| Blastocyst | ||
|---|---|---|
 |
||
| Carnegie stage | 3 | |
| Days | 5 | |
| MeSH | Blastocyst | |
| Dorlands/Elsevier | b_14/12187695 | |
The blastocyst is the structure formed in early embryogenesis, after the formation of the blastocoel, but before implantation. In Embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the Vertebrate Embryo. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group Embryogenesis is the process by which the Embryo is formed and develops A blastocoel(e or blastocele (also called blastocyst cavity, cleavage cavity or segmentation cavity) is the Fluid -filled central Implantation is an event that occurs early in pregnancy in which the Embryo adheres to the wall of Uterus.
It possesses an inner cell mass, or embryoblast which subsequently forms the embryo, and an outer cell mass, or trophoblast which forms the placenta. In early Embryogenesis of most Eutherian mammals the inner cell mass (abbreviated ICM and also known as the embryoblast or Pluriblast Trophoblasts (from Greek threphein: to feed and blastos: germinator are cells forming the outer layer of a Blastocyst, which provide nutrients The placenta is an Ephemeral organ present in placental Vertebrates, such as Eutherial Mammals and Sharks during Gestation The human blastocyst arises after compaction and comprises 70-100 cells. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called It is preceded by a zygote, the fertilized egg cell, and succeeded by an embryo. For other meanings see Zygote (disambiguation. A zygote (from Greek ζυγωτός zugōtos "joined" or "yoked" An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular
Blastocyst formation begins at day 5[1]. Differential expression of cells in the morula is thought to be the cause of the lineage divergence of different cell types. For example, Oct 3 and Oct4 transcription factors are restricted to the ICM, whereas Cdx2 is restricted to the trophoblast. This differential transcription factor expression is likely to be the result of positional effect - cells in the middle of the preceding zygote are in a different environment to those on the outside, thus causing differential expression.
Formation of the blastocyst
The blastocyst consists of two primary cell lines:
- the inner cell mass, also known as the "embryoblast"
- the trophoblast
The former is the source of embryonic stem cells and gives rise to all later structures of the adult organism. In early Embryogenesis of most Eutherian mammals the inner cell mass (abbreviated ICM and also known as the embryoblast or Pluriblast Trophoblasts (from Greek threphein: to feed and blastos: germinator are cells forming the outer layer of a Blastocyst, which provide nutrients Embryonic stem cells (ES cells are Stem cells derived from the inner cell mass of an early stage Embryo known as a Blastocyst. The latter combines with the maternal endometrium to form the placenta in eutherian mammals. The endometrium is the inner membrane of the Mammalian Uterus. The placenta is an Ephemeral organ present in placental Vertebrates, such as Eutherial Mammals and Sharks during Gestation See also Evolution of mammals Eutheria ("true beast" are a group of Mammals consisting of Placental mammals plus all extinct Mammals
References
- ^ UNSW Embryology- Week 1. Retrieved on 2007-12-30. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1460 - Wars of the Roses: Battle of Wakefield. 1816 - The Treaty of St
External links
This article was originally based on an entry from a public domain edition of Gray's Anatomy. Prenatal development is the process in which an embryo or fetus (or foetus) gestates during Pregnancy, from fertilization The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone Henry Gray's Anatomy of the Human Body (or Gray's Anatomy as it has commonly been shortened is an English-language Human anatomy Textbook As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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