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
Orphan date February 2009 A blastospore is an asexual reproduction asexual fungal spore produced by budding . Produced by fungi within the phylum Glomeromycota and others. During gastrulation , it leads to the formation of the archenteron . It is also known as blastoconidium plural blastoconidia. Ex Candida fungus stub References cite web title blastospore definition Dictionary MSN Encarta BOT GENERATED TITLE url http encarta.msn.com dictionary 1861591096 blastospore.html work archiveurl http www.webcitation.org 5kwQA3b2I archivedate 2009 10 31 deadurl yes http www.bartelby.com 61 65 B0316500.html Category Fungi it Blastospora ... more details
wiktionary Streak or streaking may refer to Streaking , running naked in a public place Streaking microbiology , a method of purifying micro organisms Streak mineralogy , the color left by a mineral dragged across a rough surface Streak moth , in the family Geometridae Streak film , a 2008 film Winning streak sports , consecutive wins in sport or gambling Losing streak sports Dell Streak , tablet computer by Dell Streak camera , device to measure short optical pulses The Streak , a 1974 record by Ray Stevens Archenteron , an indentation on a blastula Heath Streak , former Zimbabwe cricket team captain Aero Flight Streak Streak late 1940s single engine civilian aircraft See also Streaker disambiguation disambig ja ... 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
Infobox Embryology GraySubject 6 GrayPage 47 DorlandsPre b 14 DorlandsSuf 12188030 A blastopore is an opening into the archenteron during the embryonic stages of an organism. The Embryological origins of the mouth and anus distinction between protostome s and deuterostome s is based on the direction in which the mouth stoma develops in relation to the blastopore. Protostome derives from the Greek word protostoma meaning first mouth whereas Deuterostome s etymology is second mouth from the words second and mouth . The major distinctions between deuterostomes and protostomes are found in embryonic development Mouth anus In protostome development, the first opening in development, the blastopore, becomes the animal s mouth . In deuterostome development, the blastopore becomes the animal s anus . Cleavage embryo Cleavage Protostomes have what is known as spiral cleavage which is determinate , this meaning that the fate of the cells is determined as they are formed. Deuterostomes have what is known as radial cleavage that is indeterminate . See also Blastula External links eMedicineDictionary Blastopore developmental biology stub Embryology Category Developmental biology ca Blast por cs Prvo sta de Urmund es Blastoporo fr Blastopore it Blastoporo ja pl Prag ba pt Blast poro ru sr uk ... more details
Infobox Embryology Name PAGENAME Latin 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 archenteron 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 cells of the primitive knot secrete many cellular signals essential for gastrulation including Fibroblast Growth Factor s, Sonic hedgehog , and retinoic acid . Cilia beating within the knot cause differential buildup of secreted factors in the nodal cavity, leading to development of the right left axis in the embryo. References references External links http www.nature.com ncb journal v3 n6 fig tab ncb0601 e138 F1.html Overview at nature.com http www.biochem.northwestern.edu holmgren Glossary De ... more details
Infobox Embryology Name PAGENAME Latin GraySubject 6 GrayPage 49 Image Endoderm2.png Caption Organs derived from endoderm. Image2 Gray10.png Caption2 Blastodermic vesicle of Vespertilio murinus . Endoderm labeled as entoderm . System CarnegieStage Days 16 Precursor hypoblast GivesRiseTo splanchnopleure MeshName Endoderm MeshNumber A16.254.425.407 DorlandsPre DorlandsSuf Endoderm , sometimes called Entoderm is one of the germ layer s formed during animal embryogenesis . Cells migrating inward along the archenteron form the inner layer of the gastrula , which develops into the endoderm. Citation needed date January 2011 The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems. Citation needed date January 2011 Production 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 s containing this layer produce the adjacent product. ref Gastrointestinal tract . the entire alimentary canal except part of the mouth , pharynx and the terminal part of the rectum which are lined by involutions of the ectoderm , the lining cells of all the glands which open into the digestive 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 Liver and pancreas cells are believed to derive from a common precursor. ref name pmid11532400 cite journal author Zaret KS title Hepatocyte differentiation from the endoderm and beyond journal Curr. Opin. Genet. Dev. volume 11 issue 5 pages 568 74 year 2001 month October pmid 11532400 doi ... more details
