Fig. 1. BMP4 inhibits the development of oligodendrocytes and motor neurones in medial neural plate cultures. Medial neural plate explants were dissected from E1.5 embryos (stage 10), and grown in vitro in the absence (A,D,G) or in the presence (B,E,H) of 0.6 nM BMP4. Oligodendrocytes were stained after 7 days in vitro (div) by O4 antibody (A,B) and after 11 div by OL-1 antibody (D,E), which labels more mature oligodendrocytes. Motoneurones and floor-plate cells were stained after 2 div (G,H) with anti-Islet 1 antibody (red) and by anti-HNF3ß antibody (green). Note that BMP treatment strongly inhibited the development of oligodendrocytes and motoneurones but had no effect on the development of floor plate cells. (C,F,I) The mean number of cells of the oligodendrocyte lineage (C-F) and of motoneurones (I) was determined in control and treated conditions. Scale bars represent the mean±s.e.m. of three to five independent experiments.