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Why are the testes located in the scrotum outside the abdomen?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

The testes are located in the scrotum outside the abdominal cavity primarily to maintain a temperature several degrees below normal body temperature. This cooler environment is essential for spermatogenesis, the process of producing viable sperm.12

The scrotum acts as a sophisticated temperature-regulating device. It expands and relaxes to promote cooling through air circulation, or contracts in response to cold to conserve heat by pulling the testes closer to the body. Additionally, an intricate network of blood vessels known as the pampiniform plexus within the spermatic cord allows for a countercurrent heat exchange, where warm arterial blood is cooled by the venous blood leaving the testes. Failure to maintain this lower temperature, such as in cases of cryptorchidism or high fevers, can lead to temporary or permanent sterility.13