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 sac between a man's legs is called the scrotum. It is what protects and contains the testes. The scrotum also regulates the temperature of the testes.When they are hot, â¦ the skin becomes very soft, and there may even be sweating.When the testes are cold, the skin of the scrotum becomes stiff, shrunken, and leathery.t is what protects and contains the testes. The scrotum also regulates the temperature of the testes. When they are hot, â¦ the skin becomes very soft, and there may even be sweating. When the testes are cold, the skin of the scrotum becomes stiff, shrunken, and leathery.