Gonad

The gonad is the organ that makes gametes. Gametes are haploid germ cells. For example, sperm and egg cells are gametes. The gonads are a combined gland providing both exocrine and endocrine functions.

In males, the male gonads, known as the testes or testicles, secrete the class of hormones called androgens, and produce spermatazoa. The predominant androgen in males is testosterone. In females, the female gonads, known as the ovaries, secrete the hormones estrogen and progesterone, as well as ovum. The dominant estrogen is known as estradiol, which is derived from testosterone.

The gonads are controlled hormonally by luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secreted by the anterior pituitary gland. The anterior pituitary gland's excretion of LH and FSH are, in turn, controlled by the hypothalamus' gonadotropin-releasing hormone.

Gonads start developing as a common anlage, and only later are differentiated to male or female sex organs. The SRY gene, located on the Y chromosome and encoding the testis determining factor, decides the direction of this differentiation.

Although medically the term can refer to either male gonads (testicles) or female gonads (ovaries), the vernacular, or slang use of "gonads" (or "nads") usually only refers to the testicles.