This is truly one of nature’s miracles. Of the millions of sperm released during an ejaculation, only a few hundred will survive to make the arduous trip to the egg. Of the few hundred sperm, which reach the egg, only one will successfully fertilize it. In the process of fertilization, the female’s chromosomes in the egg and the male’s chromosomes in the sperms fuse together to create a new life- one which is totally different from all others, because of its unique genetic composition.
During the time that the sperm spend in the female reproductive tract, while swimming towards the egg, they acquire the capacity to fertilize it- a process called capacitation. When the sperm reach the corona cells they become hyper activated start beating their tails in a frency. This hyper activation is useful because it provided the mechanical energy that the sperm head needs to burrow its way through the outer shell of the egg called the zona. The sperm disperse the cumulus oophorus and when they reach the egg, they first bind themselves to the zona. A chemical is released here buy the sperm in a process called the acrosomal reaction in which the acrosome is removed. The acrosomal enzymes dissolve the zona pellucid by making a tiny hole in it, so that one sperm can swim through and reach the surface of the egg. At this time, the egg transforms the zona to impenetrable barriers, thus preventing other sperm from entering.
The genetic material of the sperm the male pro nucleus and the genetic material of the egg the female pro nucleus then fuse to form an embryo, which then divides into 2 cells. These cells, in turn, thereafter continue to divide rapidly, producing a ball of cells now called the blastocyst. The embryo next travels through the fallopian tube (which nurtured it; and at the appropriate time, propels it) into the uterus. At this takes about 3 to 5 days. The embryo must then break through its zona this is called embryo hatching, and them attach itself to the lining of the uterus in a process called implantation, and in 9 months, if all goes well, a baby will born.