The following chart shows the products produced by the endoderm. class wikitable Germ Layer Category System Products Endoderm General ref The General category denotes that all or most of the animal ... tube, including those of the liver and pancreas Endoderm General Respiratory tract the Vertebrate trachea trachea , bronchi , and alveoli of the lungs Endoderm General Endocrine glands and organs the lining of the follicles of the thyroid gland and thymus Endoderm Auditory system the epithelium of the auditory tube and tympanic cavity Endoderm Urinary system the urinary bladder and part of the urethra ... cite journal author Zaret KS title Hepatocyte differentiation from the endoderm and beyond journal ... http linkinghub.elsevier.com retrieve pii S0959 437X 00 00234 3 ref The Endoderm has differentiated ... sinus tumor References reflist wiktionary endoderm Embryology Human cell types derived primarily from endoderm Gray s Category Developmental biology Category Embryology Category Gastrulation ar ca Endoderma cs Entoderm da Endoderm de Entoderm es Endodermo eo Endodermo fr Endoderme io Endodermo it Endoderma ht Andod m nl Endoderm pl Entoderma pt Endoderme ru sr fi Endodermi sv Endoderm th tr Endoderm uk zh ... more details
two layers, called the ectoderm and endoderm . Therefore, they are diploblastic . Animals with symmetry ... s biological tissue tissues and organ anatomy organ s through a process called organogenesis . Endoderm main Endoderm The endoderm is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner layer of the gastrula , which develops into the endoderm . Initially, the endoderm consists of flattened cells, which subsequently become columnar ... inward to form the endoderm form an additional layer between the endoderm and the ectoderm ... layer s. Production File Germ layers.png thumb 575px The endoderm produces tissue within the lung s, thyroid ... Germ Layer Category Product Endoderm General ref The General category denotes that all or most of the animal ... General Respiratory tract Endoderm General Endocrine glands and organs liver and pancreas Mesoderm ... of the Endoderm and Mesoderm Embryology Human cell types derived primarily from mesoderm ... more details
Enterocoely adjective forms enterocoelic or enterocoelous is a process by which embryonic development embryos develop . In enterocoely, a mesoderm is formed in a developing embryo , in which the coelom forms from pouches pinched off of the digestive tract also known as the embryonic gut, or archenteron . This type of coelom formation occurs in deuterostome animals, which for this reason are also known as enterocoelomates . Enterocoelous development begins once the embryo reaches the gastrula phase of development. At this point, there are two layers of cells the ectoderm outermost and the endoderm innermost layers. The mesoderm middle layer begins to form as two pockets of tissue one above the endoderm, and one below are formed via folding of the endoderm. These pockets begin to grow larger, and as they do so, they extend towards each other. When the two pockets of cells meet, the mesoderm is formed a complete layer of tissue right in between the endoderm and ectoderm layers. This then leads to the formation of a coelom . Enterocoelous development is the stage of embryological development of deuterostomes in which the coelom forms. The stage starts with the gastrula as the archenteron forms, pockets of migrating cells also form, creating another layer between the endoderm and ectoderm , the mesoderm . These pockets gradually expand to form the coelom. An exception to this form of coelom development is the subphylum vertebrata which are considered deuterostomes but exhibit schizocoelous coelom formation. In protostomes, the body cavity is formed by schizocoely . developmental biology stub See also Schizocoely External links http www.mhhe.com biosci pae glossaryd.html PAE Virtual Glossary Category Embryology es Enterocelia fr Ent roc lie it Enterocelia pt Celoma enteroc lico ... more details
