Coat (hair), mammals (including humans) unique, formed by the epidermal keratinocytes, cover the surface of a structure in the body. With insulation, protection, feel, and the role of the formation of secondary sexual characteristics.
According to structural features, hair coat can be minute (bristle), lint, and cirrus (sensory hair) 3. Hairs long, thick and tough, according to a certain direction of growth (the hair), has a protective effect. Hair soft and short, in the lower hairs, glabrous to, medulla developed, holding strong. Cirrus is specialized needle wool, and its special structure of the hair follicle, and is rich in nerve endings and can feel the external stimulus, such as some animals, lip, cheek, nose, eyes around the tentacles and human eyelashes.
Hair loss updated regularly, as molt. Molt different animals in different ways: some once a year, such as foxes, rats, etc.; some molt twice a year in spring and autumn, such as mink, squirrel, etc.; some are constantly updated, such as sheep. Some mammals have hair only when the carcass, or the majority of adult hairless body, such as whales, manatees, like the other. Some animals can be special coat into thorns, spines and corners, such as the hedgehog, porcupine spines and rhino horn. |
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