Testes

The testes are the male gonads responsible for producing sperm and secreting androgens, primarily testosterone. In humans they are paired organs housed in the scrotum, a skin-covered pouch suspended behind the penis. Each testis is roughly 4–5 cm long and is divided internally into lobules containing seminiferous tubules, where spermatogenesis takes place. Interstitial (Leydig) cells between the tubules produce testosterone, which supports male sexual development and fertility.

Sperm follow a defined path after production: they move from the seminiferous tubules into the rete testis, then through efferent ducts to the epididymis, where they mature and are stored. The epididymis attaches to the posterior aspect of the testis. The scrotal environment, cooler than core body temperature, is important for efficient sperm production; the cremaster and dartos muscles modulate testicular position in response to temperature and arousal.

Vascular and nerve supply: the testes receive arterial blood from the testicular arteries, with venous drainage through the pampiniform plexus into the testicular veins. Innervation arises from the testicular plexus, derived from the abdominal autonomic plexuses.

Development and clinical notes: testes develop near the kidneys in the abdomen and descend into the scrotum via the gubernaculum during fetal life; failure to descend (cryptorchidism) can impact fertility and cancer risk. Common clinical conditions affecting the testes include torsion, infections such as orchitis, hydrocele, varicocele, and testicular cancer, particularly germ-cell tumors. Regular self-examination is often recommended for early detection.