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.
Film dressings are thin, flexible sheets of clear polyurethane combining an adhesive coating on one side to allow adherence to the skin. The adhesive reacts with wound exudate to prevent adhesion to the wound bed, while allowing the film to stick to the dry, skin surrounding the wound.