Under gonads the exocrine units testis and ovaries are summarized. The hormonal action of the hypothalamus and pituitary gland (FSH and LH), causes a change in the ovary, whereby the oocytes maturing within it increasingly produce estrogen until ovulation. If LH secretion occurs, ovulation is ultimately triggered and the female sexual organs are prepared to receive sperm. Once ovulation is complete, a corpus luteum develops, which produces progesterone and another form of estrogen while inhibiting the hypothalamus and pituitary gland. The male testis, like the ovary, is controlled by hormones (FSH and LH) from the pituitary gland. It contains the Leydig intermediate cells, which produce the male sex hormone testosterone, and the Sertoli cells, which produce inhibin and an androgen-binding protein (ABP) and are important for spermatogenesis.