forms as a blind pouch called the archenteron . In Protostomes the coleom forms by a process known as schizocoely. The archenteron initially forms, and the mesoderm splits into two layers the first attaches ... mesoderm buds from the walls of the archenteron and hollows to become the coelomic cavities. Origins ... more details
and organs. citation needed date January 2011 The appearance of the archenteron marks the onset of gastrulation ... layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner ... more details
Histogenesis is the formation of different Biological tissue tissues from undifferentiated cell biology cells . ref cite encyclopedia title histogenesis definition Dictionary MSN Encarta url http www.encarta.msn.com dictionary Histogenesis.html work archiveurl http www.webcitation.org 5kwqdxnnP archivedate 2009 10 31 deadurl yes ref These cells are constituents of three primary germ layer s, the endoderm , mesoderm , and ectoderm . The science of the microscopic structures of the tissues formed within histogenesis is termed histology . Germ layers File Gastrulation.png thumb 300px Gastrulation of a diploblasty diploblast The formation of germ layers from a 1 blastula to a 2 gastrula . Some of the ectoderm cells orange move inward forming the endoderm red . main Germ layer A germ layer is a collection of cell biology cell s, formed during animal and mammalian embryogenesis . Germ layers are typically pronounced within vertebrate organisms however, animal s or mammals more complex than sea sponge sponge s eumetazoa ns and wikispecies agnotozoa agnotozoans produce two or three primary tissue layers. Animals with symmetry biology Radial symmetry radial symmetry , such as cnidaria ns, produce two layers, called the ectoderm and endoderm . Therefore, they are diploblastic . Animals with symmetry biology Bilateral symmetry bilateral symmetry produce a third layer in between called mesoderm , making them triploblastic . Germ layers will eventually give rise to all of an animal s or mammal 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. Mesoderm main Mesoderm The mesoderm germ layer forms in the embryo s of animal s and mammal s ... more details
This article needs to be clarified and may contain errors. File Protovsdeuterostomes.svg thumb The embryological origin of the mouth and anus is an important characteristic, and forms the morphological basis for separating bilateria n animals into two clade natural grouping s the protostome s and deuterostome s. In animals at least as complex as an earthworm , a dent forms in one side of the early, sphere spheroidal embryo . This dent, the blastopore , deepens to become the archenteron , the first phase in the growth of the Gut zoology gut . In deuterostome s including humans , the original dent becomes the anus, while the gut eventually tunnels through the embryo until it reaches the other side, forming an opening that becomes the mouth. ref name Hejnol2008 It was originally thought that the blastopore of the protostome s formed the mouth, and the anus was formed second when the gut tunneled through the embryo. More recent research has shown that our understanding of protostome mouth formation is somewhat less secure than we had thought. The edges of the dent appear to move together and close up in the middle, leaving openings at the ends which become the mouth and anus. ref cite journal title Evolution of the bilaterian larval foregut author Arendt, D. Technau, U. Wittbrodt, J. journal Nature volume 409 pages 81 85 date 4 January 2001 issue 6816 doi 10.1038 35051075 pmid 11343117 ref However, this idea has been challenged, because the Acoelomorpha , which form a sister group to the rest of the bilaterian animals, have a single mouth which leads into a blind gut with no anus . The genes employed in the embryonic construction of the flatworm mouth are the same as those expressed around the protostomes , which suggests that the two structures are equivalent, and that the older ideas about protostome mouth formation were correct. ref name Hejnol2008 cite journal doi 10.1038 nature07309 year 2008 month Nov author Hejnol, A Martindale, M.q. title Acoel development indic ... more details
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