A confocal and conventional epifluorescence microscope study of the intermediate filaments in chorionic villi.

An immuno-epifluorescence microscopic study of first trimester human chorionic villi has revealed different patterns of distribution for intermediate filament proteins. Keratin staining was restricted to the trophoblastic epithelium. The protein was shown to be concentrated into desmosome-containing apical and basal cytoplasm. Strands of keratin-rich cytoplasm extended across the interior of the syncytium, integrating basal and apical layers. This arrangement integrates the epithelial cytoskeleton in a manner well adapted to resisting shearing forces. Vimentin was found in the cells of the villous core and was most strongly expressed in endothelial cells. Desmin was also restricted in distribution of spindle-shaped cells of the villous core. It was excluded from terminal villi.