What are Stretch Marks?

Everyone wants to know… what are stretch marks really? Well… Stretch marksor striae (singular stria), as they are called in dermatology, are a form of scarring on the skin with an off-color hue. They are generally caused by the tearing of the dermis, and over time can diminish but will never disappear completely. They generally ccur when the middle layer of your skin, the dermis, is stretched past its elasticity and begins to tear. Tiny blood vessels break, and blood pools under the skin, which yields a striated purplish to reddish tint when observing new stretch marks.

Stretch marks are often the result of the rapid stretching of the skin associated with rapid growth. Stretch marks may also be influenced by hormonal changes associated with puberty, pregnancy, muscle building, hormone replacement therapy for transsexuals, etc. Medical terminology for these kinds of markings includes striae atrophicae, vergetures, stria distensae, striae cutis distensae, striae gravidarum (in cases where it is caused by pregnancy), lineae atrophicae, linea albicante, or simply striae.

What Stretch Marks are (simplified)

In short, a better way to understand stretch marks is to understand what skin is made of and how it works. Normal skin is 80% collagen and 4% elastin fiber mesh network (dry weight). This Elastin is the protein in the skin which gives it its flexibility and allows it to stretch. The elastin forms a fishnet-like network in the skin which allows our skin to stretch and recoil back to its original position.
Stretch Marks are simply Damaged Elastin

These elastin fibers are damaged in stretch marks, causing the ‘scar’ of a stretch mark. What’s so remarkable about stretch marks is how prominent they look, but under a microscope you see almost no difference from normal, healthy skin. If you touch a stretch mark, it feels empty, almost like there is no skin there. Visually and textually the skin is so very different, yet so little has actually changed in the skin.

Why don’t these stretch marks heal over time?

Stretch marks are a huge problem. The problem with stretch marks is the elastic fibers in skin with stretch marks are damaged, and elastic fibers are the single hardest thing to repair in the skin. When you have a wound that’s healing, our body replaces the collagen proteins and all the skin structures that are injured, but the elastic fiber is very difficult to repair. The trouble with stretch marks is that there’s this defect in those fibers. So since our bodies cannot effectively repair these fibers, the stretch marks do not heal as one would wish for them to.

What are Stretch Marks