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Kal-El can lead an alter ego as Clark Kent because Kryptonians appear identical to humans. Also, in both Silver Age and Modern Age continuity, Kryptonians have more than one ethnic group, such as dark-skinned Kryptonians from Krypton's Vathlo Island that resemble Earth humans of Sub-Saharan African, Negrito, Melanesian, and Indigenous Australian descent and a group from the continent of Twenx ...
One average square inch (6.5 cm 2) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than 1,000 nerve endings. [5] [better source needed] The average human skin cell is about 30 μm in diameter, but there are variants. A skin cell usually ranges from 25 to 40 μm 2, depending on a variety of factors.
The cells in the stratum granulosum do not divide, but instead form skin cells called keratinocytes from the granules of keratin. These skin cells finally become the cornified layer ( stratum corneum ), the outermost epidermal layer, where the cells become flattened sacks with their nuclei located at one end of the cell.
Micrograph of keratinocytes, basal cells and melanocytes in the epidermis Keratinocytes (stained green) in the skin of a mouse. Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. [1]
Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface.
The word skin originally only referred to dressed and tanned animal hide and the usual word for human skin was hide. Skin is a borrowing from Old Norse skinn "animal hide, fur", ultimately from the Proto-Indo-European root *sek-, meaning "to cut" (probably a reference to the fact that in those times animal hide was commonly cut off to be used as garment).
These stem cells develop into both keratinocyte precursors and melanoblasts - and these melanoblasts supply both hair and skin (moving into the basal layer of the epidermis). There is additionally evidence that melanocyte stem cells are present in cutaneous nerves, with nerve signals causing these cells to differentiate into melanocytes for the ...
The skin's protective acid mantle and lipid barrier sit on top of the stratum disjunctum. [5] The stratum disjunctum is the uppermost and loosest layer of skin. The stratum compactum is the comparatively deeper, more compacted and more cohesive part of the stratum corneum. [ 6 ]