Question

Given below are the steps involved in oogenesis. Arrange them in proper sequence and select the correct option.
$1.$ Formation of primary follicle due to development of granulosa cells.
$2.$ Division of oogonia and formation of the primary oocyte.
$3.$ Formation of follicles having antrum.
$4.$ Formation of secondary follicles.
$5.$ An unequal division leading to the formation of secondary oocyte i.e. ovum and the first polar body.

• A. $1, \, 3, \, 4, \, 2, \, 5$
• B. $2, \, 1, \, 4, \, 3, \, 5$
• C. $3, \, 1, \, 2, \, 4, \, 5$
• D. $1, \, 5, \, 3, \, 2, \, 4$

Answer 1

Answer: (B)

The sequence of oogenesis (formation of ovum) is as follows:
Millions of oogonia are added in a female fetal ovary after birth. These oogonia undergo division and lead to the formation of primary oocytes. A layer of granulosa cells surrounds these oocytes, which leads to the formation of primary follicles. More and more layer of granulosa cells and a new theca surround these primary follicles which leads to the formation of secondary follicles A fluid filled cavity called antrum develops which leads to the formation of tertiary follicle. An unequal division of the tertiary follicle leads to the formation of a haploid secondary oocyte i.e. ovum and a tiny first polar body.