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.
Collagen for medical use can originate from humans, cows, pigs, or sheep. Skin fillers. Collagen injections can improve the contours of the skin and fill out depressions. Fillers that contain collagen can be used cosmetically to remove lines and wrinkles from the face. It can also improve scars, as long as these do not have a sharp edge.