fertilisation is the joining together - of the sperm and egg, the sperms swim through the cervix, up the uterus - and into the egg tube to find the egg, this is a very long way for the sperm to swim - and most of them will not reach the egg, to overcome these losses millions of sperm - are released into the vagina at once, a number of sperms may reach the egg - but only 1 is able to enter it, this is because the egg makes a skin around itself - to stop other sperms from entering, the egg can live for about a day - and a sperm can live up to 3 days, there are only about 3 days in a month - when it is possible for the egg to be fertilised,

fertilisation process match up

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