Distribution of NADPH-d positive neurons during postnatal development of the rat somatosensory cortex correlates with gradients of neurogenesis and development.

The expression of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) was studied in the rat somatosensory cortex during postnatal development from day 6 to 120. Distribution of labeled neurons was quantified in dorso-medial and ventro-lateral aspects of the cortex, and correlated with known tridimensional gradients of histogenetic development and maturation of cortical neurons. NADPH positive neurons were non-pyramidal cells that in all developmental periods were more numerous in infragranular than in supragranular layers of the cortex. Additionally, more labeled cells were found in ventro-lateral than dorso-medial infragranular layers and in anterior than posterior aspects of the cerebral cortex. These patterns of distribution correlate well with the gradients of histogenetic development and with the pattern of maturation of cortical neurons.