Epidermal architecture

In some cases the epidermal architecture was recorded quantitatively by determining,... 

The epidermal layers are dissolved down to the basal layer in 24—36 hours under an occlusive mask. Thereafter, the architecture of the cells returns to normal and the histological coloring evens out. After a peel, the palisade structure of the keratinocytes is more even. 

Van Scott and Ekel in 1963 (V4) studied epidermal cell kinetics by projecting histologic sections of lesions. They traced the architecture of the epidermis, counted the number of mitoses present, and determined the relationship of the proliferative cell population to the skin surface, to the viable epidermal cell population, and to the epidermis as a whole. This was repeated in from 6 to 24 sequential 8-/t-thick sections, and a... 

The basement membrane zone or epidermal-dermal junction is a thin extracellular matrix that separates the epidermis from the dermis. It is a highly specialized structure recognized with the light microscope as a thin, homogeneous band. Ultra-structurally, it can be divided into four component layers (1) the cell membrane of the basal epithelial cell, which includes the hemidesmosomes (2) the lamina ludda (lamina rara) (3) the lamina densa (basal lamina) and (4) the subbasal lamina (sublamina densa or reticular lamina), with a variety of fibrous structures (anchoring fibrils, dermal microfibril bundles, microthreadlike filaments) (Briggaman and Wheeler, 1975). The basement membrane has a complex molecular architecture with numerous components that play a key role in adhesion of the epidermis to the dermis. The macromolecules that are ubiquitous components of all basement membranes... 

Figure 18.1 Histological architecture of skin showing epidermal and dermal layers and...

One form of cellular demise common to epithelial cells is detachment-initiated apoptosis, also referred to as anoikis (Frisch and Francis, 1994). Epidermal keratinocytes rely on signals derived from the surrounding extracellular matrix for survival. It is possible that loss of these signals plays a role in SM-induced epidermal cell injury, and that cell detachment from the basal lamina precedes cytotoxicity. Several lines of evidence support this possibility. First, SM can alter the dynamics of cytosolic proteins that exert control over the attachment of cells to the basement membrane. For example, SM can modify intracellular actin microfilaments and keratin intermediate filaments known to be important in maintaining epithelial cell connections with the basal lamina. Thus, Hinshaw et al. (1999) reported that SM causes changes in the actin microfilament architecture and morphology of human keratinocytes within 3h of... 

Prekeratin is the protein of the epidermal tonofilaments and the bovine material has now been characterized in some detail Many features of its molecular architecture are known and, most importantly for the purposes of this study, it has been shown to consist of three different polypeptide chains which can be readily detected on sodium dodecyl sulphate (SDS)-polyacrylamide gels. 

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