ClipArt ETC
"Diagram of foetal membranes. E., Embryo; H., gut lined by hypoblast, dotted-- the dark is mesoblast; UV., umbilical vesicle or yolk-sac; AC., amniotic cavity; am., amnion proper; sz., subzonal membrane; ALC., allantoic cavity; al., allantois; zp., may be here taken to represent the early epiblastic trophoblast. The figure does not show that the amnion folds consist of both epiblast and mesoblast." -Thomson, 1916

Mammal Fetus

"Diagram of foetal membranes. E., Embryo; H., gut lined by hypoblast, dotted-- the dark is mesoblast;…