SEPARATION OF GERM-CELL APOPTOSIS FROM TOXIN-INDUCED CELL-DEATH BY NECROSIS USING IN-SITU END-LABELING HISTOCHEMISTRY AFTER GLUTARALDEHYDE FIXATION

In situ end-labeling of fragmented DNA is routinely being used to dete ct apoptotic cells in various tissues including the testis, In this st udy, we examined the influence of various fixatives (neutral buffered formalin, paraformaldehyde, and glutaraldehyde) on the testicular stru ctural integrity and the immunoreactivity of fragmented DNA in apoptot ic germ cells of the adult rat, Accelerated apoptosis of germ cells wa s induced in the adult rat by gonadotropin deprivation, Visualization of apoptotic DNA fragmentation in individual germ cells was achieved b y direct immunoperoxidase detection of digoxigenin-labeled genomic DNA , Glutaraldehyde fixation significantly improved the in situ detection of apoptotic germ cells while maintaining excellent morphological pre servation, The labeling is also specific for apoptosis since necrotic germ cells show no specific signals, Fixed tissues could be processed for electron microscopy for further characterization of germ cell deat h using morphological criteria, Thus, glutaraldehyde fixation is advan tageous for recognition of apoptotic germ cells with high sensitivity and specificity on a cell-by-cell basis, It should also be applicable to detect apoptosis in other cells and tissues.