Fertilisation And Implantation

During oogenesis, primary oocyte grows and produces a large secondary oocyte and a small polar body, both haploid. The secondary oocyte next proceeds with meiosis II, but the division gets arrested in metaphase II stage, due to accumulation of metaphase promoting factor (MPF). This is the second resting stage. It is in this stage of oocyte that the ovum is shed during ovulation. It passes into oviduct, where in the ampulla part, cell cycle will resume only after the entry of sperm forming a mature ovum and releasing 2nd polar body. In this way, meiosis Il is completed.