Fig. 3. BrdU staining in late stage 17 wt and H99 embryos. All embryos were injected at early stage 17. (A) Wt VNC. Sporadic staining can be seen in the abdominal segments. In the thoracic region, BrdU-labeled cells are found only in the very lateral region of each hemisegment. (B,C) VNCs of two H99 embryos, representing the two classes of staining we found in H99 mutants. One shows a similar amount of staining as in wt (B), whereas the other has many more BrdU-positive cells (C). In both cases, there is a concentration of dividing cells in the lateral region of each abdominal hemisegment. The thoracic segments in B and C show reduced staining in the medial regions. Anterior is to the left in all images.