The skin is the outer covering of the body and is vital in protecting the body against pathogens and excessive water loss. Its other important functions include insulation, temperature regulation and sensation. The skin of humans and other mammals is composed of two major layers: (1) epidermis (the more superficial layer) and (2) dermis (the deeper layer). The dermis can be further divided into two major layers: the papillary dermis and the reticular dermis. Compared with the reticular dermis, the papillary dermis is thinner and more superficial. The papillary dermis is the layer of the dermis closer to the epidermis Its basic components include connective tissues, lymphatic plexuses, and blood vessels. In particular, it is made up of areolar connective tissues. Its name is derived from the dermal papillae it forms. These papillae are small, nipple-like extensions of the dermis into the epidermis. The papilla may contain terminal networks of blood capillaries or tactile Meissner's corpuscles. The papillae increase the surface area of the dermal/epidermal junction.