How Stretch Marks Are Formed
Stretch marks are slightly depressed linear marks with varying length and breath found on certain parts of the body in conditions like pregnancy, obesity, puberty etc due to the excessive stretching of skin for a long period.
It has already been mentioned that the quality and strength of the skin depends on certain factors like general health, nutrition, hydration, hereditary factors, environmental conditions, hygiene, healthcare, skin care etc. A healthy skin can be stretched to some extent especially when the enlargement of skin is gradual. But when the body surface area increases in a short span of time there will be excessive stretching of the skin resulting in breaking of collagen and elastin present in the dermis.
When these protein fibers break, some kind of itching may be felt, but no pain. Along with breaking of fibers there will be dilatation of small blood vessels present in the skin, which results in red or purple stretch marks called stria rubra. Later, with the advancement of time there will be remodeling of skin with loss of melanin in the affected area and this causes them to become pale and silvery white in color. Now it is called stria alba. However in such cases they may appear as faint pale markings.
The length of stretch marks may vary and their average width is 1 to 10 mm. They are seen parallel to each other and make an angle of 90° with the direction of stretching of skin. These markings are actually formed in the deep tissues of the skin and gradually they appear on the skin surface. The usual sites are abdomen, buttocks, breasts, thighs, shoulders etc.