologia Embryologica TE E5.11.1.1.1.0.5 The tubular heart or primitive heart tube is the earliest stage of heart development. From the inflow to the outflow, it consists of sinus venosus , primitive atrium , the primitive ventricle , the bulbus cordis , and truncus arteriosus . ref Cite web url http www.pubmedcentral.nih.gov articlerender.fcgi?artid 1767109 title Development of the human heart days 15 21 accessdate 2007 09 18 format work ref It forms primarily from splanchnic mesoderm . ref Cite web url http isc.temple.edu marino embryology Heart98 heart text.htm title Text for Cardiovascular Development accessdate 2007 09 18 work ref More specifically, they form from Endocardial heart tube endocardial tubes , starting at day 21. ref Cite web url http www.meddean.luc.edu Lumen meded grossanatomy thorax0 heartdev tube.html title Heart Tube Formation accessdate 2007 09 18 work ref References references External links EmbryologyTemple Heart98 heart97a sld018 EmbryologyTemple Heart98 heart97a sld019 Development of circulatory system Category Embryology of cardiovascular system Anatomy stub es Tubo card aco primitivo pl Cewa sercowa ... more details
Cloacal exstrophy is a severe birth defect wherein much of the abdominal organs the urinary bladder bladder and intestines are exposed. It often causes the splitting of both male and female genitalia specifically, the penis and clitoris respectively , and the anus is occasionally sealed. Cloacal exstrophy is an extremely rare birth defect, present in only one in 200,000 pregnancies one in 400,000 live births. It is caused by a defect of the ventral body wall mesoderm al migration is inhibited and folding fails. See also Bladder exstrophy External links LoyolaMedEd urology cloaexst.htm eMedicine ped 2924 Category Congenital disorders ... more details
Infobox embryology Name PAGENAME Latin blastocystis trilaminaris GraySubject GrayPage Image Caption Image2 Caption2 MeshName MeshNumber Code Terminologia Embryologica TE E6.0.1.1.4.0.1 A trilaminar embryo or trilaminary blastoderm , or trilaminar germ disk is an early stage in the development of triploblastic organisms, which include humans and many other animals. It is an embryo which exists as three different germ layer s the ectoderm , the mesoderm and the endoderm . These layers are arranged on top of each other like a stack of paper, giving rise to the name trilaminar , or three layered . It arises early in the third week, after gastrulation . External links eMedicineDictionary trilaminar blastoderm EmbryologySwiss hdisqueembry triderm01 EmbryologyUNSW Notes week3 4 http staff.um.edu.mt acus1 Gasrtrulation.htm Overview at edu.mt Embryology Category Embryology developmental biology stub ... more details
PBB geneid 145873 Mesoderm posterior protein 2 MESP2 , also known as class C basic helix loop helix protein 6 bHLHc6 , is a protein that in humans is encoded by the MESP2 gene . ref name entrez cite web title Entrez Gene mesoderm posterior 2 homolog mouse url http www.ncbi.nlm.nih.gov sites entrez?Db gene&Cmd ShowDetailView&TermToSearch 145873 accessdate ref Function This gene encodes a member of the basic helix loop helix bHLH family of transcription factor s and plays a key role in defining the rostrocaudal patterning of somite s via interactions with multiple Notch signaling pathway s. This gene is expressed in the anterior presomitic mesoderm and is downregulated immediately after the formation of segmented somites. This gene also plays a role in the formation of epithelial somitic mesoderm and cardiac mesoderm. ref name entrez Clinical significance Mutations in the MESP2 gene cause autosomal recessive Spondylocostal dysostosis type 2. ref name pmid18485326 cite journal author Cornier AS, Staehling Hampton K, Delventhal KM, et al. title Mutations in the MESP2 gene cause spondylothoracic dysostosis Jarcho Levin syndrome journal Am. J. Hum. Genet. volume 82 issue 6 pages 1334 41 year 2008 month June pmid 18485326 pmc 2427230 doi 10.1016 j.ajhg.2008.04.014 url http linkinghub.elsevier.com retrieve pii S0002 9297 08 00274 7 ref References reflist Further reading refbegin 2 cite journal author Strausberg RL, Feingold EA, Grouse LH, et al. title Generation and initial analysis of more than 15,000 full length human and mouse cDNA sequences. journal Proc. Natl. Acad. Sci. U.S.A. volume 99 issue 26 pages 16899 903 year 2002 pmid 12477932 doi 10.1073 pnas.242603899 pmc 139241 cite journal author Whittock NV, Sparrow DB, Wouters MA, et al. title Mutated MESP2 causes spondylocostal dysostosis in humans. journal Am. J. Hum. Genet. volume 74 issue 6 pages 1249 54 year 2004 pmid 15122512 doi 10.1086 421053 cite journal author Morimoto M, Kiso M, Sasaki N, Saga Y title Cooperative ... more details
