Infobox Embryology Name Blastocoele Latin GraySubject GrayPage Image Blastocyst.gif Caption Blastocyst Image2 Blastocyst English.svg Caption2 Blastocyst with an inner cell mass and trophoblast . System CarnegieStage 3 Days 5 Precursor morula GivesRiseTo primitive yolk sac MeshName MeshNumber DorlandsPre b 14 DorlandsSuf 12187664 A blastocoel e or blastocele also called blastocyst cavity , ref cite web url http www.embryology.ch anglais iperiodembry carnegie02.html title The Carnegie stages accessdate 2007 10 13 format work ref cleavage cavity or segmentation cavity is the fluid filled central region of a blastocyst . A blastocoele forms during embryogenesis when a zygote a fertilized ovum divides into many cells through mitosis . The adjective adjectival of blastocoel e is blastocoelic . A blastocoel can be described as the first cell cavity formed as the embryo enlarges. It is essential for later gastrulation . References references See also Embryo Extraembryonic and fetal membranes Category Developmental biology developmental biology stub cs Blastocoel de Blastocoel es Blastocele fr Blastoc le it Blastocele ja pl Blastocel pt Blastoc lio ru tr Blastos l ... more details
Infobox Embryology Name Blastocyst Latin blastocystis GraySubject GrayPage Image Blastocyst English.svg Caption Image2 Caption2 System CarnegieStage 3 Days 8 Precursor Morula GivesRiseTo Gastrula , Inner cell mass MeshName Blastocyst MeshNumber A16.254.085 Code Terminologia Embryologica TE E2.0.1.2.0.0.12 File Blastocyst.JPG thumb A human blastocyst, 5 days after fertilization. File PorcineBlastocyst.jpg thumb A pig blastocyst. The bar is 0.1 mm. for the single celled parasite Blastocystis Nofootnotes article date April 2012 The blastocyst is a structure formed in the early embryogenesis of mammal s, after the formation of the morula . It is a specifically mammalian example of a blastula . citation needed date January 2011 It possesses an inner cell mass ICM , or inner cell mass embryoblast , which subsequently forms the embryo , and an outer layer of cells, or trophoblast , which later forms the placenta . The trophoblast surrounds the inner cell mass and a fluid filled blastocyst cavity known as the blastocoele or the blastocystic cavity. The human blastocyst comprises 70 100 Cell biology cells . Blastocyst formation begins at day 5 after fertilization in humans, when the blastocoele opens up in the morula, a process known as hatching. citation needed date January 2011 Parts of the blastocyst The blastocyst consists of two primary cell types the inner cell mass , also known as the embryoblast this part of the embryo is used in stem cell research the trophoblast , a layer of cells surrounding the inner cell mass and the blastocyst cavity blastocoele The former is the source of embryonic stem cells and gives rise to all later structures of the adult organism. The latter combines with the maternal endometrium to form the placenta in eutherian mammals. Formation of the blastocyst The morula is a solid ball of about 16 undifferentiated, spherical cells. As cell division continues in the morula, the blastomeres change their shape and tightly align themselves against eac ... more details
Infobox Embryology Name PAGENAME Latin epiblastus GraySubject GrayPage Image Gray21.png Caption Section through the embryo. Epiblast visible but not labeled. Image2 Cell differentiation gastrula.PNG Caption2 Cell differentiation System CarnegieStage 3 Days 8 Precursor inner cell mass GivesRiseTo ectoderm , mesoderm , endoderm MeshName MeshNumber Code Terminologia Embryologica TE E5.0.2.2.1.0.1 In amniote animal embryology , the epiblast is a tissue type derived either from the blastodisc in reptiles incl. birds or the inner cell mass in mammal s. It lies above the hypoblast . Mammals In mammalian embryogenesis , the columnar cells of the epiblast are adjacent to the trophoblast , while the cuboidal cells of the hypoblast are closer to the blastocoele . The epiblast, whilst referred to as the primary ectoderm, differentiates to form all three layers of the trilaminar germ disc in a process called gastrulation . Epiblast diversity Human epiblast is disc shaped as opposed to the mouse epiblast which is cup shaped. See also Embryogenesis Mammalian embryogenesis Hypoblast 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 developmental biology stub Embryology Category Embryology de Epiblast es Epiblasto it Epiblasto pl Epiblast pt Epiblasto ru zh ... more details
