To begin, we must look into the skin itself before moving directly to stretch marks.

The skin of composed of a connective network formed by elastin and collagen. It is fundamental to understand that elastin is a protein that permits the skin to be elongated to a certain point and then to go right back how is was. Once stretch marks have appeared it actually means that the elastin has been damaged.

A scar is what replaces normal skin after an "injury"(any type of damage to the skin). To quickly connect collagen and elastin fibers, the body leaves us with stretch marks. Stretch marks are a consequence of a stretching that wounds the skin because that skin cannot endure the stretching of the skin. A stretch mark is a result of a weakening of the "skin network", which includes the cells and the connective fibre tissues in between the first and second later of skin. A scar is a mark that may appear to be on your skin's surface but is really underneath it. This type of scar is also referred to in some cases as a linear atrophic lesion.

Now we must understand what's happening at the area of the elastin fibres and collagen network. Elastin fibers (or yellow fibers) are bundles of proteins (elastin) found in connective tissue. Elastin fibers can be pulled to grow up to 1.5 times their size and then once untensed can move back to the original size. But when the "stretching of the skin", snaps back, it may leave what we call a stretch mark.

How Stretch Marks are Formed

Basically what stretch marks are is damaged tissue, this is what makes the fibrocytes react and put into movement a process of mitosis of the fibrocytes.

This process of mitosis may leave you with a group of stretch marks instead of just one. Stretch marks may appear for other reasons than just "stretched skin". In fact there exist many reasons for the appearance of "stretch marks".

* The first factor is strictly mechanical. It is related to the skins fragility experienced mostly through pregnancy, fast weight gain or loss, growth.

* The second factor is related to the malfunction of the pituitary-hypothalamic complex radicating from the endocrine system. This may lead to a disregulation of cortisol, which is what causes the collagen network to weaken. Clinically induced factors are related to the use of corticoids.

* Sugar metabolism disorders or glycation are a metabolic factor. These disorders interfere with the biosynthesis process of the fibroblasts, in the end they create cross links with collagen and the collagen network, thus; reducing the skin's elasticity.

We can see now that stretch marks are not merely growth and weight related, but also very susceptible to clinical and hormonal reasons. Stretch marks can appear because of many things, but they are indisputably the same; whitish/pinkish, elongated line that presents itself as tough and annoying as any other scar and just as difficult to remove no matter what stretch marks removal.