Fertilization is the initial stage at which a new human life begins. The method of fertilization is quite complicated. The journey for the egg begins with more than 500 million sperms, released into the cervix of a woman while having sexual intercourse. Fertilization takes place when the strongest swimming sperm travel through the cervix into the uterus, to meet the egg up into one of the fallopian tubes.
The head of a sperm contains an enzyme, which is capable to break the hard outer coating of the egg’s cell membrane. The cell membrane then becomes resistant to all other sperm and does not allow them to get in. Therefore, all the sperms then expire within the next two days.
Fertilization occurs when a sperm enters a mature egg and it releases DNA at the centre of that egg. This enables the sets of DNA to combine and form a human zygote (a single-celled embryo). Then to establish pregnancy it has to travel down into the uterus and implant into the thick coating. There are chances of pregnancy terminated at this point of time, but if everything goes well an early embryo forms and after nine months, a healthy human baby emerges.