Fig. 2. BMP4 inhibits the development of oligodendrocytes in cultures of ventral neural tube explants, with no obvious stimulation of astrocyte differentiation. E1.5 medial neural plate explants (MNPs; A,B,E,F), initially grown for 3 days (final age 4.5 days), and ventral neural tube explants (VNT; C,D) dissected at E4-4.5 were left untreated (A,C,E) or treated (B,D,F) with 0.6 nM BMP4. After 4 and 7 days of treatment of MNP and VNT explants, respectively, cultures were stained with O4 antibody (A-D) or GFAp antibody (E,F). Note the drastic reduction in the number of O4+ cells (quantified in Table 1) in BMP treated explants (B,D). By contrast, the density of GFAp-positive cells is not increased upon BMP treatment (E,F); see text for quantification.