Figure 9. A typical healthy secondary follicle. It contains a fully grown oocyte surrounded by the zona pellucida, 5 to 8 layers of granulosa cells, a basal lamina, a theca interna and externa with numerous blood vessels. (Bloom W, Fawcett DW In A Textbook of Histology. WB Saunders Company, Philadelphia 1975. With permission from Arnold.)