Researchers have observed stem cells in the muscles of live zebrafish dividing to produce both more stem cells and cells that repair injury.
This 'asymmetric division' of stem cells has been observed in culture. To find evidence in living organisms, Peter Currie and his colleagues at Monash University in Clayton, Australia, engineered zebrafish larvae to produce fluorescent proteins in their muscle cells, and monitored them over time using microscopes. They found that after an injury, stem cells infiltrated the wound and divided to produce two distinct cell types: one went on to form new muscle tissue, while the other had high levels of cmet, a marker specific to stem cells in muscle and other tissues.
This system of cell renewal could be a feature of vertebrates in general, the team says.
Science http://dx.doi.org/10.1126/science.aad9969 (2016)