Epithelial cells in nerve-free hydra produce morphogenetic substances.

It has been shown that hydra, consisting almost exclusively of epithelial cells, have normal morphogenetic properties. This means that they are able to reproduce asexually by budding and to regenerate head or foot with conservation of the original polarity. Such hydra have no interstitial cells and they lack nerves and nematocytes as differentiation produces of the interstitital stem cell. Consequently, they are unable to catch or ingest food and would not survive in ntaure. However, stocks can be maintained in the laboratory, if food is injected into the gastric cavity. The fact that nerve-free hydra would grow and regenerate normally raised some doubts as to the role of the nervous system in the control of differentiation and development in hydra. In particular, the significance of morphogenetic substances, such as the head activator, which is normally produced by nerve cells, seemed to need reassessment. We now show that epithelial cells, seemed toneed reassessment. We now show that epithelial cells in hydra have the potential to produce head activator and other morphogenetic factors, but that this property is repressed in the presence of nerves.