Melasma Overview. Patches of melasma are darker than other areas of skin because they have more pigment. The cells that produce pigment in the skin are called melanocytes. Ultraviolet radiation, or UV rays, from the sun stimulate melanocytes to produce pigment.
The human testicle .The two muscles that regulate the temperature of the testes are the dartos andcremaster muscles:â¢ Dartos Muscle The dartos muscle is a layer of smooth muscle fibers in the subcutaneous tissue of thescrotum (surrounding the scrotum).
Confidence votes 26. The sperm count is dependent on the temperature of the testes. The testes are external to the body because they require a lower temperature to produce viable sperm. The testes work best at temperatures slightly less than core body temperature.Spermatogenesis is less efficient at lower and higher temperatures.This is the reason for retraction of the testes in the cold as well as non-viable sperm in men with (medically) undescended testes.he testes work best at temperatures slightly less than core body temperature. Spermatogenesis is less efficient at lower and higher temperatures. This is the reason for retraction of the testes in the cold as well as non-viable sperm in men with (medically) undescended testes.