Unreferenced stub auto yes date December 2009 Diploblasty is a condition of the blastula in which there are two primary germ layer s the ectoderm and endoderm . Diploblastic organisms are organisms which develop from such a blastula, and include cnidaria and ctenophora , formerly grouped together in the phylum Coelenterata, but later understanding of their differences resulted in them being placed in separate phyla. The endoderm allows them to develop true Biological tissue tissue . This includes tissue associated with the gut and associated glands. The ectoderm on the other hand gives rise to the epidermis, the nervous tissue, and if present, nephridia. Simpler animals, such as sea sponges , have one germ layer and lack true tissue organisation. All the more complex animals from flat worms to humans are triploblastic with three germ layers a mesoderm as well as ectoderm and endoderm . The mesoderm allows them to develop true Organ anatomy organs . See also Triploblasty Category Developmental biology Developmental biology stub ca Dibl stic es Dibl stico fa fr Diploblastique nn Diploblastiske dyr pl Dwuwarstwowce sv Diploblastica ... more details
In the Embryogenesis development of Vertebrate vertebrate animals , the prechordal plate is a uniquely thickened portion of the endoderm that is in contact with ectoderm immediately Anatomical terms of location Directional terms rostral to the cephalic tip of the notochord . ref http www.mondofacto.com facts dictionary?prechordal plate Mondofacto Online Medical Dictionary ref It is the most likely origin of the rostral cranial mesoderm. ref Seifert, R et al. J Anat 1993 183 75 89 ref References Reflist Category Developmental biology ... more details
move inward forming the endoderm red . Image Teratoma 2 low mag.jpg thumb right Micrograph of a teratoma ... tissue derived from the mesoderm immature cartilage left upper corner of image , endoderm gastrointestinal ... mesoderm by T. H. Huxley Huxley in 1871 and ectoderm and endoderm by Ray Lankester Lankester ... germ layers, the endoderm and ectoderm . Diploblastic animals are organized into recognisable tissues ... the primitive streak, dives down into it, and forms a new layer, called the endoderm , pushing the hypoblast ... 2011 Endoderm This section is linked from Liver Image Endoderm2.png thumb 200px The endoderm produces tissue within the lung s, thyroid , and pancreas . main Endoderm The endoderm is one of the germ ... layer of the gastrula, which develops into the endoderm . The endoderm consists at first of flattened ... and the follicle lining of the thyroid gland and thymus. The endoderm forms the stomach ... layer between the endoderm and the ectoderm . The formation of a mesoderm led to the development of a coelom ... more details
The primitive gut that forms during gastrulation in the developing blastula is known as the archenteron . It develops into the digestive tract of an animal. Formation of the Archenteron in Sea Urchins See Gastrulation . As primary mesenchyme cells detach from the vegetal pole in the blastula and enter the fluid filled cavity in the center the blastocoel , the remaining cells at the vegetal pole flatten to form a vegetal plate . This buckles inwards towards the blastocoel in a process called invagination . The cells continue to be rearranged until the shallow dip formed by invagination transforms into a deeper, narrower pouch formed by the gastrula s endoderm . This narrowing and lengthening of the archenteron is driven by convergent extension . The open end of the archenteron is called the blastopore . The filopodia thin fibers formed by the mesenchyme cells found in a late gastrula contract to drag the tip of the archenteron across the blastocoel. The endoderm of the archenteron will fuse with the ectoderm of the blastocoel wall. At this point gastrulation is complete, and the gastrula has a functional digestive tube. The indentation that is actually formed is called the lip of the blastopore in amphibian s and fish , and the primitive streak in bird s and mammal s. Each is controlled by the dorsal blastopore , and primitive node also known as Hensen s node , respectively. External links http chsweb.lr.k12.nj.us mstanley outlines animals antax image51.gif Diagram developmental biology stub Embryology Category Developmental biology ca Arqu nteron cs Prvost evo es Arqu nteron fr Archent ron it Archenteron ja pl Prajelito pt Arqu ntero ... 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. citation needed date January 2011 Simpler diploblasty diploblastic animals such as cnidaria which includes 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. This arose from the concept of multicellularity.with 3 primary layers used to describe a multicellular animal that has three primary germ layers ectoderm, endoderm, mesoderm during embryonic development. citation needed date January 2011 See also Embryo Category Developmental biology Developmental biology stub ca Triplobl stia es Tribl sticos fr Triploblastique it Triploblastico pl Tr jwarstwowce pt Tribl stico ... more details
