The deeper reticular layer consists of dense, irregular connective tissue with fibroblasts, type I collagen, and thick elastic fibers. The superficial papillary layer (i.e., the dermal papillae) consists of loose connective tissue with fibroblasts, types I and Ill collagen fibers, and thin elastic fibers. The dermis is composed of the papillary layer and reticular layer. Dermis: The junction between the epidermis and dermis is irregular, whereby epidermal ridges protrude into the underlying dermis, and dermal papillae protrude into the overlying epidermis (see Fig. DER = dermis,DP = dermal papillae, EPI = epidermis,ER = epidermal ridge, HF = hair follicle,SBG = sebaceous gland.Ģ. AD = adipose tissue,DER = dermis, DP = dermal papillae, EPI = epidermis, ER = epidermal ridge, ESD = eccrine sweat gland duct, ESG = eccrine sweat gland, HYP = hypodermis, PC = Pacinian corpuscle.įigure 2: Thin skin.
#TRANSLUCENT CELLS CONTAINING KERATIN FIBRILS SKIN#
On the basis of the comparative thickness of the epidermis, skin is classified as either thick skin (found on palms of the hands or soles of the feet) or thin skin (covering the rest of the body), as shown in Figures 1.
Outer epidermis: The outer epidermis is an epithelial layer classified as a keratinized stratified squamous epithelium. In general, skin consists of three layers, outer epidermis, middle dermis, and deep hypodermis or subcutaneous layer.ġ. Epidermal derivatives include sweat and sebaceous glands, hair and hair follicles, and nails.Ĭollectively, skin and epidermal derivatives regulate body temperature and water loss, provide a nonspecific barrier to external environmental factors (e.g., microorganisms), synthesize vitamin D, absorb ultraviolet (UV) irradiation, convey sensory information, play a role in antigen presentation, and secrete sweat and sebum. Skin forms the outer covering of the body and is the largest organ of the body, accounting for 15%-20% of the total body weight.
The integumentary system consists of the skin and epidermal derivatives (or epidermal appendages).
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