There are several layers of skin. The outer skin which everyone can see is called the epidermis. The second layer, which is not visible, is called the dermis. It is made up of loose tissue, contains many glands and nerves. The dermis has variable thickness ranging from 0.5 to 3 mm. it is thinnest in the eye and thickest in the soles of the feet and the back.
The dermis is structurally sub divided into two segments: a superficial area adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular region
Both these segments contain vital structures for skin survival. All types of nerves are present in the dermis. These nerves can sense pain, position, touch, temperature and pressure. The glands serve to secrete protective oils and hair.
The dermis serves to protect the underlying structures.
The dermis is also vulnerable to injury and disease. Most skin cancers begin in the dermis and so do most infections. The dermis is a loose structure and for this reason is susceptible to stretch.
Stretch marks during pregnancy are due to the loosening of dermal tissue.