Figure 1. PrP^C expression pattern in the nervous and cardiovascular systems from early developing mouse embryos.

PrP^C (red) and nuclear marker 4’,6-diamidino-2-phenylindole (DAPI, blue) staining of transverse sections from FVB/N mouse embryos at E9 in the developing nervous (a–c) and cardiovascular systems (d,e). Section plans are indicated (f). PrP^C was observed at the level of the apical face of the neuroepithelium in the head region (presumptive telencephalon; a), in the neural tube (NT) in the trunk region (b), and particularly in the floor plate (FP, c). The arrowhead indicates PrP^C-positive differentiating cells in the mantle zone (c). Low-exposure acquisition of two juxtaposed embryo sections from the proximal and caudal trunk regions showed strong PrP^C expression in the omphalomesenteric artery (OA) and in the embryonic heart ventricle (HtV) (d). Higher magnification of the omphalomesenteric artery (OA) (e). The asterisks indicate artefact signals found in FVB/N and in Prnp^−/− mice (supplemental Figure S1), likely due to nonspecific Fc binding to maternal blood, and the arrowheads highlight specific punctuate or patchy PrP^C signals. Scale bar: 10 μm, except in (b,d) 50 μm. DA: dorsal aorta, Hg: hindgut, L: lumen, MDA: midline dorsal aorta, som: somite.