Embryonic disk
Section through embryonic disk of Vespertilio murinus.
Surface view of embryo of a rabbit. (After Kölliker.) arg. Embryonic disk. pr. Primitive streak.
Gray's	subject #6 47
Carnegie stage	4

The floor of the amniotic cavity is formed by the embryonic disk (or embryonic disc) composed of a layer of prismatic cells, the embryonic ectoderm, derived from the inner cell-mass and lying in apposition with the endoderm.

In humans, it is the stage of development that occurs after implantation and prior to the embryonic folding (eg. seen between about day 14 to day 21 post fertilization). It is derived from the epiblast layer, which lies between the hypoblast layer and the amnion. The epiblast layer is derived from the inner cell mass. Through the process of gastrulation, the bilaminar embryonic disc becomes trilaminar. The notochord forms thereafter. Through the process of neurulation, the notochord induces the formation of the neural tube in the embryonic disc.

[edit] External links

• Anatomy at MUN embryo/emb2
• Diagram at manchester.ac.uk

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e Developmental biology > Human embryogenesis (development of embryo) and development of fetus First three weeks Week 1 Fertilization · Egg activation · Zygote · Cleavage · Morula · Blastula (Blastomere) · Blastocyst · Inner cell mass Week 2 (Bilaminar) Hypoblast · Epiblast Week 3 (Trilaminar) Germ layers Archenteron/Primitive streak (Primitive pit, Primitive knot/Blastopore, Primitive groove) · Gastrula/Gastrulation · Regional specification Ectoderm Surface ectoderm · Neuroectoderm · Somatopleure · Neurulation · Neural crest Endoderm Splanchnopleure Mesoderm Chorda- · Paraxial (Somite/Somitomere/Sclerotome/Myotome/Dermatome) · Intermediate · Lateral plate (Intraembryonic coelom, Splanchnopleure/Somatopleure) Extraembryonic/ uterus Trophoblast (Cytotrophoblast, Syncytiotrophoblast) Blastocoele · Yolk sack/exocoelomic cavity · Heuser's membrane · Extraembryonic coelom · Vitelline duct Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) · Allantois Placenta · Decidua (Decidual cells) · Chorionic villi/Intervillous space · Gestational sac (Amnion/Amniotic sac/Amniotic cavity, Chorion) Histogenesis Programmed cell death (Apoptosis) · Stem cells · Germ line development Organogenesis Limb development: Limb bud · Apical ectodermal ridge/AER other structures: Eye development · Cutaneous structure development · Heart development · Development of the urinary and reproductive organs (Some dates are approximate—see Carnegie stages and a timeline.)