Additionally, the cellular and extracellular matrix alterations that mediate the clinical phenotype of stretch marks remain poorly understood. In the latter, striae are characterized by their inordinate breadth, depth, and intense color. These lesions may resemble striae distensae, but they are palpable rather than depressed and yellow rather than purplish or white. In the later stages, the epidermis becomes thin and flattened with loss of the rete ridges. The dermis has thin, densely packed collagen bundles arranged in a parallel array horizontal to the epidermis at the level of the papillary dermis.
Elastic stains show breakage and retraction of the elastic fibers in the reticular dermis.
The broken elastic fibers curl at the sides of the striae to form a distinctive pattern. Scanning electron microscopy shows extensive tangles of fine curled elastic fibers with a very random arrangement. This is in contrast to normal skin, which has thick elastic fibers with a regular distribution. When viewed by transmission electron microscopy, the ultrastructure of elastic and collagen fibers in striae is similar to that of normal skin. The peels can be repeated at monthly intervals.