How does fertilization takes places?

Answer 1

By the fusion of egg with sperm.

Answer 2

The actual process is very interesting and very complicated. Sperms are like guided missiles and they charge towards the ovum, which secretes an odorant (smell producing) molecule; being guided by the sperm's own 'smell tracking heads'. This is pretty similar to the patriot missile, which latches onto heat.

Now, of so many sperms, only one can penetrate this fortress called ovum. Fortress because, once ONE sperm makes its way into it, the ovum enables its (ovum's) own firewall, so that no second sperm can get in. Once they go near the ovum and come in contact, they secrete an enzyme, hyaluronidase, which melts the ovum's tough covering called zona pellucida, only then it can enter. By the way, the sperm doesn't enter as a whole, rather it leaves its skin (plasma membrane) behind. This meeting of sperm and ovum is called fertilization. This process occurs, in most cases, in the ampullary portion of the Fallopian tube. Once the Sperm is inside, its chromosomes (23 in number), mix with the 23 chromosomes of the ovum, making the total tally to 46, a diploid number. Thus the entity that forms, the zygote, starts multiplying into a full blown fetus, in the course of time. The sex of the fetus is determined by the X or Y chromosome of the sperm, which comes from the father.

However, if we think too much about it, it will take away all the pleasures we derive from the process of procreation. I would rather be oblivious about it myself! Iloveyou