The main purpose of the core unit is to characterize and localize transcripts of novel genes generated by genetic screens for cardiac and CNS development mutants by the investigators participating in the Cooperative Grant. The two main methods the core unit will be applying are in situ hybridization on whole-mounts and or tissue sections. Both normal and mutant embryos will be examine. In some cases, hearts will be dissected out, and analyzed as the organ alone. Whole-mount methods are especially useful for the analysis of early embryos since this procedure allows visualization for complex expression patterns in time and space. Sections are useful for detailed correlations between the histology and sites of gene expression. Gene chip core facility will also assist the investigators in analyzing and interpreting the histological and gene expression data, help them to identify specific cell types by means of cell specific markers and the cases where developmental problems are being addressed. Dr. Schwartz and collaborators will assist in exploring the developmental context. It will also be the responsibility of the core unit to document the findings in the form of video prints, black and white or color prints or slides, and picture files that can be accessed through the world via Internet.