It is a process of formation of a mature ovum from the oogonia in female ovary. During oogenesis, the diploid oogonium sixe increased and formed into a diploid primary oocyte. This diploid primary oocyte undergoes first meiotic division (meiosis I) and forms two unequal haploid cells. The small cell is called as first polar body, whereas large cell is known as secondary oocyte. The secondary oocyte further divided into two unequal cells, i.e. second polar body and an ovum (egg cell). Hence, in oogenesis process, a diploid oogonium produces a single haploid ovum, and more than one polar bodies.