The dermis contains tough connective tissue as well as different types of cells and glands. It is composed of a network of tough connective tissue fibres, blood, lymph capillaries and sense organs. Towards the bottom of the dermis there are sweat glands from which narrow sweat ducts run to the surface of the skin. Projecting out of the skin are hairs. Each hair projects from a hair follicle and its root is situated deep in the dermis. Opening into the hair follicles are glands which produce oil, they are known as sebaceous glands, the oil they produce is known as sebum, this keeps the hair supple and helps make the skin waterproof.

The average thickness of the dermis is 3mm and it is made up of 2 regions:

  1. The Papillary Layer – This region interlocks with the epidermis in series of ridges sometimes referred to as the dermal papillae. This layer is continuous around each hair follicle forming a connective tissue sheath. The papillary layer contains a network of blood capillaries to supply the needs of the living cells in this region. The papillary region is made up of collagen fibres, with non-elastic protein fibres and some yellow elastic fibres.
  2. The Reticular Layer – This lies beneath the papillary layer and is made up of a dense network of collagen fibres that are arranged in layers and between which there are many elastic fibres.

This arrangement allows the skin to stretch but return to its original form when the stretching forces are removed. A jelly-like ground material of mucopolysaccharides absorbs considerable amounts of water making the skin turgid or taut.

Dermal Cells

There are 3 main types of cells in the dermis:

  • Mast Cells – When the skin is damaged, they secrete histamine which results in dilation of the blood vessels, increasing blood flow and aiding healing.
  • Leucocytes – These cells are white blood corpuscles that can deal with bacteria or foreign material present in the skin which could lead to infection.
  • Fibroblasts – These are involved in collagen fibre production as well as producing the ground material of the dermis.
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