Myogenicity in vitro and in vivo of mouse muscle cells separated on discontinuous Percoll gradients.

Mouse muscle cells, obtained by enzymatically disaggregating newborn mouse muscle, were separated on a discontinuous Percoll gradient. The myogenicity in vitro of the resultant cell fractions was examined by counting the percentage of nuclei in myotubes. Myogenicity in vivo was assessed by implanting a cell suspension of one of the allotypes of glucose-6-phosphate isomerase (GPI) into a regenerating skeletal muscle graft of a second GPI allotype: the finding of hybrid GPI indicated that the implanted cells were myogenic. Separation of mouse muscle cells on a discontinuous Percoll gradient gave rise to two myogenic fractions, one of which was more myogenic in vitro than were the unseparated cells and one of which was less myogenic. Both of these fractions were myogenic in vivo. A cell fraction was also produced which was non-myogenic in vitro as well as in vivo. In vitro and in vivo measurements of myogenicity were therefore in broad agreement.