Basement Membrane Zone (BMZ)
Many stratified squamous epithelial
tissues, such as the skin and oral mucosa, contain a complex Basement Membrane
Zone (BMZ). The BMZ is composed of
many specialized components which combine to form anchoring complexes.
At the superior aspect of the BMZ,
keratin-containing intermediate filaments of the basal cell cytoskeleton insert
on basal cell plasma membrane condensations termed ‘hemidesmosomes’. Anchoring filaments extend from the basal cell
plasma membrane into the extracellular environment and span the lamina lucida,
connecting hemidesmosomes with the lamina densa.
At the most inferior aspect of the
BMZ, type VII collagen-containing anchoring fibrils extend from the lamina densa
into the papillary dermis connecting the lamina densa to anchoring plaques,
trapping interstitial collagen fibrils. Thus, the cutaneous BMZ connects the
extensive basal cell cytoskeletal network with the abundant network of
interstitial collagen fibrils in the dermis.
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