Figure 6. Nerve cell to epithelial cell ratio along the body column of Hydra.

Transgenic watermelon and inverse watermelon polyps were stained with pan-neuronal antibody (PNab) to identify nerve cells and with DAPI to identify nuclei. Confocal stacks were taken through the body wall at various positions along the body column and scored for ectodermal and endodermal epithelial cells and for nerve cells (see Materials and methods and Figure 1—figure supplement 2). The results are semi-quantitative, since the number of animals scored (shown in brackets) and the number of image stacks varied at each position. A total of 80–400 nerve cells were scored in body column and peduncle samples, 20–30 in hypostome samples, but only 0–2 in the endoderm of tentacle and basal disk due to absence or very rare occurrence of endodermal nerve cells in these body parts.