from mesoderm only partly lines the fluid filled body cavity of these animals. Thus, although organs ... in place. Coelom main Coelom A coelom is a cavity lined by an epithelium derived from mesoderm . Organs ... cavity . The intraembryonic coelom is lined by somatic and splanchnic lateral plate mesoderm, while the extraembryonic coelom is lined by extraembryonic mesoderm. The intraembryonic coelom is the only ... known as schizocoely. The archenteron initially forms, and the mesoderm splits into two layers ... by enterocoely mesoderm buds from the walls of the archenteron and hollows to become the coelomic cavities ... lined with tissue derived from mesoderm. This fluid filled space surrounding the internal organ ... more details
orphan date April 2010 In Xenopus laevis , the specification of the three germ layers endoderm , mesoderm and ectoderm occurs at the blastula stage. ref name Heasman Heasman, J., Quarmby, J., and Wylie, C.C. 1984 . The mitochondrial cloud of Xenopus oocytes the source of germinal granule material. Dev ... and mesoderm. On the other hand, only a few examples of genes that are required for ectoderm specification ... transitions from mesoderm to neural cell fates. EMBO J 25, 3664 3674. ref and FoxIe1 Xema . ref ... to be essential for suppression of mesoderm differentiation from pluripotent cells. ref name sasai Sasai, N., Yakura, R., Kamiya, D., Nakazawa, Y., and Sasai, Y. 2008 . Ectodermal factor restricts mesoderm ... fate and suppresses the mesoderm formation mediated by the signaling of Transforming growth factor ... signals that induce mesoderm originating from the vegetal pole. Ectodermin mRNA is enriched in the dorsal ... of extracellular TGF beta ligands, resulting in embryos lacking of mesoderm development. This model ... mesoderm development by lowering the genetic dosage of the main TGF beta ligand of the emrbyo, Nodal ... the epiblast from which the mesoderm, but not the AVE, derive left the AVE untouched but caused this time ... Xema activates epidermal differentiation and represses endoderm and mesoderm specific genes in animal ... FoxI1e Xema by selecting genes that were down regulated under mesoderm inducing signals in the ectoderm ... head transcription factor family, known to participate in mesoderm formation, eye development ref ... 132, 3885 3894. ref It has been proposed that Notch and or Nodal , expressed in the vegetal mesoderm ... of ectoderm specific genes, whereas FoxI1e over expression inhibits the formation of mesoderm ... and mesoderm, when injected with FoxI1e mRNA, they are able to express ectodermal specific markers ... factor complex with Smad2 and drives the expression of genes involved in mesoderm induction and activation ... for mesoderm differentiation. ref name sasai Identification of XFDL156 Construction of a cDNA library ... more details
Infobox Embryology Name Ectoderm Latin GraySubject 6 GrayPage 48 Image Ectoderm.png Caption Organs derived from ectoderm. Image2 Gray11.png Caption2 Section through embryonic disk of Vespertilio murinus . System CarnegieStage Days 16 Precursor GivesRiseTo MeshName Ectoderm MeshNumber A16.254.425.273 DorlandsPre DorlandsSuf The ectoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the mesoderm middle layer and endoderm most proximal layer , with the ectoderm as the most exterior or distal layer. ref Langman s Medical Embryology, 11th edition. 2010. ref It emerges first and forms from the outer layer of germ cells. Generally speaking, the ectoderm differentiates to form the nervous system spine, peripheral nerves and brain , ref http www.bioethics.gov reports stemcell glossary.html ref ref name simple http simple.wikipedia.7val.com wiki Mate ref tooth Tooth enamel enamel and the Epidermis skin epidermis the outer part of integumentary system integument . It also forms the lining of mouth, anus, nostrils, sweat glands, hair and nails. ref name simple In vertebrate s, the ectoderm has three parts external ectoderm also known as surface ectoderm , the neural crest , and neural tube . The latter two are known as neuroectoderm . Image Gray32.png thumb left Section through ovum imbedded in the uterine decidua clear See also Ectoderm specification Coelom Embryology Endoderm Gastrulation Mesoderm References Reflist Embryology Human cell types derived primarily from ectoderm Category Developmental biology Category Embryology Category Gastrulation developmental biology stub ar bg ca Ectoderma cs Ektoderm de Ektoderm es Ectodermo eo Ektodermo fr Ectoderme io Ektodermo it Ectoderma ht Ektod m hu Ektoderma nl Ectoderm no Ektoderm pl Ektoderma pt Ectoderme ro Ectoderm ru sk Ektoderma sr fi Ektodermi sv Ektoderm th tr Ektoderm uk zh ... more details
Infobox Embryology Name Somitomeres Latin somitomera GraySubject GrayPage Image Caption Image2 Caption2 System CarnegieStage 11 Days third gestation al week Precursor paraxial mesoderm GivesRiseTo somites MeshName MeshNumber Code Terminologia Embryologica TE E5.0.2.2.2.0.2 In the developing vertebrate embryo , the somitomeres or somatomeres ref name Nanci2008 cite book author Antonio Nanci title Ten Cate s oral histology development, structure, and function url http books.google.com books?id nLW3Ts TDpEC&pg PA25 accessdate 16 April 2010 year 2008 publisher Elsevier Health Sciences isbn 9780323045575 pages 25 ref are loose masses of paraxial mesoderm derived cell biology cells that form along each side of the neural tube towards the end of the third gestation al week. The approximately 50 pairs of somitomeres begin developing in the cranial head region, continuing in a caudal tail direction until the end of week four. Development The first seven somitomeres give rise to the striated muscles of the face , jaw s, and throat . The remaining somitomeres, likely driven by periodic expression of the hairy gene hairy gene, begin expressing adhesion proteins such as cadherin N cadherin and fibronectin , compact, and bud off forming somite s. The somites give rise to the vertebral column sclerotome , associated muscles myotome , and overlying dermis dermatome . There are a total of 37 somite pairs at the end of the fifth week of development, after the first occipital somite and 5 7 coccygeal somites disappear from the original 42 44 somites References reflist External links EmbryologySwiss hdisqueembry triderm07 look for Fig. 16 Embryology Category Embryology developmental biology stub ... more details
Infobox Embryology Name PAGENAME Latin nodus primitivus GraySubject 6 GrayPage 47 Image Caption Image2 Caption2 System CarnegieStage Days 17 Precursor GivesRiseTo MeshName MeshNumber DorlandsPre k 04 DorlandsSuf 12471954 The primitive knot or primitive node is the organizer for gastrulation in vertebrates. Diversity In bird s it is known as Hensen s node , and is named after its discoverer Victor Hensen . In amphibian s, it is known as Spemann s organizer , and is named after Hans Spemann who, with Mangold, first identified the organizer in 1924. ref name pmid17563072 cite journal author Garcia Fern ndez J, D Aniello S, Escriv H title Organizing chordates with an organizer journal Bioessays volume 29 issue 7 pages 619 24 year 2007 pmid 17563072 doi 10.1002 bies.20596 ref Development The primitive knot starts as a regional knot of cells that forms on the blastodisc immediately anterior to where the outer layer of cells will begin to migrate inwards an area known as the primitive streak . Posterior to the node is the primitive pit, where the cells of the epiblast the upper layer of embryonic cells initially begin to invaginate. This invagination expands posteriorly into the primitive groove as the cells layers continue to move into the space between the embryonic cells and the yolk. This differentiates the embryo into the germ layer s endoderm, mesoderm, and ectoderm. The primitive knot migrates posteriorly as gastrulation proceeds, eventually being absorbed into the tail bud. The Default Model The cells of the primitive node secrete many cellular signals essential for neural differentiation. After gastrulation the developing embryo is divided into ectoderm, mesoderm, and endoderm. The ectoderm gives rise to epithelial and neural tissue, with neural tissue being the default cell fate. Bone morphogenetic proteins BMPs suppress neural differentiation and promote epithelial growth. Therefore, the primitive node the dorsal lip of the blastopore secretes BMP antagonists, ... more details
