|Description:||As the follicle develops, the oocyte becomes larger. The follicular
cells proliferate and the oocyte is surrounded by stratified polyhedral
cells called granulosa cells. At the interface between the oocyte and
the granulosa cells a glycoprotein layer, the zona pellucida, appears.
Tiny microvilli (not discernible here) from the oocyte penetrate the
zona and form gap junctions with the granulosa cells. Through these
contacts nutrients, hormones and signal molecules can be passed. The
nucleus of the oocyte is out of the plane of section. As the follicle
becomes larger, little fluid-filled spaces appear between the granulosa
cells. The granulosa cells are enclosed by a distinct basal lamina. The
stromal cells immediately around the follicle differentiate into plump
theca cells. Although blood vessels may be found among the thecal
cells, they do not penetrate the basal lamina. PK4892-25.Original mag.
80x. H&E. Secondary follicle. Cortex. Ovary. Female Reproductive