Embryonic disc

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

Embryonic disc
Section through embryonic disk of Vespertilio murinus.
Surface view of embryo of a rabbit. (After Kölliker.) arg. Embryonic disk. pr. Primitive streak.
Carnegie stage4
Latindiscus embryonicus
Anatomical terminology

In humans, it is the stage of development that occurs after implantation and prior to the embryonic folding (e.g. 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.


This article incorporates text in the public domain from page 47 of the 20th edition of Gray's Anatomy (1918)

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