Fig. 16. Photomicrograph of an early tertiary follicle (0.4 mm in diameter) at the cavitation of early antrum stage. ZP, zona pellucida; GC, granulosa cells; BL, basal lamina; TI, theca interna; TE, theca externa; arrowheads, granulosa mitosis. (From Bloom W, Fawcett DW: A Textbook of Histology. Philadelphia: WB Saunders, 1975, with permission from Arnold Ltd.)