Question

What are the changes in the oogonia during the transition of a primary follicle to Graafian follicle?

Answer 1

The germinal epthelial cells repeatedly divide until many diploid oogonia are formed. The layer of granulosa cells and then called the primary follicle. The primary follicles get surrounded by more layers of granulosa cells and called secondary by a fluid-filled cavity called antrum.

The primary oocyte within the tertiary follicle undergoes melotic division to become a secondary oocyte and a first polar body (haploid). The tertiary follicle further changes into the mature follicle or Graafian follicle that ruptures to release the secondary oocyte (ovum) from the ovary by the process called ovulation.