B) Dermis

The dermis is mesenchymal tissue that supports the epidermis. Many of the skin appendages extend into (or through) the dermis.

Structure

The dermis is arranged in two distinct layers:

  • The papillary dermis consists of loose connective tissue which interdigitates with the epidermis. These papillae are variable in size; they tend to be more pronounced in thick skin. Capillaries from a plexus of vessels between the papillary and rete dermis ascend into the papillae to supply the epidermis.
  • The rete dermis is formed by denser, elastic connective tissue. It contains elastic collagen arranged haphazardly throughout. There are numerous larger vessels (arterioles and venules), nerves and mast cells. The roots of the skin appendages often lie in the rete dermis.

The epidermis lies superficial and the hypodermis lies deep to the dermis.

Malignancy

Most tumours do not arise in the dermis but invade into it from the epidermis. Sarcomas and sweat gland tumours may arise primarily in the dermis.


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