Fig. 4. Inverse correlation between Hes1 and Mash1 expression levels in the spinal cord. (A-D) Double immunostaining for Hes1 and Mash1 at E10.5. Boxed region in C is enlarged in D. (E-G) A higher magnification of a boxed region in D. Cells expressing Hes1 at a high level (green) do not express Mash1 whereas a cell expressing Mash1 at a high level (red) does not express Hes1. Cells expressing Hes1 at an intermediate level express Mash1 at an intermediate level. (H) The results in E-G are shown schematically. Green and red cells are Hes1 positive only and Mash1 positive only, respectively, whereas striped cells are Hes1;Mash1 double-positive. Scale bars: 100 µm (C), 50 µm (D).