Answer:
There is thinning of the dermis with eventual collagen realignment and deposition. The epidermis shows thickening. Fat may be compressed and atrophy. Thin muscles, such as the frontalis, may also thin and atrophy. Skin appendages are largely unaffected. The cited study showed a three-fold elevation in epidermal mitotic activity in guinea pig skin within 24 hours of expansion. The authors speculate that the epidermis is stimulated by a reversal in the “density inhibition” mechanism. They conclude that tissue expansion is a “dividend derived from the judicious use of a biological asset: the ability of the epidermal cell to replicate.”