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Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae. [7] Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. The epidermis itself has no blood supply and is nourished almost exclusively by diffused oxygen from the surrounding air. [8]
Rete pegs (also known as rete processes or rete ridges) are the epithelial extensions that project into the underlying connective tissue in both skin and mucous membranes. In the epithelium of the mouth, the attached gingiva exhibit rete pegs, while the sulcular [ 2 ] and junctional epithelia do not. [ 3 ]
Pig skin especially shares similar epidermal and dermal thickness ratios to human skin: pig and human skin share similar hair follicle and blood vessel patterns; biochemically the dermal collagen and elastin content is similar in pig and human skin; and pig skin and human skin have similar physical responses to various growth factors. [1] [2]
The dermis is composed of three major types of cells: [3] fibroblasts, macrophages, and mast cells.. Apart from these cells, the dermis is also composed of matrix components such as collagen (which provides strength), elastin (which provides elasticity), and extrafibrillar matrix, an extracellular gel-like substance primarily composed of glycosaminoglycans (most notably hyaluronan ...
In a growing fetus, fingerprints form where the cells of the stratum basale meet the papillae of the underlying papillary layer of the dermis, resulting in the formation of the ridges on the fingers. Fingerprints are unique to each individual and are used for forensic analyses because the patterns do not change with the growth and aging processes.
The dermal papillae between the elongated rete ridges are frequently dome shaped. Necrotic keratinocytes can be observed in the basal layer of the epidermis and at the dermal-epidermal junction. Eosinophilic remnants of anucleate apoptotic basal cells may also be found in the dermis and are referred to as “colloid or civatte bodies”.
The apical ectodermal ridge (AER) is a structure that forms from the ectodermal cells at the distal end of each limb bud and acts as a major signaling center to ensure proper development of a limb. After the limb bud induces AER formation, the AER and limb mesenchyme —including the zone of polarizing activity (ZPA)—continue to communicate ...
In the finger pads, sweat glands pores are somewhat irregularly spaced on the epidermal ridges. There are no pores between the ridges, though sweat tends to spill into them. [20] The thick epidermis of the palms and soles causes the sweat glands to become spirally coiled. [2]