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).
The function of the scrotum is to keep the testicles less warm than the rest of the body. Human testicles work best at 36.8 degrees Celsius (98 degrees Fahrenheit) when normal body temperature is 37 degrees Celsius (98.6 degrees Fahrenheit).