Fig. 7. Reduced proliferation and early progenitor cell cycle exit in cD2^-/- MGE. All sections, 4 µm. (A) Fewer nuclei label with the M-phase marker PH3 in the VZ and SVZ of the cD2^-/- MGE than in WT. (B-D) Fewer nuclei are labeled by a 1-hour BrdU pulse in cD2^-/- (C) than WT (D) MGE. The proportion of total (DAPI) nuclei labeled by anti-BrdU is significantly reduced in the SVZ. (E-G) Dual-immunolabeling with BrdU and Ki67 (to label S-phase through M-phase cells) shows the total numbers of nuclei labeled by a 24-hour BrdU pulse is slightly reduced in cD2^-/- MGE, but numbers of BrdU+ nuclei not co-labeled with Ki67+ are increased in the MGE of cD2 nulls (F), as compared with WT (E). Quantification of dual (P fraction) and single (Q fraction; BrdU alone) labeled cells indicates a decrease in the proliferating, P fraction and a corresponding increase in the quiescent, Q fraction in cD2^-/- MGE (G), suggesting progenitors are prematurely depleted in cD2^-/- mice. ^*, P<0.05; ^**, P<0.01; ^***, P<0.003.