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Neurotrophic Contribution to a Proposed Tripartite Control of the Mitotic Cycle in the Regeneration Blastema of the Newt, Notophthalmus (Triturus) viridescens

1978; Oxford University Press; Volume: 18; Issue: 4 Linguagem: Inglês

10.1093/icb/18.4.855

2162-4445

Morton Globus,

Silk-based biomaterials and applications

My work has shown that the neural dependence of the limb regenerate (blastema) for growth, is retained in vitro and it follows the normal in vivo pattern. Implanted dorsal root ganglia promote localized growth in cultured blastemata whereas in the absence of nerves little or no development ensues. Our transfilter studies show that the neurotrophic effect, which appears to be mediated by a factor capable of transmission through thin filters of low porosity, is manifested in a proximo-distal gradient of mitotic activity which diminishes with distance from the nerve source. This mitogenic effect appears to require at least 48 hr for expression, which corresponds to one revolution of the cell cycle. In the absence of nerves, both DNA synthesis and mitotic index in the blastema decline significantly; however, a basal level is maintained which may be nerve independent. In this context and in the light of pertinent recent literature, we present a model in which nerves, the apical epidermis and insulin (tripartite control) all play essential roles in the mitotic cycle.