The development of cnidarian stinging cells: maturation and migration of stenoteles of Hydra vulgaris.

The late stages of stenotele development and the migration and installation of freshly matured stenoteles in Hydra have been studied by kinetic and immunofluorescence investigations with rhodamine-labelled polyps. It was found that the high concentration of osmotic pressure-generating poly(γ-glutamic acid)s is synthesised exclusively within the lumen of the immature nematocyst. Assembly of the polymers, which is completed after approximately 0.5 days, is accompanied by a swelling of the capsule and ends when the cyst is mature. Active migration of the stenoteles to the tentacles begins only about 1.0 day later, and the time required for installation of a stenotele on the outer surface of the tissue amounts to about another 1.5 days. Furthermore, the results obtained suggest that the disintegration of the clusters of growing stenoteles, which begins 0.5 to 1.0 days before maturation, is a passive process; the ability of a nematocyte to migrate actively to the tentacles is acquired after maturation and might be controlled directly by regulating factors contained in the tissue.