Oogenesis:

The process of formation of mature female gamete in the ovary of females is called oogenesis.

 

Processs of Oogenesis:

1) Oogonia are diploid cells formed at embryonic stage. No, more oogonia are added to female overy after birth.

2) After entering Prophase -1, they get arrested here, and called primary oocyte.

3) Each primary oocyte then gets surrounded by a layer of granulosa cells and is called the primary follicle.

4) The primary follicles get surrounded by more layers of granulosa cells and a new theca and are called secondary follicles.
5) The secondary follicle soon transforms into a tertiary follicle which is characterised by a fluid filled cavity called antrum.

6) The theca layer is organised into an inner theca interna and an outer theca externa. It is important to draw your attention that it is at this stage that the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division.

7) It is an unequal division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body.

8) The tertiary follicle further changes into the mature follicle or Graafian follicle. The secondary oocyte forms a new membrane called zona pellucid surrounding it. The Graafian follicle now ruptures to release the secondary oocyte(Ovary), and this process is called Ovulation.

Structure of Ovary and follicular maturation during ovulation:

Hormonal control of Oogenesis: