"Gonad" redirects here. For gonads of non-human organisms, see Sex organ
The gonad is the organ that makes gametes. The gonads in males are the testes, and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes.
The gonads are controlled hormonally by luteinizing hormone (Le) and follicle-stimulating hormone (FSH) secreted by the anterior pituitary gland. This secretion in turn is controlled by the hypothalamus' gonadotropin-releasing hormone.
Gonads start developing as a common anlage (an organ in the earliest stage of development), in the form of gonadal ridges, and only later are differentiated to male or female sex organs. The presence of the SRY gene, located on the Y chromosome and encoding the testis determining factor, determines male sexual differentiation. In the absence of the SRY gene from the Y chromosome, the female sex (ovaries instead of testis) will develop. The development of gonads is a part of the development of the urinary and reproductive organs.