Which accessory structure is involved in regulating body temperature?

Sweat glands play a crucial role in regulating body temperature through the process of perspiration. When the body heats up, these glands produce sweat, which is primarily composed of water and salts. As the sweat evaporates from the surface of the skin, it cools the body down, helping to maintain a stable internal temperature. This thermoregulation is essential, especially during exercise or in hot environmental conditions, as it prevents overheating and maintains homeostasis.

Other accessory structures, such as sebaceous glands, hair follicles, and nails, do not directly participate in temperature regulation. Sebaceous glands produce oil to lubricate the skin and hair, while hair follicles are involved in the growth of hair, which can provide some insulation but does not directly regulate temperature. Nails protect the tips of fingers and toes but have no significant role in thermoregulation. Thus, the involvement of sweat glands in body temperature regulation makes it the correct answer.