Only dermis is vascularized. Nutrients reach epidermis by diffusing through the tissue from the blood vessels. Underneath dermis is hypodermis (superficial fascia), also called subcutaneous tissue which is composed of loose connective tissue (mostly areolar and adipose).
A collagen dressing is a type of wound dressing that is made with a form of collagen to aid in the body's healing processes. Collagen is a category of structural proteins that are naturally present in almost every part of the human body and are especially common in connective tissue.
Drainage requirements: may be supplied with any kind of drainage. These dressings come in pads, gels or particles and promote the deposit of newly formed collagen in the wound bed. They can be used on any type of wound with any type of drainage. Some specific brands require the wound to be free of necrotic tissue.