Actin in stratified squamous keratinized epithelium

Actin filament distribution patterns were revealed in a stratified squamous keratinized epithelium using phalloidin-fluorescent and immunogold labeling techniques applied on bovine ruminal pilar as a model tissue. In non-keratinized cell types, actin concentrates on the microfilament-rich cellular cortex as well as on cytoplasmic processes and protrusions. In cornified cells labeling is distributed diffusely over the amorphous cytoplasm. A constant feature in all cell types is plasmalemmal labeling. Desmosomes exhibit deposition on their plasmalemmal leaflets, the dense central stratum and plaques. Desmosomal as well as cytoplasmic keratin filament bundles also label for actin, the latter often in a cross-banded manner. These cellular distribution patterns of actin filaments are discussed with respect to the significance of the microfilaments in the process of cell shape determination, stratification, and cell adhesion.