What does scar tissue typically lack?

Scar tissue typically lacks hair and sweat glands. When the skin heals from an injury, the body repairs the damaged area with fibrous tissue that differs from normal skin. This new tissue is primarily composed of collagen and does not develop the same structures as the original skin, such as hair follicles and sweat glands. As a result, scar tissue can appear different in texture and color compared to surrounding skin, often being smoother and less functional.

Normal skin contains these functional components—hair follicles and sweat glands—that contribute to skin's overall texture and regulation of body temperature. The absence of these elements in scar tissue can lead to reduced functionality in that area of the skin, making it distinct from the original skin.

In terms of the other options, scar tissue does contain collagen fibers, though they are arranged differently compared to normal skin, and while it may lack some color pigmentation due to differences in vascular supply, the primary lack of functional structures like hair and sweat glands is a defining characteristic of scar tissue. Additionally, the question of elasticity is also related, as scar tissue may be less elastic than surrounding tissue due to the nature of the collagen formation. However, the most definitive characteristic that distinguishes scar tissue in this context is the absence of hair and sweat glands.