Fig. 1. Expression of Ascl1 at late embryonic stages. Transverse sections of rat spinal cord at the brachial level at E16.5 (A-D) and E18.5 (E-I). Molecules stained in red and green are shown at the top. Broken lines indicate the boundary between the VZ and MZ or the forming white matter of the spinal cord. Boxes in A and E show the locations of the areas shown in other panels. Insets show double-labeled cells in the dorsomedial white matter (unlabelled boxed areas in A,E) or the ventral white matter (B-D,F). Arrowheads indicate double-labeled cells, whereas arrows in I indicate separate Olig2⁺ and Nkx2-2⁺ cells. FP, floor plate; MZ, mantle zone; VZ, ventricular zone. Scale bars: 200 µm in A,E; in D,H and I, 50 µm for B-D,F-H and I.