Zoology - Human Reproduction Question with Solution | TestHub

Primary follicles are converted to secondary follicles by getting surrounded by a few more layers of granulosa cells and a new theca. This is an undifferentiated theca. Following changes occur in the secondary follicle after which it is immediately converted to tertiary follicle:

A. Development of a fluid-filled cavity called - Antrum.
B. Differentiation of Theca layer into - Theca interna (inner) and Theca externa (outer).