Dermis Research Paper
The dermis is the tough fibrous layer of the skin lying between the epidermis and the subcutaneous tissues. It consists of a variable type of fibrous connective tissue which cushions the body from stress and strain. Also, the dermis provides tensile strength and elasticity to the skin through its dermal fibres (collagen, reticular, and elastic fibres) that are embedded in an extrafibrillar matrix [72, 73]. The dermis is approximately 15 to 40 times thicker than the epidermis and can be further divided into a superficial part adjacent to the epidermis, the papillary dermis, and a deep thicker part, the reticular dermis. The papillary dermis interdigitates with the epidermis and is mostly composed of loosely arranged thin collagen fibres, whereas
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Collagen fibres are composed of aggregations of thinner fibrils that have a diameter of 100nm to 500 nm and cross striations that repeat at intervals of 60 nm to 70 nm. These fibrils when aggregated with glycoproteins become collagen fibres that in turn form collagen bundles ranging from 2µm to 15 µm in diameter [86]. In general, collagen in the primary insoluble fibrous proteins in connective tissues and the ECM [87]. At least 16 subtypes of collagen have been identified in the human body, and 80-90% of the body collagen consists of types I, II and III [88]. The basic structural unit of all collagen types is a triple-helical structure made of three subunits: two α1chains and one α2 chain. The unique properties of each collagen subtype mainly arise from segments interrupting the helical structure, which fold the collagen into other kinds of three-dimensional structures [87]. Table 2.3 summarized the major collagen subtypes present in the human body [88, 89]. In the dermis, collagen type I and collagen type III (also known as reticular fibres) represent about 80%, and 15% of the collagen fibres, respectively. While, most of the remainder fibres are thought to be of collagen type V. Collagen types IV, VII and XVII are mainly located in the basal membranes beneath the basal epithelial cells of the
Collagen fibres are composed of aggregations of thinner fibrils that have a diameter of 100nm to 500 nm and cross striations that repeat at intervals of 60 nm to 70 nm. These fibrils when aggregated with glycoproteins become collagen fibres that in turn form collagen bundles ranging from 2µm to 15 µm in diameter [86]. In general, collagen in the primary insoluble fibrous proteins in connective tissues and the ECM [87]. At least 16 subtypes of collagen have been identified in the human body, and 80-90% of the body collagen consists of types I, II and III [88]. The basic structural unit of all collagen types is a triple-helical structure made of three subunits: two α1chains and one α2 chain. The unique properties of each collagen subtype mainly arise from segments interrupting the helical structure, which fold the collagen into other kinds of three-dimensional structures [87]. Table 2.3 summarized the major collagen subtypes present in the human body [88, 89]. In the dermis, collagen type I and collagen type III (also known as reticular fibres) represent about 80%, and 15% of the collagen fibres, respectively. While, most of the remainder fibres are thought to be of collagen type V. Collagen types IV, VII and XVII are mainly located in the basal membranes beneath the basal epithelial cells of the