Idealized amniote embryo. Legend: a=embryo, b=yolk, c=allantois, d=amnion, e=chorion
<a href="//commons.wikimedia.org/wiki/User:Petter_B%C3%B8ckman" title="User:Petter Bøckman">Petter Bøckman</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>