The epidermis (outer layer), the dermis (middle layer) and the subcutaneous stratum (innermost layer) make up the three layers of skin.
Stretch marks occur in the resilient middle layer that helps the skin retain its shape or the dermis.
The skin becomes less elastic and the small connective fibers within it break when the dermis is constantly stretched over time. The result is what we know as stretch marks.
For most girls and boys, stretch marks are a normal part of puberty. When a person grows or gains weight really quickly, like during puberty, that person may get fine lines on the body called stretch marks.Read More