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Schlagwörter:
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Zusammenfassung:
Diffusion gradients of morphogens have been inferred as a basis for the control of morphogenesis in hydra1,2, and morphogenetic substances have been found which, on the basis of their molecular weight (MW), should be able to pass gap junctions3–7. There have been several reports of the presence of gap junctions between epithelial cells of hydra8–13. However, until now, there has been no report published on whether these junctions enable the epithelial cells to exchange molecules of small molecular weight, as has been described in other organisms14–20. Therefore we decided to investigate the communicative properties of the junctional membranes by electrophysiological methods and by intracellular-dye iontophoresis. We report here that no electrotonic coupling is detectable between epithelial cells of Hydra attenuata in: (1) intact animals, (2) head-regenerating animals, (3) cell re-aggregates, and (4) hydra that have become nerve-free. Furthermore we show that epithelial cells are unable to exchange low-molecular weight fluorescent dyes.
