Limb regeneration and nerve fiber number inRana sylvatica andXenopus laevis
✍ Scribed by Rzehak, Karol ;Singer, Marcus
- Publisher
- John Wiley and Sons
- Year
- 1966
- Tongue
- English
- Weight
- 569 KB
- Volume
- 162
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Adult Rana sylvatica does not regrow an amputated forelimb whereas Xenopus laevis does. This difference in regenerative behavior has been analyzed in terms of the number of nerve fibers available at the amputation surface because previous studies have shown that nerve fibers must satisfy a quantitative threshold in order that regeneration occur. Our results show that Xenopus has more fibers per unit area than Rana. However, the value for both is far below that of Triturus and, indeed, even lower than that of the mouse. The relative scarcity of fibers in the anuran limb thus brings into question the direct relation previously drawn between nerve number and regenerative capacity in vertebrates. However, anuran nerve fibers are much larger fibers than those of other vertebrates; and, indeed, those of Xenopus surpass in size the fibers of the vertebrates we have investigated. Initial studies show that if the size of fibers is taken into account and the innervation is expressed as amount of neuroplasm available at the amputation surface rather than as the number of fibers, the limb of Xenopus is then as richly innervated as the limb of Triturus whereas that of Ruwa contains much less nervous substance.