Male and female reproductive systems allow human reproduction. Fertilisation occurs when a sperm and egg join to form an embryo. An embryo develops into an unborn baby in the uterus during pregnancy.

and altered it to allow two parent cells to combine to create offspring (sexual reproduction). It met this challenge by devising (again, speaking from a human perspective) a system by which parent ...

However, in the animal world there are many examples of “virgin” or asexual reproduction, in which only one individual, necessarily female ... to produce human beings from asexual reproduction ...