Question

Explain Oogenesis with diagram.

Answer 1

1. Oogenesis: It is the process of producing a haploid female gamete, such as an egg or an ovum, from a diploid germinal epithelium. It depicts the three phases listed below.
2. Multiplication phase: PGCs (2n) of the ovary undergo recurrent mitotic division at this stage, resulting in millions of oogonial cells (2n). This process is accomplished in human female embryos during the embryonic stage.
3. Growth phase: Some oogonia cease dividing and begin to grow in size, forming primary oocytes (2n).
4. Maturation phase: Oogenesis occurs before to the birth of a female baby. The maturation phase of primordial oocytes (2n) comprises meiotic division (Meiosis I and Meiosis II).
5. Meiosis I occurs in diploid primary oocytes, resulting in the formation of two haploid daughter cells. However, due to unequal cytoplasmic division, one of the two daughter cells formed is a giant cell known as the secondary oocyte (n), while the other is a small cell known as the first polar body (n). Only up to metaphase II does the secondary oocyte (n) go through meiosis II.
6. At this point, its division has been halted or arrested. The graafian follicle and ovary shed the secondary oocyte. Only the admission of the sperm will result in the conclusion of meiosis II. This division also produces two unequal daughter cells: the giant cell is the ovum (n), while the little cell is the 2nd polar body (n). The ovum) that has developed serves as the female gamete that is ready for fertilisation.