MEST or Mest may refer to As an initialism Middle European Summer Time, obsolete variant name of the Central European Summer Time , a time offset MEST Scientology Matter, Energy, Space and Time , used in Scientology to refer to the physical universe MEST gene , a gene in humans that encodes the mesoderm specific transcript homolog protein Meltwater Entrepreneurial School of Technology , a school in Accra, Ghana Cystic nephroma , a type of begin kidney tumor also known as a mixed epithelial stromal tumor Message Exchange State Transfer , a protocol in service oriented architecture Other Mest , a pop punk band from Blue Island, Illinois Mest album , their third studio album Revenge , the Russian word for which is , rendered Mest in the Latin alphabet The Red Flute , a Soviet drama film with the Russian title Mest Soviet submarine M 200 , a short range attack submarine of the Soviet Navy Musti Tunisia , a former Roman city in northern Tunisia, also known as Mest Vem vet mest? Who Knows Best? , a Swedish game show disambig ... more details
Unreferenced date December 2009 Triploblasty is a condition of the blastula in which there are three primary germ layer s the ectoderm , mesoderm , and endoderm . The germ layers form during gastrulation of the blastula . Additionally, the term may refer to any ovum in which the blastoderm splits into three layers. citation needed date January 2011 All higher and intermediate animals from flat worms to humans , arise from a triploblastic ovum. Triploblastic organisms are organisms which develop from such an ovum. Generally speaking, triploblastic organisms belong to the Bilateria subregnum. Triploblastic organisms generally possess bilateral symmetry, which is where the clade Bilateria takes its name. Simpler animals qualified as diploblasty diploblastic , such as cnidaria which include jellyfish, corals and hydra , possess two germ layers. Even simpler animals such as sea sponge sponges within the formally termed Porifera phylum contain no true tissues. See also Embryo Category Developmental biology Developmental biology stub ca Triplobl stia de Triploblast es Tribl stico fr Triploblastique it Triploblastico pl Tr jwarstwowce pt Tribl stico ru ... more details
forms the ureter . As the cranial end of the bud extends into the intermediate mesoderm, it undergoes ... mesoderm in contact with the tips of the branching ureteric bud is known as the metanephrogenic blastema ... more details
Image Gray22.png thumb Human embryo of 2.6 mm. Image Gray458.png thumb Diagram of the vascular channels in a human embryo of the second week. After Eternod. The red lines are the dorsal aort continued into the umbilical arteries . The red dotted lines are the ventral aort , and the blue dotted lines the vitelline veins . Vitelline circulation refers to the system of blood flowing from the embryo to the yolk sac and back again. The yolk sac is situated on the ventral aspect of the embryo it is lined by endoderm , outside of which is a layer of mesoderm . It is filled with fluid, the vitelline fluid , which possibly may be utilized for the nourishment of the embryo during the earlier stages of its existence. Blood is conveyed to the wall of the sac by the primitive aort , and after circulating through a wide meshed capillary plexus , is returned by the vitelline veins to the tubular heart of the embryo. This constitutes the vitelline circulation, and by means of it nutritive material is absorbed from the yolk sac and conveyed to the embryo. External links GrayPage 54 http www.med.umich.edu lrc coursepages M1 embryology embryo 13cardiovascular system.htm Overview of three circulation systems Gray s Category Embryology of cardiovascular system ... more details
Infobox Embryology Name PAGENAME Latin GraySubject 6 GrayPage 47 Image Gray977.png Caption Human embryo about fifteen days old. Brain and heart represented from right side. Digestive tube and yolk sac in median section. Buccopharyngeal membrane labeled in upper left. Image2 Caption2 System CarnegieStage Days Precursor GivesRiseTo MeshName MeshNumber DorlandsPre m 08 DorlandsSuf 12522482 The region where the crescentic masses of the ectoderm and endoderm come into direct contact with each other constitutes a thin membrane, the buccopharyngeal membrane or oropharyngeal membrane , which forms a septum between the primitive mouth and pharynx . In front of the buccopharyngeal area, where the lateral crescents of mesoderm fuse in the middle line, the pericardium is afterward developed, and this region is therefore designated the pericardial area . External links EmbryologyUNC hednk 020a developmental biology stub Gray s Development of digestive system Category Embryology of digestive system de Rachenmembran ... more details
