We propose to upgrade the Laser-scanning Confocal Microscopy Facility now offered as one of the shared resources in the Developmental Biology Center, an Organized Research Unit of the University of California. We will upgrade our existing MRC600 to the MRC1000 confocal microscope, add a UV laser and install the upgraded system on an inverted microscope. This will provide us with the capability of imaging three, rather than two, fluorescent probes as well as a transmitted light image, and to use UV- excited dyes. The major users will use this equipment to extend their ongoing studies of Drosophila telomere structure and function, the structure and function of apical cell junctions in Drosophila imaginal discs, the role of the dishevelled gene product in wingless signalling in Drosophila, the lineage relationships of interstitial cells in hydra, the migration, lineage and regenerative properties of neural crest cells in chick embryos, and the analysis of proteins that support the survival and regeneration of neurons from adult mammals. The three-signal capability as well as the UV laser will make possible new imaging combinations that will provide new insights into developmental mechanisms at many different levels. The equipment will also be made available to other users as instrument time permits.