Changes in males

These changes begin to occur between the ages of 13 and 16 years. The activity of the hormone testosterone is responsible for them.

• Hair grows on the face, the chest, the armpits, the groin and around the reproductive organs.
• The shoulders broaden.
• The larynx enlarges and the voice deepens.
• The growth of bones and muscles becomes rapid and the body grows larger.
• The production of sperm begins in the testes.
• The reproductive organs grow and become larger.