Wrinkles are a by-product of the aging process. With age, skin cells divide more slowly, and the inner layer, called the dermis, begins to thin. The network of elastin (the protein which causes skin to stretch) and collagen fibers (the major structural proteins in the skin), which support the outer layer, loosen and unravel, causing depressions on the surface. With aging, skin also loses its elasticity and becomes less able to retain moisture, oil-secreting glands are less efficient, and the skin is slower to heal. All of these contribute to the development of wrinkles. Read more about cosmetic procedures for wrinkles.