«Introduction: the epidermis
As they pass through the various layers of the epidermis, the keratinocytes differentiate, undergoing numerous modifications.
Initially, keratin filaments are formed, that filamentous protein that begins to be produced already in the spiny layers of the epidermis and which is part of the constitution of hair and nails. In the overlying layer, called granulose, there are Odland granules or lamellar bodies that , located between the various keratinocytes, release lipids into the extracellular space.
During the ascent the nucleus and the various cytoplasmic organelles also disappear. The keratoyalin granules, typical of the granular layer, are also missing.
Keratoyalin is a mixture of various substances, including profilaggrin, a protein that is dephosphorylated to filaggrin, which functions as a mechanical support for the assembly of the keratin filaments. In this way, macrofibrils are formed, a kind of cord. of keratin resting on the filaggrin.
In addition to these macrofibrils, there are also low molecular weight keratins, non-fibrous and rich in sulfur, which form an amorphous matrix interposed with them.
Once this support function has been carried out, filaggrin is degraded into the various amino acids (see below).
CONTINUE: skin and dehydration "
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