Reproduction

Puberty is the period during adolescence when the body changes from a child into an adult capable of reproducing. The changes are triggered by sex hormones released by the reproductive organs:

• Testosterone from the testes in males
• Oestrogen (and progesterone) from the ovaries in females

The changes are called secondary sexual characteristics to distinguish them from the primary sexual characteristics (the reproductive organs themselves, which were present from birth).

Male secondary sexual characteristics

Triggered by rising testosterone:

• Growth of the penis and testes to adult size
• Sperm production begins
• Growth of pubic, underarm and facial hair
• The voice deepens as the larynx (voice box) enlarges
• Increased muscle mass and broader shoulders
• A growth spurt that adds height
• Skin becomes oilier (often causing acne)

Female secondary sexual characteristics

Triggered by rising oestrogen:

• Breast development
• Hips widen to make room for childbirth
• Growth of pubic and underarm hair
• The menstrual cycle begins (the first period is called menarche)
• A growth spurt that adds height
• Body shape becomes more curved as fat is laid down on the hips, thighs and breasts
• Skin becomes oilier (often causing acne)

Common to both sexes

Some changes happen in everyone during puberty:

• Body hair grows
• Sweat glands become more active (with body odour)
• Mood swings and emotional changes due to changing hormone levels
• Growing interest in sex and relationships