Expand Spanish date July 2010 Infobox Embryology Name Hypoblast Latin GraySubject GrayPage Image Gray21.png Caption Section through the embryo. Hypoblast visible but not labeled. Image2 Cell differentiation gastrula.PNG Caption2 D points to the hypoblast. System CarnegieStage Days 8 Precursor inner cell mass GivesRiseTo endoderm MeshName MeshNumber Dorlands DorlandsID The hypoblast is a tissue type that forms from the inner cell mass . ref http embryology.med.unsw.edu.au Notes Index H.htm UNSW Embryology Glossary H Bot generated title ref It lies beneath the epiblast and consists of small cuboidal cells. ref Moore, K. L., and Persaud, T. V. N. 2003 . The Developing Human Clinically Oriented Embryology . 7th Ed. Philadelphia Elsevier. ISBN 0 7216 9412 8. ref Extraembryonic endoderm including Yolk sac is derived from hypoblast. References references External links http www.embryology.ch allemand iperiodembry carnegie02.html http www.med.umich.edu lrc coursepages M1 embryology embryo 04secondweek.htm http isc.temple.edu marino embryology EMBII97 sld005.htm Embryology Category Embryology anatomy stub de Hypoblast es Hipoblasto ... more details
Unreferenced stub auto yes date December 2009 S cells are cells which release secretin , found in the jejunum and duodenum . They are stimulated by a drop in pH to 4 or below in the small intestine s lumen. The released secretin will increase the secretion of HCO sub 3 sub sup sup into the lumen, via the pancreas . S cells are also one of the main producers of cyclosamatin . For more information on the function of S cells, see secretin . Gastrointestinal physiology Human cell types derived primarily from endoderm DEFAULTSORT S Cell Category Human cells Cell biology stub ru S ... more details
Unreferenced section date December 2007 Two types of pneumocytes also named pneumonocyte contribute to the maintenance of the alveoli of the lungs Type I pneumocyte s and Type II pneumocyte s. These cells function to aid in gas exchange, secretion of pulmonary surfactant , and self regeneration See also Dust cell External links KansasHistology resp resp17 BUHistology 13905loa http www.meddean.luc.edu lumen bbs p ppi10.html Electron micrograph at luc.edu Human cell types derived primarily from endoderm Category Respiratory system Category Thorax Category Human cells cell biology stub respiratory stub cs Pneumocyt fr Pneumocyte id Pneumosit it Pneumocita pl Pneumocyt pt Pneum cito ... more details
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
Sinus tubercle is the proliferation of endoderm induced by the paramesonephric ducts . The uterovaginal primoridium , which is a fusion of the caudal ends of paramesonephric ducts contacts the dorsal wall of the urogenital sinus and, induces the formation of the sinus tubercle. This occurs in both sexes In the female the mesonephric duct loses all association with the gonad and, disappears. It gives rise to the sino vaginal bulb s and, when it later becomes solid it is referred to as the vaginal plate . It likewise gives rise to the hymen , which eventually breaks down. In the males, the sinus tubercle gives rise to the seminal colliculus . References Moore Persaud, Medical embryology 2003 Development of urinary and reproductive systems Category Developmental biology Category Embryology ... more details
