any of the hormones that stimulate various reproductive functions. Primary sources of sex hormones are the male and female gonads (i.e., testis and ovary), which are stimulated to produce sex hormones by the
follicle-stimulating hormone and
luteinizing hormone secreted by the pituitary gland. The principal male sex hormones (
androgens) include testosterone; female sex hormones include the
estrogens,
progesterone, and
prolactin.