This project is directed at refining, adapting, and developing technologies for purposes of supporting morphologically based research. It is primarily technology development rather than exclusively hypothesis based research and has application to research throughout DIR. Our aim is to make the technology serve research - and not to engage in technology driven activities. We serve as an intellectual resource for NIEHS investigators and only perform technical tasks as full research collaborators. Examples of recent efforts include: (1) development of image analysis procedures for epidermal carcinogenesis studies, (2) establishing methods for estimating the number of hepatocytes in the livers of rodents treated with different xenobiotics, (3) development of a methods for estimating cellular ploidy from two-dimensional histologic sections, (4) development and application of easier techniques for identifying cells in different phases of the cell cycle and for quantitating these, (5) stereological measurement of preneoplastic lesions as predictors of hepatocarcinogenicity, (6) development of non-radioactive in-situ hybridization procedures for histones, lactoferrin, WT-1, and BRCA 1 & 2 in archival tissue specimens,(7) flow cytometry work to help quantitate apoptosis in liver, (8) stereology on lung tumors (measurement of lung tumor sizes), and (9) development of computer assisted image analysis to quantitate BrdU stained S-phase cells.