Figure 10. Photomicrograph of an early tertiary follicle 0.4 mm in diameter at the cavitation or early antrum stage. Oocyte (ooc); zona pellucida (ZP); granulosa cells (GC); basal lamina (BL); theca interna (TI); theca externa (TE); granulosa mitosis (arrowheads). (Revised from Bloom W, Fawcett DW In A Textbook of Histology. Philadelphia, WB Saunders Company, Philadelphia 1975. With permission from Arnold.)