The gonads are the main source of sex hormones in males, located in
the testes and in females the ovaries. The secretion of sex hormones by
the gonads are controlled by the pituitary gland hormones such as FSH
and LH.

The testes secrete hormones called androgens, with the principle one
being testosterone. Production of testosterone begins during fetal
development, and nearly ceases during childhood. All of these hormones
play an important role in puberty and sexual development as well as
producing sperm by the testes.

The ovaries secrete two female hormones; oestrogen and progesterone,
with the former being involved in the development of features such as
breast growth and the accumulation of body fat around the hips and
thighs. Progesterone causes the uterine lining to thicken in preparation
for pregnancy.