The skin is the largest organ of the body, with a surface area of 18 square feet. Its two main layers are the epidermis (outer layer) and dermis (inner layer). And what you ask is DERMIS (thicker inner layer) .The dermis varies in thickness depending on the location of the skin. It is .3 mm on the eyelid and 3.0 mm on the back. The dermis is composed of three types of tissue that are present throughout - not in layers. The types of tissue are:collagenelastic tissuereticular fibersLayers of the DermisThe two layers of the dermis are the papillary and reticular layers.The upper, papillary layer, contains a thin arrangement of collagen fibers.The lower, reticular layer, is thicker and made of thick collagen fibers that are arranged parallel to the surface of the skin.