Question

Oogonia are
(a) Constant in number before the birth and added after birth
(b) Constant in number and never be added after the birth
(c) Constant in number before birth without division
(d) Never be constant in number both before and after birth

Answer 1

Hint: Oogonia is formed by the oogenesis process which is initiated during the embryonic development stage when the formation of nearly 2 million Oogonia formed in the fetal ovary and they won't undergo any cell division.

Complete answer:
Mature female gamete formation is done by the process called oogenesis. During the embryonic development stage, oogenesis is initiated when two million gamete mother cells called oogonia are formed within the ovary of the fetus and they do not multiply thereafter. These cells start division and stop the process of division when they are in prophase-I of meiosis-I in the cell cycle. At this stage, these are called primary oocytes.

Additional information:
- The primary oocyte is surrounded by a flattened layer of follicular squamous cells called a primordial follicle. From the period of birth to puberty, a large number of these follicles get degenerated.
- These primordial follicles develop into the secondary follicles and due to the release of estrogen by theca internally the primary oocytes that are in prophase-I complete meiosis-I.
- Now the oocyte formed is called a secondary oocyte which is a large haploid cell, the other cell formed in meiosis-I is a tiny haploid cell called the first polar body.
So, the correct answer is '(b) Constant in number and never be added after the birth'.

Note:
- The secondary oocyte retains the bulk of nutrient-rich cytoplasm of the primary oocyte and it enters into meiosis-II. It divides up to metaphase-II of meiosis-II and stops its division. Now it becomes a mature follicle called Graafian follicle.
- Theca interna that secretes estrogen when a secondary oocyte is formed is a layer formed from the condensation of membrana granulosa.