Question

What are oogonia cells?

Answer 1

Hint: Gametogenesis is the process of formation and differentiation of haploid gamete (i.e.sperms and ova) from diploid primary germ cells, gametogonia present in primary sex organs called gonads. Gametogenesis is of two types: 1. Spermatogenesis and 2. Oogenesis. Oogenesis is the formation of haploid gametes called ova.

Complete solution:
Oogonia are diploid egg mother cells in the ovary of female organisms, these cells have a large nucleus and small amount of cytoplasm, they are formed from primitive germ cells, it gives rise to ova, this process is called oogenesis.

In human females, there are about 1700 primary germ cells in the undifferentiated female gonads at one month of foetal development. These cells proliferate to form about 600,000 oogonia at two months of gestation period and by 5th month of gestation, the ovaries contain over 7 million oogonia.
No oogonia are formed or added after birth.
Scattered ovarian follicles are embedded in the stroma of cortex.
An ovarian follicle consists of an oocyte, surrounded by one or more layers of follicular cells, the granulosa cells, which are derived from the germinal epithelium lining the ovary. These oogonial cells start dividing and enter into prophase-1 of the meiotic division, and get temporarily arrested at this stage called primary oocytes. A layer of granulosa cells surrounding each primary oocyte; at this stage they are called the primary follicle.

Note:
A large number of these follicles degenerate from birth to puberty, degeneration of ovarian follicles is called follicular atresia and their disposal is done by phagocytes. Therefore, by the time puberty is reached there are only 60,000 to 80,000 primary follicles left in each ovary, and a primary follicle begins to mature with each ovarian cycle.