Fig. 1. Expression of Mash1 in relation to oligodendrocyte specification in the ventral spinal cord. (A-E) All panels show transverse sections of the rat embryo spinal cord (the dorsal side is top). Molecules stained in red and green are shown on the top, and the stage and axial level of the sections are shown on the left. Horizontal lines indicate the boundaries between the Pax6⁺ (p2), Olig2⁺ (p^*; arrows) and Nkx2.2⁺ (p3) progenitor domains. Insets in Aa-Ad, Ba and Ca-Cd are higher magnification views of the areas indicated by thick arrows. Circles in Aa and Ba indicate Olig2⁺ and Nkx2.2⁺ cells migrating in the MZ. Insets show co-expression (Ac,Ad,Cc,Cd) or segregation (Aa,Ab,Ba,Ca,Cb) of two markers in single cells. Small arrowheads indicate double-positive cells. Db is a higher magnification view of the area boxed in Da. Scale bars: in Ad,Ba,Cd, 100 µm for Aa-Ad,Ba,Ca-Cd; in Bc,Df,Ee,Eg, 50 µm for Bb,Bc,Db-Df,Ea-Eg; in Da, 200 µm.