Changes in satellite cell population associated with regenerating muscle fibers in rats.

Qualitative and quantitative analysis of satellite cells in regenerating muscles was performed at 4, 7 and 30 days after necrosis induced by mepivacaine injection. At 4 days, the small regenerating fibers were accompanied by a high number of satellite cells showing signs of activation; at 7 days, the number of satellite cells decreased and two morphological types of these cells were observed; at 30 days, satellite cells were similar in both number and characteristics to those of the control group. These results would indicate that satellite cells may vary both in number and morphological and morphometric features, according to the degree of maturity of the regenerating muscle fiber.