NADPH-diaphorase-positive neurons and pathways in the brain of the frog Rana esculenta

We described the NADPH-diaphorase-containing neurons and fibres in the brai n of the frog Rana esculenta. In the telencephalon stained cells occurred i n the olfactory bulb, all subdivisions of the pallium, the diagonal band, t he medial septum and the striatum. The olfactory glomeruli showed the most intense enzyme reaction. The neuropil of the accessory olfactory bulb was a lso heavily stained and this staining extended to the rostral diencephalon through the ventral lateral pallium. Fibre staining was less intense in the medial pallium and the medial septum. In the diencephalon, NADPH-diaphoras e staining was concentrated in the middle third of this part of the brain. The stained cells were embedded in a dense network of thin, stained fibres and terminals in the lateral anterior and central thalamic nuclei. Faintly stained cells were present also in the posterior preoptic nucleus, anterior thalamic nucleus, nucleus of Bellonci, corpus geniculatum thalamicum and t he suprachismatic nucleus. In the mesencephalon, heavily stained cells occu rred in the nucleus profundus mesencephali, anterodorsal, anteroventral and especially in the posterodorsal tegmental nuclei. Neuronal staining was le ss intense in the optic tectum and the torus semicircularis. Thick, intense ly stained fibres occupied the lateral part of the tegmentum and the 7th la yer of the tectum. A loose network of thin fibres occupied the periventricu lar area and all tegmental nuclei. In the rhombencephalon, the reticular nu clei and the inferior raphe nucleus showed the most intense staining, while some cells in the nucleus of the solitary tract and the dorsal column nucl ei were less intensely stained. Heavy staining of fibres was characteristic of the spinal trigeminal tract, the solitary tract and the reticulospinal pathway.