The nervous system ofNectonema munidae andGordius aquaticus,with implications for the ground pattern of the Nematomorpha |
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Authors: | Andreas Schmidt-Rhaesa |
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Institution: | 1. II. Zoologisches Institut und Museum, Universit?t G?ttingen, Berliner Strasse 28, D-37073, G?ttingen, Germany
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Abstract: | The nervous system of Nectonema munida is shown to be composed of a brain, a ventral nerve cord with an anterior and a posterior enlargement, a dorsal nerve cord
and a plexus-like basiepidermal nervous system. The ultrastructure of these parts is given. Additionally, the ventral nerve
cord of Gordius aquaticus is ultrastructurally described. The results are compared with the literature to work out the ground pattern of the Nematomorpha
according to the nervous system. This contains a circumpharyngeal brain with a main subpharyngeal portion and a weak suprapharyngeal
portion, a ventral and dorsal intraepidermal nerve cord and a peripheral nervous system. The ground pattern of the nervous
system of Nematomorpha is then compared to that of other Nemathelminthes. The form of the brain and the distribution of perikarya
are derived characters of the Nematomorpha. The existence of an unpaired ventral and an unpaired dorsal nerve cord and the
position of these two cords in epidermal cords are synapomorphies of the Nematomorpha and the Nematoda.
Accepted: 7 July 1996 |
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