Write a short note on oogenesis.

Explanation

Oogenesis is the process of production of eggs (ova) that starts in ovaries of female foetus. It begins before the birth but completes only after fertilisation. It is comprised of the following three main stages
(i) Multiplication phase Germinal epithelium is divided to form oogonia.
(ii) Growth phase Oogonia cells increase in size and form primary oocytes.
(iii) Maturation phase Primary oocyte gets divided into two unequal cells. Larger cell is called secondary oocyte and the smaller cell is known as first polar body. From secondary oocyte ovum is formed.