Infobox Embryology Name PAGENAME Latin mesenchyma dermatomiale GraySubject GrayPage Image Gray64.png Caption Transverse section of a human embryo of the third week to show the differentiation of the primitive segment. ao. Aorta. m.p. Muscle plate. n.c. Neural canal. sc. Sclerotome. s.p. Dermatome . Image2 Caption2 System CarnegieStage Days Precursor GivesRiseTo dermis MeshName MeshNumber Code Terminologia Embryologica TE E5.17.1.0.2.0.2 The dermatomal mesenchyme or cutis plate is the dorsal portion of the paraxial mesoderm somite which gives rise to dermis . It is also known as the dermatome , but it should not be confused with the dermatomic area , which is also sometimes called a dermotome . The two concepts are related, but the cutis plate is an embryological structure, while the dermatomic area is present in the adult. External links EmbryologyUNSW Notes skmus6 EmbryologyUNSW Notes week3 6 http sprojects.mmi.mcgill.ca embryology earlydev week4 somites.html Gray s Development of integument Category Embryology Anatomy stub ... more details
Infobox Embryology Name PAGENAME Latin GraySubject GrayPage Image Ectoderm.png Caption Organs derived from ectoderm. Image2 Caption2 System CarnegieStage Days Precursor ectoderm GivesRiseTo MeshName MeshNumber DorlandsPre DorlandsSuf The surface ectoderm or external ectoderm forms the following structures human skin Skin only epidermis dermis is derived from mesoderm along with gland s, hair , and nail anatomy nail s Epithelium of the mouth and nasal cavity salivary glands, and glands of mouth and nasal cavity Tooth enamel as a side note, dentin and dental pulp are formed from ectomesenchyme which is derived from ectoderm specifically neural crest cells and travels with mesenchmyal cells Epithelium of pineal and pituitary glands Lens anatomy Lens , cornea , lacrimal gland , tarsal glands and the conjunctiva of the human eye eye Apical ectodermal ridge inducing development of the limb buds of the embryo. Sensory receptors in epidermis External links http cwx.prenhall.com bookbind pubbooks martini10 chapter18 custom3 deluxe content.html Gray s Anatomy stub Embryology Human cell types derived primarily from ectoderm Category Developmental biology Category Embryology ... more details
The pluriblast is a Pluripotency pluripotent population of Cell biology cells in the early mammal ian conceptus that is distinct from the trophoblast , and gives rise to the germ layer s of the embryo proper , as well as extraembryonic endoderm and extraembryonic mesoderm . Both the pluriblast and trophoblast arise from the Totipotency totipotent cells of the early conceptus. By definition, the pluriblast does not give rise to trophoblast cells during normal development, although it may retain this potential under experimental conditions. In most eutheria n mammals the pluriblast is termed the inner cell mass , as it forms a mass of cells within the fluid filled blastocyst , bounded by the trophoblast. However in metatherian marsupial mammals, and indeed in a small number of eutherian mammals, the pluriblast forms part of the blastocyst wall and no structure exists that can be described as an inner cell mass. Inner cell mass is thus a morphological term peculiar to the majority of eutherian mammals, whereas pluriblast is a functional term more widely applicable to conserved aspects of mammalian development. References Johnson MH and Selwood L 1996 . Nomenclature of early development in mammals. Reproduction, Fertility and Development. 8 759 764. Category Developmental biology ... more details
Image Kiemenbogen.jpg thumb Pattern of the branchial arches. I IV branchial arches, 1 4 branchial pouches inside and or pharyngeal grooves outside BR a Tuberculum laterale BR b Tuberculum impar BR c Foramen cecum tongue Foramen cecum BR d Ductus thyreoglossus BR e Sinus cervicalis The branchial apparatus is an embryological structure. ref name urlMedcyclopaedia Branchial apparatus cite web url http www.medcyclopaedia.com library topics volume vi 2 b branchial apparatus.aspx title Medcyclopaedia Branchial apparatus format work accessdate 2009 05 28 ref ref name urlLecture 24. Branchial Apparatus cite web url http www.med.howard.edu anatomy gas wk7 Lecture 2024.htm title Lecture 24. Branchial Apparatus format work accessdate 2009 05 28 ref It consists of branchial groove s from ectoderm branchial arch es from mesoderm pharyngeal pouch es from endoderm branchial membrane s References Reflist Embryology of head and neck Category embryology Category Developmental biology developmental biology stub ... more details
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