Sperm: the male sex cells

This is the structure of the sperm 

• It consists of a head, body and tail. The head is covered by a cap and contains a nucleus of genetic material.
• It is attached to a region containing mitochondria, which supply the energy for the sperm's activity. 
• The sperm make up 5% of what a man ejaculates during the sex act. This represents 100 to 400 million sperm each time, carried in a nutritious fluid (semen). 

Ova: the female sex cells

This is an ovum

• Each ovum is a large cell, with an external cell membrane, and is full of liquid rich in protein. 
• It has a nucleus containing the female genetic material
• The ova are stored in ovarian follicles in the ovaries, and a few being to mature each month after a girl reaches puberty at about 12-15 years of age when menstruation occurs.