in parallel to the yolk sac involution size of the nuclei , nucleoli , cytoplasm in the cytotrophoblast elements and the simplast nuclei of the labyrinth bars in the allantoic placenta increase , while the size of the nuclei in the amniotic and exocelomic epithelium of the amnion and of the exocelomic epithelium of the visceral leaf in the yolk sac decreases .
C0007609
nucleoli
C0007610
nuclei