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 body has thousands of eccrine glands, which effectively regulate the body's temperature. As the body's temperature rises, the nervous system goes to work to stimulate the eccrine glands to release sweat. Sweat is made up of water, sodium and other substances that help cool the body down.