1999 Fiscal Year Final Research Report Summary
Movements and their control mechanism in the alimentary canal of amphibian tadpoles
| Project/Area Number |
09640808
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | Shimane University |
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Principal Investigator |
NAITOH Tomio Shimane University, Faculty of Life and Environmental Science, Professor, 生物資源科学部, 教授 (40069042)
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| Project Period (FY) |
1997 – 1999
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| Keywords | intestine / colon / innervation / vagus nerve / splanchnic nerve / VIP / circular muscle layer / longitudinal muscle layer |
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| Research Abstract |
Movements and innervation of the alimentary canal of amphibians tadpoles were studied from the standpoint of comparative physiology.
Direct observation of the gut through the transparent abdominal wall in some species such as Rana ornativentris indicated that there occurred descending contraction waves in the midgut and haustral churning plus rhythmic longitudinal shortening in the colon. Vital staining with methyline blue showed that the vagus nerve, splanchnic nerve and a branch of the ischiococcygeal plexus innervated the alimentary canal, which was basically the same as that of frogs. There exists an intrinsic nerve plexus including VIP-and NO nerve fibers in the alimentary canal. VIP and serotonin administered to the isolated midgut of Rana catesbeiana inhibited its rhythmic contractions. Acetylcholine augmented them. These imply that the gastrointestinal movements of the tadpole gut are under the control of autonomic nervous system. Immunohistochemical staining of smooth muscle cells showed that the musculature in the gut wall consisted of two layers : inner circular and outer longitudinal layers in any part of the alimentary canal. Arrangement of the muscle cells in the longitudinal muscle layer of the midgut is not tight. Muscle cells of both circular and longitudinal layers in the colon are arranged in the manner that may cause haustral churning.
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