NADPH-diaphorase activity in area 17 of the squirrel monkey visual cortex: neuropil pattern, cell morphology and laminar distribution

Abstract

We studied the distribution of NADPH-diaphorase activity in the visual cortex of normal adult New World monkeys (Saimiri sciureus) using the malic enzyme "indirect" method. NADPH-diaphorase neuropil activity had a heterogeneous distribution. In coronal sections, it had a clear laminar pattern that was coincident with Nissl-stained layers. In tangential sections, we observed blobs in supragranular layers of V1 and stripes throughout the entire V2. We quantified and compared the tangential distribution of NADPH-diaphorase and cytochrome oxidase blobs in adjacent sections of the supragranular layers of V1. Although their spatial distributions were rather similar, the two enzymes did not always overlap. The histochemical reaction also revealed two different types of stained cells: a slightly stained subpopulation and a subgroup of deeply stained neurons resembling a Golgi impregnation. These neurons were sparsely spined non-pyramidal cells. Their dendritic arbors were very well stained but their axons were not always evident. In the gray matter, heavily stained neurons showed different dendritic arbor morphologies. However, most of the strongly reactive cells lay in the subjacent white matter, where they presented a more homogenous morphology. Our results demonstrate that the pattern of NADPH-diaphorase activity is similar to that previously described in Old World monkeys. Correspondence

Neuropil reactivity, distribution and morphology of NADPH diaphorase type I neurons in the barrel cortex of the adult mouse

“…white matter was elongated in an axis parallel to the border with the gray matter, especially when located close to it (data not illustrated). This bias was also found in other species such as the rat (Freire et al, 2004) and the squirrel monkey (Franca et al, 1997).…”

“…We did not find type II cells in the white matter, a finding also reported for other mammalian species (Sandell, 1986;Franca et al, 1997Franca et al, , 2000Freire et al, 2004). Due to both their weaker pattern of reactivity and susceptibility to increased levels of fixation (Sandell, 1986;Franca et al, 2000), type II cells were not quantified in this study.…”

“…Type II neurons have been found in the isocortex of many other mammalian species, from marsupials like the opossum to both New-and Old-World primates (Sandell, 1986;Franca et al, 1997Franca et al, , 2000. In early reports, however, the presence of type II neurons in rodents ranged from being neglected to altogether dismissed (Mitrovic and Schachner, 1996;Yan and Garey, 1997;Oermann et al, 1999).…”

“…Most of the input to layer IV barrels is carried by axon terminals arriving from the ventral posteromedial thalamic nucleus (VPM) (Koralek et al, 1988;Lu and Lin, 1993), but this nucleus does not seem to contain many NADPH-d reactive cell bodies (Vincent and Kimura, 1992;Kharazia et al, 1997;Simpson et al, 2003). Similarly, in layer IVC of the monkey's visual cortex, there is also a high concentration of dispersed NOS/NADPH-d neuropil but few reactive cellular profiles (Franca et al, 1997). Using electron microscopy reconstructions, Aoki et al (1993) have demonstrated that this NOS-immunoreactive neuropil corresponds predominantly to presynaptic terminals whose origin is still unknown.…”

“…The distribution and histochemical characterization of NADPH-d neurons have been evaluated before in the brain of several mammalian species (Sandell, 1986;Vincent and Kimura, 1992;Valtschanoff et al, 1993;Hashikawa et al, 1994;Kubota and Kawaguchi, 1994;Volchan and Franca, 1994;Yan et al, 1996;Bidmon et al, 1997;Franca et al, 1997Franca et al, , 2000Yan and Garey, 1997;Oermann et al, 1999;Freire et al, 2004). In the mouse barrel field, the distribution of NADPH-d was described before by Mitrovic and Schachner (1996).…”