At puberty the sex hormones cause the secondary sexual characteristics. Testosterone is the main male sex hormone. It is made in the testes and causes sperm production, a deeper voice, facial hair and more muscle. Oestrogen is the main female sex hormone. It is made in the ovaries and causes breast development and wider hips. It also has a job in the menstrual cycle.
The menstrual cycle is the monthly series of changes in a woman's body. It lasts about 28 days. During menstruation the lining of the uterus is lost. The lining then repairs and thickens, an egg is released from an ovary at ovulation around day 14, and the lining stays thick in case the egg is fertilised.
Four hormones control this. FSH is made in the pituitary gland and causes an egg to mature in the ovary. LH is also made in the pituitary gland and triggers ovulation. Oestrogen, made in the ovaries, repairs and thickens the lining of the uterus. Progesterone, also made in the ovaries, keeps the lining thick.
