Fig. 2. Loss of engrailed expression in the `bottle cells'. (A-C) Lateral view (focused on the ventral midline) of wild-type embryos stained with anti-Engrailed (red) and anti-HRP (green). (A,B) At stages 12 and 13, Engrailed and HRP immunoreactivity co-localises (although this is not clear at all focal planes). (C) By contrast, at stage 14 the so-called bottle cell downregulates Engrailed expression although it remains labelled with HRP (white arrow). No attempt was made to identify the staining detected inside the embryo, which could be in the mesoderm or the nervous system.