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In the human skin, the dermal papillae (DP) (singular ''papilla'', diminutive of Latin ''papula'', 'pimple') are small, nipple-like extensions (or interdigitations) of the dermis into the epidermis. At the surface of the skin in hands and feet, they appear as epidermal or papillary ridges (colloquially known as fingerprints). Blood vessels in the dermal papillae nourish all hair follicles and bring nutrients and oxygen to the lower layers of epidermal cells. The pattern of ridges they produce in hands and feet are partly genetically determined features that develop before birth. They remain substantially unaltered (except in size) throughout life, and therefore determine the patterns of fingerprints, making them useful in certain functions of personal identification. 〔(【引用サイトリンク】 title = Dermal papillae )〕 The dermal papillae are part of the uppermost layer of the dermis, the papillary dermis, and the ridges they form greatly increase the surface area between the dermis and epidermis. Because the main function of the dermis is to support the epidermis, this greatly increases the exchange of oxygen, nutrients, and waste products between these two layers. Additionally, the increase in surface area prevents the dermal and epidermal layers from separating from each other by strengthening the junction between them. With age, the papillae tend to flatten and sometimes increase in number. 〔(【引用サイトリンク】 title = Friction Skin )〕 Dermal papillae also play a pivotal role in hair formation, growth and cycling. In mucous membranes, the equivalent structures to dermal papillae are generally termed "connective tissue papillae", which interdigitate with the rete pegs of the superficial epithelium. ==See also== * Papilla (disambiguation) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「dermal papillae」の詳細全文を読む スポンサード リンク
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