Topographical organization of NADPH-diaphorase positive neurons and fibres in dorsal ponto-mesencephalic tegmentum in the rat brain.

20 complete series of the rat brain, stained with cresylviolet or with the NADPH-diaphorase positive neurons demonstration method were used to compare the topographical organization of the borders of the dorsal mesopontine tegmental nuclei (latero-dorsal tegmental nucleus, dorsal and ventral tegmental nuclei of Gudden, dorsal raphe nucleus and substantia grisea centralis pontis) and to describe in detail NADPH-d positive cells and fibres in this area. We have found that topography of the cells and the borders of the nuclei were similar by the both methods, but NADPH-d histochemistry has shown the extension of NADPH-d positive cells to neighbouring structures and we would divide some nuclei into independent parts (e.g., pars medialis, ventralis and rostralis of the laterodorsal tegmental nucleus). We discussed the possibility of the projection and configuration of NADPH-d positive fibres running from the mesopontine tegmentum to the diencephalon.