It's only a mature sperm that can fertilize an egg and eventually produce a baby.

So, unlike in humans, every chimp male's sperm has to fight really hard to fertilize a single egg.

For each chromosome contributed by the sperm there is a corresponding chromosome contributed by the egg, there are two chromosomes of each kind, which together constitute a pair.

Man comes not from an egg but from an animalcule that is found in male sperm.

The male function is to produce sperm. We now have sperm banks.

When we use fresh sperm, the surgical procedures for the sperm retrieval and egg retrieval need to be done the same day, and this may not be convenient for the couple. However, if we use frozen sperm, the man can have his procedure first, and if we find sperm, we can bank it. Then, at the couple's convenience we do egg retrieval and the fertilization procedure that puts the egg and sperm together. The model helps us know in advance when frozen sperm would allow for good results for that couple.