FIRST Flashcard Word of the Month: Desquamation
What is Desquamation?
The epidermis is a self-renewing system. Old cells (or ‘squames’) are shed from the skin surface as new cells (‘keratinocytes’) are produced, in the underlying epidermis, and pushed outward into the stratum corneum (the outer most layer of the epidermis) to become ‘corneocytes’. This process is known as desquamation.
In the recent past, it was thought that the process of desquamation initiated the progressive breakdown (‘proteolysis’) of proteins forming structures, called ‘corneodesmosomes’. These protein forming structures link adjacent ‘corneocytes’ to one another. We now know this prior model does not fully account for desquamation, because the cells detach well above the sites where these junctions are degraded. In other words, proteolysis of corneodesmosomes may be necessary for desquamation, but it is not sufficient to complete the entire shedding process.
Instead, recent studies show that cells detach following hydration. Water swells the extracellular spaces and separates adjacent corneocytes. As the water evaporates from between corneocytes, it is replaced by air, which eventually allows individual cells to detach from the skin surface.
What does this mean for the ichthyosis community?
There’s no question – for those affected by ichthyosis, frequent bathing is now even more important, as it is not only the best way, but the most natural way to remove dry scales and skin – and, most importantly, more frequent bathing can ease the distress of ichthyosis, making day to day life much more comfortable.
Resource: Peter M. Elias, MD http://eliasandwilliams.com/what-allows-skin-to-shed/
For more information on the permeability barrier, the most critical, life-enabling function of skin, visit the FIRST page on the Inside Out of Skin a groundbreaking website developed by Peter M. Elias, MD, and Mary L. Williams, MD.
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