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The human stratum corneum comprises several levels of flattened corneocytes that are divided into two layers: the stratum disjunctum and stratum compactum. 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.
During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum. Corneocytes are keratinocytes that have completed their ...
Keratinocytes in the stratum basale of the epidermis will multiply through cell division and migrate toward the skin surface. During that migration keratinocytes will undergo multiple stages of differentiation to finally become corneocytes once they reach the stratum corneum.
Keratinocytes are the main cell type of the epidermis. They form several layers of the skin. Life for a keratinocyte begins at the stratum basale layer. Cells here proliferate and move through the stratum spinosum and stratum granulosum. The topmost layer is called the stratum corneum. During sloughing, it is this layer that is removed. [1]
In the upper stratum spinosum and stratum granulosum layers of the epidermis, lamellar bodies are secreted from keratinocytes, resulting in the formation of an impermeable, lipid-containing membrane that serves as a water barrier and is required for correct skin barrier function.
Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratinocytes reside in the basal, spinous, or granular layers of the epidermis. The outermost layer of the epidermis is called the stratum corneum and it is composed of terminally differentiated keratinocytes, the corneocytes.
Keratinocyte differentiation throughout the epidermis is in part mediated by a calcium gradient, increasing from the stratum basale until the outer stratum granulosum, where it reaches its maximum, and decreasing in the stratum corneum. Calcium concentration in the stratum corneum is very low in part because those relatively dry cells are not ...
It is now understood that this is not true, and that the stratum corneum should be considered to be a live tissue. [10] While it is true that the stratum corneum is mainly composed of terminally differentiated keratinocytes called corneocytes that are anucleated, these cells remain alive and metabolically functional until desquamated. [citation ...