Library · Physiology
Skin renewal
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The skin you touch today is not the same skin you have always had. The epidermis, which is the outermost layer, renews itself nonstop, and it does so from below: in the basal layer, the deepest level, there are stem cells that divide constantly and keep turning out new keratinocytes, the most abundant cells in the skin.
Each keratinocyte is born at the bottom and travels toward the surface. As it rises it keeps changing, and the change ends in dramatic fashion: it loses its nucleus. What is left is called a corneocyte, and inside it is little more than filaments of keratin, the tough protein of skin and nails, embedded in a matrix of filaggrin.
Those stacked corneocytes make up the stratum corneum, the outer layer. And that is where the story ends: when they lose the adhesion that holds them together, they come loose and flake off. Those corneocytes are what your skin leaves on the towel.
It is a wall that is built from the bottom and crumbles at the top.
In brief
The skin renews itself from below: in the basal layer there are constantly dividing stem cells that produce new keratinocytes.
A wall that builds itself from the bottom while it crumbles at the top.
Each keratinocyte moves up and differentiates until it becomes a corneocyte, a keratinocyte with no nucleus whose keratin filaments sit in a matrix of filaggrin.
Corneocytes form the stratum corneum, and when they lose their grip on one another they flake off.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Skin (Integument), Epidermis, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingHistology, Stratum Corneum, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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