The fluorescence imaging core will provide Harvard Skin Disease Research Center investigators with high resolution localization of fluorescent probes in cells and tissues derived from normal and pathologic materials. Detection of immunofluorescence labels, fluorescent vital dyes and fluorescent fusion proteins are of interest to investigators with diverse experimental approaches that lack expertise in imaging methods.Investigators will be provided with state of the art techniques in biological microscopy including: confocal and multiphoton imaging and fluorescence resonance energy transfer (FRET). Consultative services will be available for immunocytochemistry, in situ hybridization and electron microscopy. The specific aims of the core are: 1) To provide confocal imaging of live and fixed cells and tissues; allowing the determination of multiple probes within three dimensional organization of cells or tissue and analyzing changes in that distribution over time. 2) To provide multiphoton illumination for imaging of fluorescent probes in live cells, thick tissues or other cases where traditional single photon excitation is insufficient to address investigators' questions. 3) To prbvide fluorescence resonance energy transfer analysis of protein-protein interactions using confocal, multiphoton or wide-field illumination. 4) To provide in-situ hybridization and electron microscopy techniques on a consultative basis. The core contains the necessary equipment, reagents and expertise to conduct advanced biological microscopy experiments. The director and assistant are readily available to advise investigators on all aspects of biological microscopy, fluorescence detection and quantitative imaging.