Fig. 9. Round cells divide slowly and generate new round cells. (A) The behavior of round cells on day 6, 7 or 8 of myofiber cultures (black symbols), and thick cells at early passages (white symbols), was recorded by time-lapse microscopy. Cell numbers in the same fields were counted every 6 hours. Three independent cultures of round cells or thick cells were analyzed. (B) A round cell on day 6 of the fiber culture (arrowhead) generated two daughter cells (asterisks) displaying a rounded shape. The images were taken at the indicated time points. Scale bar: 10 µm.