Male and Female
The testes are inside a sac called the scrotum.
It hangs outside the body, keeping the sperm cool.
Sperms only develop properly in cool conditions.
Sperms are produced all the time.
They are stored in small tubes outside the testes.
Eventually they pass along a much bigger tube called the sperm tube.
Glands add a fluid which keeps the sperms alive.
The sperms and the fluid are called semen.
The penis must be erect for the semen to pass out.
This happens when blood is pumped into special spongy tissue in the penis.
During an ejaculation semen is pumped out of the penis – due to a contraction of the muscles around the sperm tubes.
Each ejaculation makes about a teaspoon of semen but this can contain: 500 million sperms.
The ovaries are the female sex organs.
They produce the eggs.
They also make the female hormones oestrogen and progesteron (between 10 and 15 years).
An egg is released about every 28 days.
The egg passes out of the ovary and moves into the egg tube.
This is called ovulation and is when an egg may become fertilized.
The egg slowly moves down towards the uterus (womb).
If sperms are present in the egg tube the egg will be fertilised.
If the egg is not fertilised it will dies after about a day.