...Gundel Hager; Charles N. David ABSTRACT The nervous system of the fresh water polyp hydra is built up as a nerve net spread over the whole body, with higher densities in the head and the foot. In adult hydra, as a result of continuous growth, new nerve cell differentiation takes place continuously...

... that head activator leads to an increase in cAMP levels at concentrations where effects on nerve cell determination and differentiation are observed (10 −11 to 10 −9 M). Moreover, exposure of intact hydra to a permeable form of cAMP stimulates nerve-cell differentiation and thus mimicks the effect...

... activator stimulates nerve cell differentiation in head tissue ( Holstein et al . 1986 ). Since head activator does not stimulate tentacle-specific NV1 + differentiation in heads, this implies that differentiation of nerve cells other than NV1 + cells must be stimulated. To test this hypothesis, we have...

..., injured with three transverse cuts to stimulate nerve cell differentiation (Holstein et al . 1986) and transferred to hydra medium to continue tentacle regeneration. NV1 + cells were analyzed in whole mounts. Each point represents a single polyp. Lines are derived by linear regression analysis; lines...