Image Germ layers.png thumb 400px The endoderm produces tissue within the lung s, thyroid , and pancreas . The mesoderm aids in the production of cardiac muscle , skeletal muscle , smooth muscle , tissues within the kidney s, and red blood cell s. The ectoderm produces tissues within the Epidermis skin epidermis and aids in the formation of neuron s within the brain, and melanocytes . In embryogenesis animal development , organogenesis organo genesis, compound of the Greek language Greek words that with which one works , ref http www.etymonline.com index.php?term organ Definition of organ from the Online Etymology Dictionary ref and origin, creation, generation ref http www.etymonline.com index.php?term genesis Definition of genesis from the Online Etymology Dictionary ref is the process by which the ectoderm , endoderm , and mesoderm develop into the internal organ s of the organism. Internal organs initiate development in humans within the 3rd to 8th weeks in utero. The germ layer s in organogenesis differ by three processes folds, splits, and condensation. Developing early during this stage in chordate animals are the neural tube and notochord . Vertebrate animals all differentiate from the gastrula the same way. Vertebrates develop a neural crest that differentiates into many structures, including some bones, muscles, and components of the peripheral nervous system . The coelom of the body forms from a split of the mesoderm along the somite axis . citation needed date January 2011 clear See also wiktionary organogenesis Ectoderm Embryogenesis Endoderm Eye development Germ layer Germ line development Heart development Histogenesis Limb development Mesoderm Morphogenesis References reflist Embryology Germ layer Category Developmental biology Category Embryology Category Greek loanwords ca Organog nesi de Organogenese es Organog nesis fa id Organogenesis is L ff ramyndun it Organogenesi nl Organogenese ja pl Organogeneza pt Organog nese ... more details
Infobox Embryology Name PAGENAME Latin GraySubject 6 GrayPage 50 Image Gray16.png Caption A series of transverse sections through an embryo of the dog. After Bonnet. Section I is the most anterior. In V the neural plate is spread out nearly flat. The series shows the uprising of the neural folds to form the neural canal. a. Aort . c. Intermediate cell mass. ect. Ectoderm. ent. Entoderm. h, h. Rudiments of endothelial heart tubes. In III, IV, and V the scattered cells represented between the endoderm and splanchnic layer of mesoderm are the vasoformative cells which give origin in front, according to Bonnet, to the heart tubes, h l.p. Lateral plate still undivided in I, II, and III in IV and V split into somatic sm and splanchnic sp layers of mesoderm. mes. Mesoderm. p. Pericardium. so. Primitive segment. Image2 Gray457.png Caption2 Transverse section through the region of the heart in a rabbit embryo of nine days. X 80. K lliker. j, j. Jugular veins. ao. Aorta. ph. Pharynx. som. Somatopleure. bl. Proamnion. ect. Ectoderm. ent. Entoderm. p. Pericardium. spl. Splanchnopleure. ah. Outer wall of heart. ih. Endothelial lining of heart. . Septum between heart tubes. System CarnegieStage 9 Days Precursor lateral plate mesoderm , endoderm GivesRiseTo mesenchyme MeshName MeshNumber DorlandsPre s 19 DorlandsSuf 12750717 In the anatomy of an embryo , the splanchnopleure is a structure created during embryogenesis when the lateral mesoderm splits into two layers. The inner or splanchnic layer adheres to the endoderm , and with it forms the splanchnopleure. See also Somatopleure External links EmbryologyUNC digest 022 EmbryologyUNC digest 023 http 207.62.207.35 vet02 vett2 vett2photos lecture module03 scan0004.jpg Diagram at Yuba Community College District http science.kennesaw.edu rmatson Biol 203350 Somatopleure.html Overview at Kennesaw State University developmental biology stub Gray s Embryology Category Embryology fr Splanchnopleure pt Esplancnopleura ... more details
Blood vessels first make their appearance in several scattered vascular areas that are developed simultaneously between the endoderm and the mesoderm of the yolk sac , i. e., outside the body of the embryo . Here a new type of cell, the angioblast or vasoformative cell , is differentiated from the mesoderm. These cells as they divide form small, dense syncytial masses, which soon join with similar masses by means of fine processes to form plexuses . Angioblasts are one of the two products formed from hemangioblasts the other being pluripotential hemopoietic stem cell s . External links GrayPage 505 http www.medicine.uiowa.edu creative portfolio.asp?recordID ILLUSTRATION&index 2 Diagram at uiowa.edu http www.brown.edu Courses BI0032 stemcell vascu.htm Development of the vascular system , at brown.edu http 7e.devbio.com article.php?ch 15&id 156 Alternative Sources Of Angioblasts Gray s Human cell types derived primarily from mesoderm Category Embryology ... 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 de Rachenmembran ... more details
