A simple and rapid method for the identification of cycling cells in freshly excised tumours.

Cytogenetic studies of fresh solid tumours are hampered by the small numbers of poor quality metaphases which are obtained through direct preparations. The proportion of cycling cells in freshly excised tumours have been identified by measuring the incorporation of the nucleoside analogue 5-bromo-2'deoxyuridine (BrUdR) into DNA. We have developed an immunochemical method using a mouse monoclonal antibody directed against BrUdR which stains nuclei of cells which have incorporated this nucleoside. Using this method, optimal culture conditions and harvest times may be identified, to provide greater numbers of high quality metaphases, suitable for karyotyping solid tumours.