Figure 1.

All OPs Proliferate in Forebrain Gray and White Matter at P21 and P60

(A–F) EdU was administered to P21 and P60 mice in the drinking water at 0.2 mg/ml, which we previously determined to be nontoxic (Figures S1 and S2). At various labeling times, coronal brain sections were processed to detect EdU (red) and immunolabeled for Pdgfra (green). Images are shown of the corpus callosum (cc) (P21, A; P60, B and C) and medial (primarily motor) cortex (ctx) (P21, D; P60, E and F).

(G) The labeling index was plotted against time of EdU administration (means ±SD, n = 3 mice). The maximum labeling index is the fraction of the OP population that is mitotically active (the growth fraction). In both cc and ctx, all OPs eventually incorporated EdU (GF = 100%). Arrows and arrowheads indicate Pdgfra⁺, EdU⁺ and Pdgfra⁺, EdU-negative cells, respectively. Cell nuclei were stained with Hoechst 33258 (blue). Scale bars represent 25 μm.