To understand how the skin barrier works, we need to return to our ‘bricks and mortar’ model of the outermost layers of the epidermis, the ‘stratum corneum.’ In this layer, the cells (called ‘corneocytes’) no longer possess a nucleus – they are essentially dead. But they are filled with tough, fibrous proteins, called ‘keratins,’ and many small molecules derived from the breakdown of proteins and other components of these once-living cells.
Simply stated, the bricks (or corneocytes) provide a durable defense against the ordinary frictional wear and tear of life.
As long, protein polymers, it is the keratins that give the skin much of its remarkable mechanical strength. Another contributor to its strength is another protein structure, the so-called ‘cornified envelope.’ This polymer is made up of several different protein precursors. It surrounds the corneocyte, rather like a hedgerow of rose bushes, and replaces the cell membrane of the former, living cell. [Read more…] about How The Skin Barrier Works