Structure of skin. ~largest organ in the body comprises 16% of body weight surface area 1.8 m square. ~structure and thickness vary with site the thickness varies between 0.6 mm and 3 mm. ~skin is composed of three layers epidermis dermis and subcutaneous fat. the epidermis mainly composed of ~Keratinocytes is arranged in four layers: stratum corneum, stratum granulosum, stratum spinosum and stratum basale. ~stratum granulosum, stratum spinosum and stratum Basale together forms the living layer and constitute the site of synthesis of Keratin. ~stratum corneum is the dead layer and constitutes the main barrier. ~the other main cells in epidermis are melanocytes, langerhans cells and merkel cells. ~dermis is made up of papillary dermis just beneath the epidermis and deeper reticular dermis. ~dermis consists of supportive connective tissue mainly collagen elastin and glycosaminoglycans. ~Dermis has resident population of fibroblast lymphocytes and dermal dendritic cells. ~Sabcutis the lowermost layer has a plexus of nerves and vessels. ~appendages of skin include hair sweat glands and sebaceous glands. ~skin has extensive nerve network with specialised endings in the papillary dermis. ~vessels in skin run-up parallel to each other and former superficial plexus of vessels in papillary dermis lymphatics drain to regional lymph nodes.