Fig 1. Time course of rat CMV (RCMV) dissemination in the developing brain.

Recombinant RCMV allowing expression of GFP (green) in the infected cells, was injected intraventricularly at E15. Brains were analyzed at various developmental time points using fluorescent binocular microscopy (left panel of each corresponding stage) and confocal microscopy (right panels of each corresponding stage; blue: Hoechst nucleic acid staining). The frequency at which a given area displayed GFP signal (infection index) increased from E17 (n = 18 embryonic brains from two pregnant rats) to E20 (n = 46 embryonic brains from five pregnant rats) and P1 (n = 38 neonatal brains from four pregnant rats). Similarly, the absolute number of GFP⁺, infected cells as counted in a subset of the aforementioned brains (n = 11 brains at E17; n = 11 brains at E20; n = 13 brains at P1) (Table C in S1 File) increased significantly (Kruskall-Wallis test followed by Dunn's post-hoc test) from E17 to P1 in the corresponding brain areas of interest. For each developmental stage and brain area analyzed, each dot represents the number of GFP+ cells per ROI in a given brain. ROI (387x387 μm²): region of interest. OB: olfactory bulb. LV: lateral ventricle. CP: choroid plexi. Th: thalamic area of the third ventricle. Hyp: hypothalamic area of the third ventricle. Areas are shown upon a rostrocaudal axis, from top to bottom. White bars: 1 mm; yellow bar: 200 μm; red bar: 40 μm. ns: non significant; *: p < 0.05; **: p < 0.01; ****: p<0.0001.