Human reproduction and sexual differences

Human start life as a single microscopic cell in the wombs of their mothers. This cell is called a zygote.

The zygote is formed by the union of two cells: the ovum from the mother, and the sperm from the father. This process is called fertilisation.

After the fertilisation, the zygote develops into a small organism called an embryo. Over a period of time, the embryo develops a head, arms and legs.

Many sperm reach the ovum, but only one sperm will actually enter the ovum and fertilise it.

This type of reproduction is called sexual reproduction because it happens through the union of two different individuals: a male who produces the sperm, and a female who produces the ova.

In humans, the males are called men, and the females are called women.