testicles

The testicles, or testes, are a pair of oval male reproductive glands located in the scrotum. They serve two primary roles: the production of sperm (spermatogenesis) and the synthesis of the male hormone testosterone. In adults, each testis is roughly 4 to 5 cm long and about 2 to 3 cm in width. They are enclosed by a tough fibrous capsule called the tunica albuginea and are separated into lobules by connective tissue septa.

Anatomy and location: Each testis contains many seminiferous tubules where sperm cells develop. Interstitial (Leydig) cells between the tubules produce testosterone. The tunica vaginalis surrounds the testis, and the mediastinum testis contains ducts that collect sperm. The epididymis, attached to the posterior aspect of the testis, stores and matures sperm before they enter the vas deferens.

Development and function: In fetal development, the testes originate near the kidneys and descend into the scrotum through the inguinal canal, guided by the gubernaculum. The cooler temperature of the scrotum is important for normal spermatogenesis. After puberty, testosterone supports sexual development, muscle mass, and secondary sexual characteristics, while sperm production continues in the seminiferous tubules.

Blood supply, innervation, and drainage: The testicular arteries arise from the abdominal aorta. Venous drainage occurs via the pampiniform plexus, which helps cool arterial blood. Lymph drains to lumbar (para-aortic) nodes. Innervation includes autonomic nerves that regulate blood flow and testicular function.

Clinical notes: Common conditions affecting the testes include cryptorchidism (undescended testis), torsion, epididymitis, hydrocele, and varicocele. Testicular cancer risk is higher in undescended testes, emphasizing the importance of self-examination and medical evaluation for any lump, pain, or swelling.