Image Trocofora.svg right thumb The anatomy of a trochophore br A episphere br B hyposphere br 1 ganglion ganglia br 2 apical tuft br 3 prototroch br 4 metatroch br 5 nephridium br 6 anus br 7 proto nephridium nephridia br 8 gastrointestinal tract br 9 buccal opening br 10 blastocoele Image Pomatoceros lamarckii trochophore.jpg thumb Bright field microscope image of trochophore of annelid Pomatoceros lamarckii family Serpulidae A trochophore IPAc en icon t r k f r also spelled trocophore is a type of free swimming plankton ic marine larva with several bands of cilia . By moving their cilia rapidly, a water eddy is created. In this way they control the direction of their movement. Additionally, in this way they bring their food closer, in order to capture it more easily. Occurrence Trochophores exist as a larval form within the trochozoan clade, which include the entoprocta entoprocts , mollusc s, annelid s, echiura ns, sipuncula ns and nemertea ns. Together, these phyla make up part of the Lophotrochozoa it is possible that trochophore larvae were present in the life cycle of the group s common ancestor. Feeding habits Trochophore larvae are often planktotrophic that is, they feed on plankton. Life cycle Image Polyplacophora ontogeny.jpg left thumb 300px Ontogeny of the Polyplacophora First image shows the trochophore, second shows the stadium in metamorphosis, third is a juvenile Scanning electron microscope SEM Image of development of the annelid Pomatoceros lamarckii family Serpulidae showing the trochophore in images D F. br D early trochophore br E complete trochophore br F late trochophore br G metatrochophore Image Haliotis asinina trochophore.jpg thumb 9 hour old trochophore of the marine gastropod Haliotis asinina br sf gastropod shell shell field commons category Trochophore External links Category Developmental biology invertebrate stub developmental biology stub az Trochozoa ca Troc fora cs Trochofora de Trochophora et Trohhofoor es Troc fora fr ... more details
Unreferenced date January 2007 In embryology , Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo . The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain extent between embryos. It only covers the first 60 days of development at that point the term embryo is usually replaced with the term fetus . It was based on work by Streeter 1942 and O Rahilly and M ller 1987 . The name Carnegie stages comes from the Carnegie Institution for Science Carnegie Institution of Washington . While the Carnegie stages provide a universal system for staging and comparing the embryonic development of most vertebrates, other systems are occasionally used for the common model organism s in developmental biology , such as the Hamburger Hamilton stages in the chicken chick . Stages Days are approximate, and reflect the days since the last ovulation before pregnancy Postovulatory age . Stage 1 1 days fertilization polar bodies Stage 2 2 3 days Cleavage embryo cleavage morula Human embryogenesis Cleavage compaction Stage 3 4 5 days blastocyst and blastocoele trophoblast and embryoblast Stage 4 6 days syncytiotrophoblast cytotrophoblast amniotic ectoderm Stage 5 a c 7 12 days Implantation human embryo implantation embryonic disk bilaminar disk bilaminar germ disk primary yolk sac amniotic cavity Stage 6 ca 17 days primitive streak primitive groove chorionic villi secondary yolk sac Stage 7 ca 19 days gastrulation neural plate start of hematopoiesis notochord Stage 8 ca 23 days primitive pit Stage 9 ca 25 days neural groove neural folds septum transversum placode early heart Stage 10 ca 28 days pharyngeal arches 1 and 2 cardiac loop intermediate mesoderm Stage 11 ca 29 days sinus venosus mesonephric duct Stage 12 ca 30 days upper limb buds Stage 13 ca 32 days septum primum foramen primum Stage ... more details
Infobox Embryology Name Inner cell mass Latin embryoblastus massa cellularis interna pluriblastus senior GraySubject 6 GrayPage 46 Image Blastocyst English.svg Caption Blastocyst with an inner cell mass and trophoblast . Image2 Caption2 System CarnegieStage 3 Days 6 Precursor blastocyst GivesRiseTo epiblast , hypoblast MeshName MeshNumber Code Terminologia Embryologica TE E6.0.1.1.2.0.4 In early embryogenesis of most eutherian mammals, the inner cell mass abbreviated ICM and also known as the embryoblast or pluriblast , the latter term being applicable to all mammals is the mass of cells inside the primordial embryo that will eventually give rise to the definitive structures of the fetus. This structure forms in the earliest steps of development, before Implantation human embryo implantation into the endometrium of the uterus has occurred. The ICM lies within the blastocoele more correctly termed blastocyst cavity, as it is not strictly homologous to the blastocoele of anamniotes anamniote vertebrates and is entirely surrounded by the single layer of cells called trophoblast . Further development The physical and functional separation of the inner cell mass from the trophectoderm TE is a special feature of mammalian development and is the first cell lineage specification in these embryos. Following fertilization in the oviduct, the mammalian embryo undergoes a relatively slow round of cleavages to produce an eight cell morula. Each cell of the morula, called a blastomere, increases surface contact with its neighbors in a process called compaction. This results in a polarization of the cells within the morula, and further cleavage yields a blastocyst of roughly 32 cells. ref name Wolpert Wolpert, Lewis. Principles of Development Third Edition. 