Diversity of cortical interneurons in primates: the role of the dorsal proliferative niche.
Bottom Line: In human and nonhuman primates, evidence suggests that an additional subset of neocortical GABAergic interneurons is generated in the cortical VZ and a proliferative niche, the outer SVZ.The origin, magnitude, and significance of this species-specific difference are not known.Our findings suggest that these progenitors constitute an evolutionary novelty contributing to the elaboration of higher cognitive functions in primates.
Affiliation: Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA; Institute of Medical and Clinical Biochemistry, School of Medicine, University of Belgrade, Pasterova 2, 11000 Belgrade, Serbia.Show MeSH
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Mentions: To analyze Nkx2.1 gene expression in the cerebral cortex, we studied human and macaque monkey fetal forebrain tissue at the comparable midgestational stages. We found out that Nkx2.1 was expressed in a decreasing gradient, from high in the medial ganglionic eminence (MGE) to low in the cortical wall, on coronal sections cut through the middle of the telencephalon (Figures 1A–1C). We quantified immunolabeled Nkx2.1+ cells (15–22 gestational weeks [GW]; n = 6). In particular, a higher percentage of Nkx2.1+ cells was observed in the cortical SVZ compared to the VZ (Figure 1G). At 15 GW, 4.2% and 9% of cells were Nkx2.1+ in the VZ and SVZ, respectively; at 18–19 GW, 4.9% and 7.8%; and at 22 GW, 2.6% and 6.4% (Figure 1G). These values probably underestimate the real number of cortical Nkx2.1+ cells, since we applied restrictive counting criteria including only cells with the brightest signal.
Affiliation: Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA; Institute of Medical and Clinical Biochemistry, School of Medicine, University of Belgrade, Pasterova 2, 11000 Belgrade, Serbia.