Testis Temperature Relative to Body Temperature in Domestic Animals

Testis temperature of domestic animals is:

Correct Answer: 4–5°C less than body temperature

The testes are located outside the body in the scrotum, which maintains testicular temperature 4–5°C below core body temperature. This cooler environment is essential for normal spermatogenesis — elevated scrotal temperature (cryptorchidism, fever) impairs sperm production.

Mechanisms for Scrotal Cooling

• Pampiniform plexus (counter-current heat exchange): The venous plexus around the testicular artery pre-cools arterial blood before it reaches the testis.
• Scrotal skin: Thin skin with fewer subcutaneous fat layers allows heat dissipation.
• Cremaster muscle: Raises (cryptorchid) or lowers (heat) the testes to regulate temperature.
• Dartos muscle: Contracts (cold) or relaxes (heat) scrotal skin to regulate surface area.

Clinical Importance: Cryptorchidism

In cryptorchidism (undescended testes), the testis remains in the abdominal cavity at body temperature → spermatogenesis fails (infertility) but testosterone secretion (Leydig cells) is preserved → animal is infertile but shows normal male behavior and libido.