IN-SITU END LABELING WITH BROMODEOXYURIDINE - AN ADVANCED TECHNIQUE FOR THE VISUALIZATION OF APOPTOTIC TELLS IN HISTOLOGICAL SPECIMENS

The fragmentation of nuclear DNA is considered to be a biochemical ind ication of programmed cell death (PCD) in various tissues. Several lig ht microscopical approaches have been employed for the visualization o f such fragmentation and have used either in-situ nick end labelling ( ISEL) or in-situ nick translation (ISNT) whith labelled dUTP. In the c urrent paper, we can report a new method in which 0.5 mu m Epon sectio ns of mouse jejunum were incubated with terminal deoxynucleotidyl tran sferase (TdT) and 5-bromo-2-deoxyuridine (BrdU) for the in-situ tailin g of fragmented DNA. Anti BrdU and the peroxidase anti peroxidase meth od (PAP) were used for staining the reaction product. Semithin section s of jejunum revealed high resolution images of labelled nuclei in the intestinal mucosa. An examination with confocal laser scanning micros copy indicated the differential distribution of immunoprecipitates in cellular nuclei, perhaps representing those distinct levels of DNA cle avage that may characterise the discrete stages of apoptosis. This new method is likely to offer new possibilities for the high resolution i maging of PCD, including the assessment of time courses and apoptosis statuses in histochemically characterized cells.