Until recently we thought that, once broken, the elastic tissue of the skin could never be repaired. Fortunately, the reality turned out the be completely different.
20 % of women suffer from stretch marks. A study carried out in various hospitals of Paris has demonstrated that this proportion was even one out of two during pregnancy. Even if there are no serious pathologic consequences, stretch marks represent an important aesthetic harm by women. They affect 70% of the girls aged from 10 to 16 years, and 90% of the pregnant women, but also 40% of pubescent boys. Stretch marks are an alteration of the elastic fibres of the dermis. They appear on the epidermis like a ridge with a scar-like aspect, pink and later nacreous, the length and the width of which can vary a lot.
The conjunctive tissue (i.e. filling tissues) contains two forms of collagen: normal collagen and a more specific type of collagen, elastin (elastic tissue). They are produced by regenerating cells called fibroblasts. They have the property to continuously produce collagen.
Their disadvantage on the contrary is that they only produce it up to the age of forty. From this age on, the production goes decreasing. Lacking collagen, the elastic network of the skin stretches and eventually breaks. This break is visible at the surface of the epidermis as unsightly marks (a kind of hernia which resembles a burst air chamber), also known as stretch marks.
HOW STRETCH MARKS APPEAR:
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Mechanical theory
: a sudden or progressive distension of the skin, associated with an alteration of its elasticity works in favour of the severing of the elastic fibres.
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Endocrinal theory
: a hypersecretion of certain surrenalian hormones provoking a skin atrophy.
Although age plays a major role in their appearing, other elements also account for it, such as pregnancy, hormonal deregulation, nursing, loss of weight, etc.
The major cause for this elastic break is a lack of water in the cells. As soon as the first signs of dehydration appear, collagen fibres will form a dense network of ramifications which end up by loosing their elasticity and break, leaving visible signs on the epidermis.
Stretch marks always appear around the skin-folds of the body : breasts, stomach, hips, thighs, lower part of the back, arms.
