Fig. 5. p75 and ßgal staining reveal separate populations of NC precursor cells in the trunk NT. W^lacZ/+ embryos were stained for p75 using immunohistochemistry and ßgal histochemistry, from stages E9 to E11. Low-power views of these embryos are shown at the left of the panel for each age. Extent of ßgal expression on the dorsal midline of the NT is indicated by dotted lines. High-power dorsal views of cervical, midtrunk and lowertrunk regions of these embryos are shown in the middle of each age panel. For these views, a negative of the bright field image is shown with ßgal staining false-coloured red; each image has been merged with the p75 fluorescence image (green) of the same area. Coronal sections were taken through cervical, midtrunk and lower trunk regions (approximate locations are indicated by bars in low-power views of embryos) and double stained by fluorescence immunohistochemistry for p75 (green) and ßgal (red). These are shown at the right of each age panel. High-power views of the dorsal midline of the NT from these sections are inset into the images where there is any indication of both ßgal and p75 staining in this region. Scale bar: 100 µm.