How do you make a baby? Myself and Georgia Mills have been finding out; here’s the “nuts and bolts” about the cells that make reproduction possible…

• Men make lots of sperm – half a teaspoon contains around 200 million
• Women only release around 500 eggs during their lifetime
• It takes around 2 months from beginning to end to produce one sperm cell
• Women start making eggs 9 weeks after fertilisation and have all of the eggs they will ever produce by the time they are born
• Sperm are tiny at 1/2000th of a centimetre
• Eggs are one of the largest cells in the body at 0.2mm
• Sperm can survive for up to two days inside a woman
• Once a sperm enters an egg the surface immediately transforms into an impenetrable barrier to ensure no other sperm can enter
• The sex of a future baby is determined by the sperm, which can have either an X (female) or a Y chromosome (male)

You can listen to the full interview for the Naked Scientists here.