2007. Oxford University Press. ref Generally, about 12 internal cells comprise the new inner cell mass and 20 24 cells comprise the surrounding trophectoderm,.. ref name Marikawa Marikawa, Yusuke, et al. Establishment of Trophe ... more details
refimprove date March 2012 for pregnancy in humans pregnancy Image PregnantLioness.jpg thumb right 300px A pregnant lion ess. In mammal s, pregnancy is the period of reproduction during which a female carries one or more live offspring from Implantation human embryo implantation in the uterus through gestation . It begins when a fertilisation fertilized zygote implants in the female s uterus and ends once it leaves the uterus . Fertilization and implantation A male and female sexual intercourse copulate , the male insemination inseminating the female. The spermatozoon fertilisation fertilize s an ovum or various ova in the uterus or fallopian tube s, and this results in one or multiple zygote s. Sometimes, a zygote can be created by humans outside of the animal s body in the artificial process of in vitro fertilisation in vitro fertilization . After fertilization, the newly formed zygote then begins to divide through meiosis , forming an embryo , which implants in the female s endometrium . At this time, the embryo usually consists of 50 cells. Development File Elefetusus.jpg thumb left 500px 14 fetuses showing stages of embryo development in the African elephant After implantation A blastocoele is a small cavity on the center of the embryo, and the developing embryonary cells will grow around it. Then, a flat layer cell forms on the exterior of this cavity, and the zona pellucida , the blastocyst s barrier, remains the same size as before. Cells grow increasingly smaller to fit in. This new structure with a cavity in the center and the developing cells around it is known as a blastocyst . The presence of the blastocyst means that two types of cells are forming, an inner cell mass growing on the interior of the blastocele and cells growing on the exterior of it. In 24 to 48 hours, the zona pellucida breaches. The cells on the exterior of the blastocyst begin excreting an enzyme which erodes epithelium epithelial uterine lining and creates a site for implantation. Pl ... more details
Other uses Expert subject biology documentation date November 2008 Infobox embryology Name Embryo Latin GraySubject GrayPage Image Wrinkledfrog embryos.jpg Caption Embryos and one tadpole of the wrinkled frog Rana rugosa Image2 Caption2 MeshName MeshNumber Code Terminologia Embryologica TE E1.0.2.6.4.0.5 An embryo irregularly from Greek language Greek lang grc , plural lang grc , lit. that which grows, from en in bryein , to swell, be full the proper Latinate form would be embryum is a multicellular organism multicellular ploidy diploid eukaryote in its earliest stage of Developmental biology development , from the time of first cell division until birth , Egg biology hatching , or germination . In humans, it is called an embryo until about eight weeks after fertilisation fertilization i.e. ten weeks Gestational age Last Menstrual Period or LMP , and from then it is instead called a fetus . The development of the embryo is called embryogenesis . In organism s that sex reproduce sexually , once a spermatid sperm fertilizes an ovum egg cell , the result is a cell biology cell called the zygote , which possesses half the DNA of each of its two parents. In plant s, animal s, and some protist s, the zygote will begin to divide by mitosis to produce a multicellular organism. The result of this process is an embryo. Animal embryos In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula , gastrulation gastrula , and organogenesis . The blastula stage typically features a fluid filled cavity, the blastocoele blastocoel , surrounded by a sphere or sheet of cells, also called blastomere s. The embryo of a eutheria placental mammal is defined as the organism between the first cell division division of the zygote a fertilized ovum until it becomes a fetus . An ovum is fertilized in a fallopian tube through which it travels into the uterus. In humans, the embryo is defined as the product of conception after ... more details
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