Type I pneumocyte s simple squamous alveolar cells are responsible for gas exchange in the alveoli and cover a majority of the alveolar surface area 95 . While type I pneumocytes account for most of the surface area, they are approximately half as numerous as Type II pneumocyte type II cells , due to differences in size. Type I pneumocytes are large, thin cells stretched across a large surface area, while type II pneumocytes are smaller cells. Type I pneumocytes are unable to mitosis replicate and are susceptible to toxin toxic insults. In the event of damage, Type II cells can proliferate and or differentiate into type I cells to compensate. cell biology stub respiratory stub Human cell types derived primarily from endoderm Category Respiratory system Category Thorax Category Human cells ar ja I pt Pneum cito tipo I ... more details
unreferenced date September 2009 The stomochord is a flexible, hollow tube found in hemichordates . Stomochords were initially considered a variant of a primitive notochord , but are now recognized to not share histological composition to that of the notochord found in chordates. citation needed date September 2009 Stomochords arise in embryonic development as an outpocketing from the roof of the embryonic gut anterior to the pharynx. Then along came a gruffalo. In adults, they extend dorsally from the pharynx into the probiscis, and serve to communicate with the oral cavity. Their walls are composed primarily of epithelial cells , but ciliated and glandular cells are also present. citation needed date September 2009 div class metadata plainlinks stub style clear both background transparent This article is a Wikipedia Stub stub . You can help Wikipedia by fullurl FULLPAGENAME action edit expanding it . div Category Endoderm Category Histology cs Stomochord ... more details
Infobox Embryology Name PAGENAME Latin GraySubject 6 GrayPage 47 Image Gray991.png Caption Tail end of human embryo from fifteen to eighteen days old. Image2 Caption2 System Days 15 CarnegieStage 7 Precursor caudal end of the primitive streak GivesRiseTo MeshName MeshNumber DorlandsPre m 08 DorlandsSuf 12522517 The cloacal membrane is the membrane that covers the embryonic cloaca when still in the development of the urinary and reproductive organs . It is formed by ectoderm and endoderm coming into contact with each other. ref name urlEndoderm Developmental Biology NCBI Bookshelf cite web url http www.ncbi.nlm.nih.gov bookshelf br.fcgi?book dbio&part A3745 title Endoderm Developmental Biology NCBI Bookshelf format work accessdate ref After separation of the cloaca into the urogenital and anal parts, the cloacal membrane, in turn, is separated into a urogenital membrane and an anal membrane . It has been suggested that developmental errors may be associated with enlarged clitorises . ref name pmid19944238 cite journal author van der Putte SC title Penislike clitorises with megalourethras in nonvirilized female fetuses and a newborn. A histopathologic study and its bearing on their pathogenesis journal J. Pediatr. Surg. volume 44 issue 11 pages 2223 9 year 2009 month November pmid 19944238 doi 10.1016 j.jpedsurg.2009.07.024 url http linkinghub.elsevier.com retrieve pii S0022 3468 09 00582 X ref References reflist External links EmbryologySwiss hdisqueembry triderm04 EmbryologyUNC genital 021 http embryology.med.unsw.edu.au Medicine images stage11cloacal.jpg Diagram at unsw.edu.au http www.ana.ed.ac.uk anatomy humat notes embryo urogenital cloacal.htm Overview at ana.ed.ac.uk developmental biology stub Gray s Development of urinary and reproductive systems Development of digestive system Category Embryology ... more details
