Answer:
Relaxation of the dartos muscle.
Explanation:
Testes are present in scrotum outside the pelvic cavity to maintain the temperature about 2-3 degrees Celsius below the body temperature as required for sperm production. Dartos muscle is the layer of smooth muscle located in the superficial fascia. The contraction of dartos muscle serves to make the skin of the scrotum wrinkled and tight.
During hot weather, the dartos muscle relaxes and makes the surface of scrotum less wrinkled to increase the loss of the heat from its surface. The increased heat loss from the surface of scrotum due to relaxed dartos muscles keeps the testes protected from heat.
