Fertilisation and implantation

The cortical reaction

This involves vesicles called cortical granules located within the oocyte. they make the zona pellucida impermeable to additional sperm by fusing with the cell membrane to form the fertilization membrane. This prevents polyspermy which is the fertilisation of the egg by several sperm. 

Post-fertilisation

The second polar body degenerates. The embryo now produces a hormone stimulus called human chorionic gonadotrophin to maintain progesterone production from corpus luteum and prevents the…