Myoepithelial cells sometimes referred to as Myoepithelium are Cell biology cells usually found in glandular epithelium as a thin layer above the basement membrane but generally beneath the lumen anatomy lumenal cells. These may be positive for ACTA2 alpha smooth muscle actin and can contract and expel the secretions of exocrine glands . They are found in the sweat gland , mammary gland , lacrimal gland , and salivary gland . Myoepithelial cells in these cases constitute the basal cell layer of an epithelium that harbors the epithelial Progenitor cell progenitor stem cells . In the case of wound healing , myoepithelial cells reactively cell growth proliferate . Presence of myoepithelial cells in a hyperplasia hyperplastic tissue proves the benign ity of the gland and, when absent, indicates cancer . Only rare cancers like adenoid cystic carcinoma s contains myoepithelial cells as one of the malignant components. It can be found in endoderm or ectoderm . ref name Berman2009 cite book author Jules J. Berman title Neoplasms principles of development and diversity url http books.google.com books?id WWnJ1 IM1yUC&pg PA207 accessdate 16 April 2010 year 2009 publisher Jones & Bartlett Learning isbn 9780763755706 pages 207 ref Markers Myoepithelial cells are true epithelial cell s positive for keratin s, not to be confused with myofibroblasts which are true mesenchymal cell s positive for vimentin . These cells are generally positive for alpha smooth muscle actin SMA , cytokeratin 5 6 and other high molecular weight cytokeratins, TP73L p63 and caldesmon . References reflist External links eMedicineDictionary Myoepithelium AnatomyAtlasesMicroscopic 07 141 Axillary Sweat Gland Myoepithelium OklahomaHistology 43 13 thick skin KansasHistology glands glands09 Simple Tubular Coiled GeorgiaPhysiology 6 6ch4 s6ch4 4 Human cell types derived primarily from endoderm Human cell types derived primarily from ectoderm Category Cell biology anatomy stub cs Myoepitel de Myoepithelzelle ja ... more details
Infobox Embryology Name Laryngotracheal groove Latin GraySubject 235 GrayPage 1071 Image Gray947.png Caption The head and neck of a human embryo thirty two days old, seen from the ventral surface. The floor of the mouth and pharynx have been removed. Laryngo tracheal tube labeled at lower left, second from bottom. Image2 Caption2 System CarnegieStage Days 28 Precursor endoderm ref http www.llu.edu llu medicine anatomy glossary syllabus resp.html LLU Medicine Anatomy Histology Mentor Respiratory Bot generated title ref GivesRiseTo MeshName MeshNumber DorlandsPre g 12 DorlandsSuf 12402602 The laryngotracheal groove is a precursor for the larynx and Vertebrate trachea trachea . The rudiment of the respiratory organs appears as a median longitudinal groove in the ventral wall of the pharynx. The groove deepens and its lips fuse to form a septum which grows from below upward and converts the groove into a tube, the Laryngotracheal groove or laryngo tracheal tube , the cephalic end of which opens into the pharynx by a slit like aperture formed by the persistent anterior part of the groove. Initially the cephalic end is in open communication with the foregut but eventually it becomes separated by indentations of mesoderm, the tracheoesophageal folds . When the tracheoesphageal folds fuse in the midline to form the tracheoesophageal septum , the foregut is divided into trachea ventrally and the esophagus dorsally. The tube is lined by endoderm from which the epithelial lining of the respiratory tract is developed. The cephalic part of the tube becomes the larynx, and its next succeeding part the trachea, while from its caudal end two lateral outgrowths, the right and left lung buds, arise, that branch into main primary , lobar secondary , segmental tertiary , and subsegmental bronchi and lead to development of the lungs.The Hox complex, FGF 10 fibroblast growth factor , BMP 4 bone morphogenetic protein , N myc a proto oncogene , syndecan a proteglycan , tenascin an extracel ... more details
The heart is the first functional organ in a vertebrate embryo. There are 5 stages to heart development. Specification of cardiac precursor cells Image Gray19.png center 450px frame The lateral plate mesoderm delaminates to form two layers the dorsal somatic parietal mesoderm and the ventral splanchnic visceral mesoderm. The heart precursor cells come from the two regions of the splanchnic mesoderm called the cardiogenic mesoderm . These cells can differentiate into endocardium which lines the heart chamber and valves and the myocardium which forms the musculature of the ventricles and the atria. The heart cells are specified in anterior mesoderm by proteins such as Dickkopf 1, Nodal, and Cerberus secreted