Exacerbated brain tissue destruction and neuronal cell death in head-injured CD59-/- mice. Microphotographs show adjacent cryosections of 8 μm thickness of left (injured) brain hemispheres harvested at 24 h after closed head injury each from a representative wild-type (upper panel) and a CD59a-/- (lower panel) mouse. Cellular signals were visualized by fluorescence microscopy. The left columns represent the DAPI nuclear stain which reveals the cellular distribution and morphology of all cells present in the resultant sections. TUNEL histochemistry was performed on adjacent sections (right columns) to reveal the distribution and morphology of cell death. TUNEL-positive cells were mainly detected within the contusion zone of head-injured wild-type mice. In contrast, the number of TUNEL-positive cells was clearly augmented in the contusion zone of CD59a-/- mice, and remote cell death was detected in cortical layers of the ipsilateral hemisphere and in the hippocampus. Neurons were identified as the main cellular source of TUNEL-positive cell types by immunostaining of adjacent brain sections using anti-NeuN as primary antibody, a neuron-specific cell marker (bottom panels). Uninjured, i.e. sham-operated or untreated, CD59-/- mice did not show any positive TUNEL signals in brain sections (data not shown). These data imply an increased amount of cell death and tissue destruction in brain-injured CD59-/- mice, compared to wild-type animals. Original magnifications: 100×.