Secondary Follicle

The single layer of follicular cells found in the primary follicle divide by mitosis giving rise to multiple layers of cells. Once the follicle has multiple layers of follicular cells, those cells become known as granulosa cells. It is at this point that the follicle is known as a secondary follicle.

A secondary follicle consists of:

1. A primary oocyte surrounded by the zona pellucida

2. Two or more layers of granulosa cells

Figure 1: Illustration of secondary follicles inside an ovary.