Journal ArticleDOI
Excitability of nerve-free hydra
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TLDR
The behaviour of Hydra attenuata in effectively nerve-free animals is investigated and it is shown that such behaviour as remains, is controlled by non-neuronal cells.Abstract:
THE simplest nervous systems known are those of Coelenterate polyps, of which hydra is one. Nerve cells of the common freshwater hydra occur in a diffuse, two-dimensional nerve net dispersed among the epithelial cells of the outer, ectodermal layer1–4. There are also a few nerve cells in the inner, endodermal layer but these are scattered and do not seem to form a continuous net5. Nowhere in a hydra are there nerve cell concentrations or clusters of sufficient complexity to warrant being called ganglia. There have been many behavioural and electrophysiological investigations of hydra6–9, but the function of the nervous system in the control of behaviour is still unclear. In other coelenterates epithelial cells have been shown to be capable of propagating behavioural signals10,11. Several conducting systems coupled with spontaneously active pacemakers have been identified in hydra, but it is not known which of these conducting systems, if any, are neuronal and which result from activity in non-neuronal, epithelial cells. We have investigated the behaviour of Hydra attenuata in effectively nerve-free animals and show that such behaviour as remains, is controlled by non-neuronal cells.read more
Citations
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Journal ArticleDOI
Development of Hydra lacking nerve and interstitial cells
TL;DR: It is concluded that hydra consisting only of epithelial cells are capable of essentially normal development and only in some quantitative aspects do I cell-free hydra develop abnormally.
Journal ArticleDOI
Non-overlapping Neural Networks in Hydra vulgaris
Christophe Dupre,Rafael Yuste +1 more
TL;DR: This work uses calcium imaging of genetically engineered animals to measure the activity of essentially all of its neurons, and surprisingly finds a series of functional networks that are anatomically non-overlapping and are associated with specific behaviors.
Journal ArticleDOI
A second sensory--motor--interneuron with neurosecretory granules in Hydra.
TL;DR: Using serial-sectioning techniques for conventional transmission and high-voltage electron microscopy, it is demonstrated for the first time that the granule-containing sensory cells have synaptic contacts with other neurons, nematocytes, and epitheliomuscular cells.
Journal ArticleDOI
A genomic view of 500 million years of cnidarian evolution
TL;DR: The next challenge is to understand how this genomic history has led to the striking diversity seen in this group of animals, as discussed here.
References
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Journal ArticleDOI
A quantitative method for maceration of hydra tissue
TL;DR: In this article, a method for the maceration (dissociation) of hydra tissue into single cells was described, and the cells had characteristic morphology such that all basic types (e.g., epithelial, gland, mucous, interstitial, nematoblast and nerve) can be distinguished.
Journal ArticleDOI
Mass culture of hydra: an improved method and its application to other aquatic invertebrates
TL;DR: Virtually unlimited numbers of hydra can be grown under precise conditions in the laboratory with relative ease and the advantages of laboratory cultivation of aquatic invertebrates are discussed.
Journal ArticleDOI
Elimination by Hydra interstitial and nerve cells by means of colchicine.
TL;DR: Hydra treated with colchicine or Colcemid become depleted of 95-99% of their interstitial cells and derivatives of this stem cell: nematoblasts, nematocytes and nerve cells; the resultant hydra, though devoid of nematocysts, can be artificially fed.
Journal ArticleDOI
Co-Ordinating Systems and Behaviour In Hydra : I. Pacemaker System of the Periodic Contractions
L. M. Passano,C. B. McCULLOUGH +1 more
TL;DR: Contraction-burst patterns have been studied quantitatively in two species, showing interspecific differences between both regular contraction bursts and those associated with locomotion, and certain extrinsic and intrinsic variables affect contraction-burst frequency.
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