This sqadia.com short video clip is brief explanation of Zygote by Ms. Sidra Afzal.
The capacitated sperm can freely penetrate through the corona radiata to reach the zone pellucida by the movements of its tail. When the head of sperm meets zona pellucida, the acrosome releases digestive enzymes, which cause lysis of zona pellucida and plasma membrane around the head of the sperm.
The head and tail of sperm enter the cytoplasm of the oocyte. The sperms move forward to come in close contact with the female pronucleus. Its nucleus becomes swollen and forms the male pronucleus. The male and female pronuclei lose their cell membrane and chromosomes of two nuclei mix together to form diploid. The ootid becomes a zygote.