Antral follicle and atretic follicle, plastic embedded section. The follicle has developed a fluid-filled antrum within the granulosa layer. Thus, it qualifies a secondary follicle. This antrum is filled with follicular fluid. The zona pellucida is stained bright pink. The atretic follicle shows a loss of the oocyte, collapse of the follicular structure, proliferation of theca interna cells and a centrally located remnant of the zona pellucida, which appears as a collapsed light pink band.