FIGURE 3.

Species-dependent NOS1 expression in the developing neocortex. (A) In the mid-fetal human neocortex, NOS1 is specifically expressed in the pyramidal neurons of two neocortical regions underlying language and cognitive functions. In the Broca’s area (red boxes), NOS1 expression (blue), is selectively present in the pyramidal neurons of neocortical layer 5 (L5). NOS1-expressing neurons are assembled into minicolumns (red asterisks) separated by NOS1-negative neurons. In the anterior cingulate cortex (ACC; green boxes), many L2/L3 pyramidal neurons express high levels of NOS1. NOS1 expression in interneurons (open arrowheads) is present throughout neocortical areas and layers with no significant selectivity. (B) In the early-postnatal mouse neocortex, which is developmentally equivalent to the human mid-fetal neocortex, NOS1 is exclusively expressed in interneurons (open arrowheads) and absent from pyramidal neurons.