Nicotinamide-adenine-dinucleotide-phosphate diaphorase-positive neurons and fibers in the nucleus olfactorius anterior of the rat.

The distribution patterns of NADPH-diaphorase activity in the nucleus olfactorius anterior (NOA) and anterior commissure (AC) of the rat were described using an histochemical technique. In the lateral, dorsal, ventral, medial and posterior subdivisions of the NOA we have demonstrated heavily stained elements (neurons and processes), and slightly labelled cell bodies. The neurons were mainly located in the inner zone of these subdivisions. However, in the external subdivision (NOAe) strongly stained fibers and weakly labelled cell bodies were present. The NOA transitions areas showed the same NADPH-diaphorase activity distribution patterns as those of the corresponding NOA subdivisions. In the AC we described scarce NADPH-diaphorase positive fibers parallelly oriented to the unstained commissural fibers, and scattered stained neurons.