testiculus

In anatomy, testiculus (plural: testiculi) is a Latin-derived term referring to a testis, the male gonad found in vertebrates. In mammals the paired testiculi are responsible for producing spermatozoa and the primary male sex hormone testosterone. They are typically suspended in the scrotum outside the abdominal cavity in many species, a position that helps maintain a lower temperature optimum for spermatogenesis.

Microscopically each testiculus contains coiled seminiferous tubules where germ cells develop, supported by Sertoli cells. Interstitial Leydig cells synthesize testosterone under luteinizing hormone stimulation. The organ is covered by a dense fibrous layer, the tunica albuginea, and connects to the male reproductive tract via the epididymis and vas deferens.

Embryologically, testiculi develop from the genital ridge and usually descend into the scrotum guided by the gubernaculum; failure to descend is termed cryptorchidism. Vascular supply arises from the testicular arteries (branches of the abdominal aorta) and venous drainage occurs through the pampiniform plexus into the testicular veins. Lymphatic drainage is to the para-aortic nodes.

Clinical issues involving the testiculus include torsion (acute vascular compromise), infections such as orchitis, varicocele, and testicular neoplasms, which are a leading cancer type in younger adult males. Assessment of size, consistency, and position is important in medical evaluation and fertility assessment. The word testiculus is a diminutive of the Latin testis.