Fig. 6

Ovarian ultrastructure at the MAT stage of development; a thick and irregular chorion, still with the presence of microvilli (black arrow). Note some endocytic vesicles (white arrow); b regular chorion, with two layers of different electron-dense material (1 and 2). Follicular cell with less electron-dense basal lamina and cytoplasm with mitochondria; c endocytic-coated vesicle; d, e cytoplasm filled with mature yolk vesicles, among them, small areas with immature yolk, lipid droplets and glycogen α (black arrow); f immature and mature yolk vesicles surrounded by the membrane unit (black arrows). 1. less electron-dense chorion layer, 2. more electron-dense chorion layer, C chorion, EV endocytic vesicle, FC follicular cell, L basal lamina, LI lipid, M mitochondria, MV microvilli, Y1 immature yolk vesicle, Y2 mature yolk vesicle