Explain how the germinal epithelium gives rise to primordial follicles?

During the fetal period, the count of germ cells in the female organism is subject to large variations. These arise due to the fact that the phases of proliferation and decomposition of oocytes described below take place partially stepwise and partially in parallel.

Phase A:
Primordial germ cells grow, proliferate and become sheathed with coelomic epithelial cells. Gonadal cords arise; 6th to 8th week.

Phase B:
Spurt of growth: cellular clones of the oogonia are formed, whereby the cells remain connected with each other through cellular bridges; 9th to the 22nd week.

Phase C:
The oogonia become primary oocytes that enter the prophase of the first meiosis; 12th to the 25th week.

Phase D:
The primary oocytes become arrested in the dictyotene stage of the prophase: the primordial follicles are engendered; 16th to the 29th week.

Phase E:
At around the 14th week a quantitatively increased decline in the number of germ cells commences as well as atresia in all of the follicle stages.