The egg cell ( ovum ) starts its development when the female foetus is 8 to 20 weeks old.
These primary oocytes begin their first meiotic division but which arrests until later. The ova remain dormant in the female till the time of ovulation i.e. when the ovum is released from the ovary.
At this time the ovum undergoes further meiotic division to form a secondary ovum and a polar body.
The secondary oocyte grows in the ovary until it reaches maturation. Once mature it is carried to the fallopian tubes, where it is suitable for fertilization.