Reduced nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry in the pontomesencephalic region of the human brainstem.

Reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase), which is specifically localized in neurons, has been histochemically demonstrated in human brain by using a perfusion-fixation procedure. With such fixed human brainstem, it was possible to study the topographic organization of NADPH-diaphorase-containing neurons that were visualized in fine detail for the first time. In the pontomesencephalic region, positive neurons were observed in nuclei around the decussation and arm of the superior cerebellar peduncle. These nuclei included the pedunculopontine tegmental, lateral parabrachial and oral pontine reticular nuclei. The positive somata were mainly multipolar in shape and medium to large in size. The positive neurons appeared to correspond to cholinergic neurons, at least partly in the brainstem, in terms of both the patterns of distribution and the cellular morphology.