Fig. 7. Distribution of ASIP:EGFP and aPKC during neurulation. (A-H) Eight confocal photographs of a z-multilevel apicobasal scan, in steps of 0.75 µm (numbers give the distances in µm), through a few cells of the neural plate of an embryo that had been injected with asip:egfp mRNA. Notice that the fluorescence is punctate and localised to the membrane, but it is not restricted to the apical region. (I) A confocal photograph of an embryo in neural keel/rod stage that had been injected with asip:egfp mRNA. Notice that the fluorescence, although weak, is localised mainly to the apical pole of the cells (arrows), at the region where the two halves of the neural primordium are in apposition. (J-L) Three confocal photographs through three different levels of the neural tube of an embryo injected with asip:egfp mRNA. Numbers give the distances in µm. The fluorescent signal is strong and clearly restricted to the apical pole of the neuroepithelial cells. The width of the neurocoel increases towards ventral levels. (M-O) Anti-aPKC antibody staining. Two different levels of the neural keel (nk), separated by 15 µm, are shown (M,N). Notice that immunoreactivity is restricted to ventral levels of the neural keel (arrow in N). som, somites. (O) An optical section through the neural tube. Note the apical localisation of the epitope.