The Dermis

The dermis, also referred to as the corium or ‘leathery skin’, lies just beneath the basal membrane of epidermis and extends to the subcutis (hypodermis). While the border between the epidermis and dermis is well-defined, the border between the dermis and subcutis is more fluid.

The dermis is comprised of an upper layer, called the stratum papillare, which forms the defined, wave-like border with the epidermis, and a lower layer, the stratum reticulare, that runs continually in the deep subcutis layer.

1 Stratum papillare
2 Basal membrand
3 Basal Cells
4 Epidermis

The wavy border between the epidermis and dermis increases the contact area between the two layers, ensuring optimal nourishment of the basal cells by blood cells running through the stratum papillare.

The dermal layer is largely made up of connective tissues that are either arc shape or wave shaped elastic fibres or slightly supple collagen fibres. These connective tissues are responsible for the high elasticity and strength of the skin. Collagen fibers combine with long chains of sugar molecules call glycosaminoglycanes (or mucopolysaccharides) to form complexes with a high capacity to bind with water. This provides the high intrinsic tension (tautness) of the young skin. As skin ages, the ability of the dermis to form these complexes diminishes along with its water-binding capacity. As a result, the skin is less toned and more prone to wrinkles.

In addition to connective tissue, the dermal layer contains various other types of cells, such as fibroblasts and mast cells, as well as numerous blood and lymph vessels, nerve endings, hot and cold nerve receptors, as well as tactile sense organs. Hair roots (the bulbous end of the hair shaft where hair is developed), sebaceous glands (which are almost always attached to hair shafts) and sweat glands are also located in the dermis. Hair produced in the root reaches the skin’s surface through a lined opening called a follicle. Oils produced in sebaceous glands also travel to the skin’s surface through hair follicles. Sweat produced in the sweat glands reach the skin’s surface through openings called pores that extend from the root or gland upward through the epidermis to the skin’s surface. The moisture and oils secreted from the sweat and oil glands make up a hydrolipid film that covers the surface of the skin.

1. Hair shaft

2. Sebaceous gland

3. Bulbis

4. Hair papilla

5. Sweat gland