Reversibility of the mononucleate-to-multinucleate myogenic transition during amphibian limb regeneration.
Muscle differentiation involves the fusion of mononucleate myoblasts to form multinucleate syncytial myotubes. In order to assess reversibility of the mononucleate-to-multinucleate transition in urodele limb regeneration, myotube formation was induced in cultured newt limb blastemal cells. Myotubes were purified, replated at low density and injected with a cytoplasmic lineage tracer. In some cases nuclei of myotubes were labelled by incorporation of tritiated thymidine. Labelled myotubes were stable in culture for 6-8 weeks and no transfer to mononucleate cells was observed. The myotubes were implanted under the wound epidermis of a hindlimb blastema. Labelled mononucleate cells were observed 1 week after implantation and such cells could derive both the cytoplasmic lineage tracer and the nuclear marker. The number of such cells increased by 2-3 weeks after implantation. These results provide strong support for the reversibility of muscle differentiation during urodele limb regeneration, and raise questions about the mechanism of such a reversal.
Ludwig Institute for Cancer Research, London, UK.
J P
JP
Brockes
D C
DC
Lo
D000818:Animals; D002452:Cell Count; D002454:Cell Differentiation; D002455:Cell Division; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D005121:Extremities; D009132:Muscles / Q000166:cytology / Q000502:physiology* / Q000637:transplantation; D012038:Regeneration / Q000502:physiology*; D012455:Salamandridae / Q000502:physiology*