by the anterior endoderm. Whether Dickkopf 1 and Nodal act directly on the cardiac mesoderm is the subject of research, but it seems that at least they act indirectly by stimulating the production of additional factors from the anterior endoderm. These early signals are essential for heart formation such that removal of the anterior endoderm blocks heart formation. Anterior endoderm is also sufficient to stimulate heart differientation since it can induce non cardiogenic mesoderm from more posterior positions in the embryo to form heart. The secretion of Wnt inhibitors such as Cerberus, Dickkopf and Crescent by the anterior endoderm also prevents Wnt3a and Wnt8 secreted by the neural tube from inhibiting heart formation. The notochord secretes BMP antagonists Chordin and Noggin to prevent formation of cardiac mesoderm in inappropriate places. Other cardiogenic signals such as BMP and FGF activate the expression of cardiac specific transcription factors such as homeodomain protein Nkx2.5 . Nkx2.5 activates a number of downstream transcription factors such as MEF2 and GATA which activate the expression of cardiac muscle specific proteins. Mutations in Nkx2.5 result in heart development defects and congenital heart malformations. Migration of cardiac precursor cells ... more details
orphan date April 2010 Vegetal Rotation is a Morphogenesis morphogenetic movement that drives mesendoderm internalization during gastrulation in amphibian embryos ref name winklbauer Winklbauer, R. and Sch rfeld, M., 1999. Vegetal rotation, a new gastrulation movement involved in the internalization of the mesoderm and endoderm in Xenopus . Development 126, 3703 3713. ref . The internalization of vegetal cells prior to gastrulation was first observed in the 1930s by Abraham Mandel Schechtman through the use of vital dye labeling experiments in Triturus torosus embryos ref Schechtman, A.M., 1934. Unipolar ingression in Triturus torosus A hitherto undescribed movement in the pregastrular stages of a urodele. Univ. Calif. Pub. Zool. 39, 303 310. ref . More recently, Winklbauer and Sch rfeld 1999 described the internal movements in more detail using pregastrular explants of Xenopus laevis ref name winklbauer . Gastrulation in amphibians is initiated by formation of bottle cells at the dorsal marginal zone, followed by involution of prospective mesodermal cells ref Gerhart, J., and Keller, R., 1986. Region Specific Cell Activities in Amphibian Gastrulation. Annu. Rev. Cell Biol. 2 201 229. ref . The mesoderm and endoderm then migrate animally along the blastocoel roof, driven in part by movement of the vegetal endoderm cells. In Xenopus embryos in which the blastocoel roof is removed prior to gastrulation, the movement of vegetal cells toward the blastocoel and their intercalation into the blastocoel floor causes the floor to spread, pushing the dorsal edge downward ref name winklbauer . In the context of the embryo, active vegetal rotation, together with epiboly of the animal cap ectodermal cells, appears to bring the vegetal mesendoderm into contact with the blastocoel roof ref name winklbauer ref Papan, C., Boulat, B., Velan, S.S., Fraser, S.E., and Jacobs, R.E., 2007. Formation of the dorsal marginal zone in Xenopus laevis analyzed by time lapse microscopic magnetic ... more details
A cell type is a distinct morphological or functional form of cell biology cell . When a cell switches state from one cell type to another, it undergoes cellular differentiation . A list of distinct cell types in the adult human body may include several hundred distinct types. ref Molecular Biology of the Cell , Fourth Edition, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter ref ref http www.copewithcytokines.de cope.cgi?key cell 20types ines.de cope.cgi COPE database ref References Reflist Human cell types derived primarily from ectoderm Human cell types derived primarily from endoderm Germ layer Category Developmental biology de Zelltyp many types of cells are present in human body a cell type is a distinct monmorphological or functional form of cell. When a cell switches state from one cell type to another, it undergoes cellular differentiation. A complete list of distinct cell types in the adult human body may include about 210 distinct types. ... more details
Encyclopedia
top
