Some glutamatergic periglomerular interneurons are of extrabulbar origin at perinatal ages. (A,B) Distribution of Neurog2 protein throughout the SVZ, RMS and OB. (A) The P0 forebrain SVZ divided into five areas: olfactory bulb SVZ (obSVZ); RMS, also containing the more rostral portion of the lateral ventricle; lateral SVZ (lSVZ); dorsal SVZ (dSVZ, also named subcallosal SVZ); and hippocampal SVZ (hpSVZ). (B) The percentage of Neurog2-positive cells found in each area in a 40-μm thick sagital section from three independent animals. Error bars indicate S.E.M. (C) Co-staining of Neurog2 protein with Pax6, Tbr2 and Tbr1 showing a similar sequential expression of the four markers as observed at earlier developmental stages in the OB. Neurog2 protein shows a strong co-localization with Pax6 and Tbr2, but is down-regulated before Tbr1 expression. (D-G) GFP(+) cells arising from the dorsal SVZ give rise to some Tbr2-expressing juxtaglomerular OB neurons. Electroporation at birth of a GFP plasmid in the lateral (D) and dorsal (E) walls of the lateral ventricles at birth. (F,G) Only the dorsal electroporated animals show some Tbr2-positive juxtaglomerular neurons 12 days later, illustrating the extrabulbar origin of some OB glutamatergic juxtaglomerular neurons. Scale bars: 100 μm in (A, inserts); 20 μm in (C).