Since the primary thrust of this program project centers on keratinocyte differentiation, each of the projects will utilize the Morphology Core for various types of morphological assays. Cultures analyzed biochemically also will be assessed morphologically to correlate functional results with light microscopic and ultrastructural criteria of differentiation. Moreover, the Morphology Core will be used to establish the purity of cell samples and subcellular fractions, as well as the presence of 3T3 cell or fibroblast contamination. Finally, the Morphology Core will utilize its light/phase/fluorescence photomicroscopy unit to assist investigators with immunofluorescence, fluorescence tracer studies (for ionic calcium and proton determinations), and phase contrast monitoring of subcellular fractions and liposome preparations.