Topographical distribution of NADPH-diaphorase positive neurons in the cat's inferior colliculus.

By using a histochemical procedure NADPH-diaphorase the topographical distribution of neurons and fibers containing NADPH-diaphorase activity in the cat's inferior colliculus is examined. Neurons and fibers positive for NADPH-diaphorase are observed throughout the rostro-caudal extent of the inferior colliculus, located in its three main subdivisions: nucleus centralis, nucleus pericentralis and nucleus externus. According to the size of the perikarya, dendritic and axonal morphology the positive neurons are classified as follows: large, medium-sized and small. The morphological differences could contribute to the different functions of these cells. The results support the hypothesis that large and medium-sized NADPH-diaphorase positive neurons represent the projections neurons while the small NADPH-diaphorase positive neurons have morphological characteristics that corresponds to the interneurons. Finally, results demonstrating existence of dense network of NADPH-diaphorase positive fibers and fragments suggest that they are dendrites and axons of NADPH-diaphorase positive neurons distinguished in inferior colliculus.