General Structure of Skin, Oral and Junctional Epithelia

General Structure of Skin, Oral and Junctional Epithelia 

A basal lamina is permeable to interstitial fluid which provides the nutrients for the basal layer of cells to proliferate. As discussed in Sect. 5.1, basal cells adhere to the basal lamina using hemidesmosomes. In simple epithelia, basal cells either divide into identical daughter cells or undergo apoptosis (programmed cell death, Sect. 13.4.1). In a stratified 

The keratin family of proteins comprises two of the six classes of intermediate filament proteins found in the cytosol of eukaryotic cells. They provide the intracellular structural stability that complements the intercellular mechanical cohesion provided by desmosomes. Keratin filaments cross the entire cytosol of keratinocytes and their ends are tightly attached to desmosomes by desmoplakin (Fig. 5.9) or, in basal cells, to the related plakin (BP230) and plectin proteins in hemidesmosomes. 

Note Keratin is an intracellular filamentous protein whereas keratan is a sulfated polysaccharide found extracellularly in cartilage and dermal (stromal) connective tissue. 

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