Siemenkotelo

Siemenkotelo, commonly referred to as the scrotum in English, is the external pouch of skin and underlying tissue that houses the testicles in male mammals. It sits in the perineal region, between the thighs and behind the penis, and forms part of the male reproductive system. The scrotum protects the testes and helps maintain the temperature required for normal spermatogenesis.

Anatomy and structure: The scrotum consists of skin, subcutaneous tissue, and two layers of smooth muscle—the dartos and the cremaster—that can contract to change the scrotum’s shape and position. Each testis is enclosed by a tunica vaginalis and lies within a separate compartment divided by a scrotal septum. Contents include the testes, epididymides, and the spermatic cords (vessels, nerves, and the vas deferens). Blood supply arises from the testicular arteries, and venous drainage is via the pampiniform plexus, which also helps cool arterial blood before it reaches the testes.

Function: The scrotum helps maintain a temperature roughly 2–4 °C below core body temperature, creating an optimal environment for sperm production and viability. The dartos and cremaster muscles respond to temperature, touch, and arousal to regulate testicular position and protection.

Development: During embryonic development, the scrotum forms from the labioscrotal swellings. In males, it descends with the testes through the inguinal canal into the scrotal sac, with the tunica vaginalis originating from peritoneum.

Clinical relevance: Conditions affecting the scrotum include varicocele, hydrocele, epididymitis, testicular torsion, and inguinal or scrotal hernias. Cryptorchidism, the failure of testicular descent, can also impact the scrotal contents and fertility.