Figure 7. Enhanced myoblast proliferation in Abl2^−/− mice leads to enhanced myoblast fusion.

Primary cultures from the diaphragm muscle of E18.5 mice were stained with antibodies to myosin heavy chain (MHC) to label differentiated muscle fibers and MyoD to label myoblasts. (A) Representative images of diaphragm muscle cells, which were proliferated for 2 days before a switch to differentiation medium. (B) Under these conditions, Abl2 mutant myoblasts displayed enhanced myotube formation. (C) The number of nuclei per myotube was quantified. Differentiated Abl2 mutant myotubes incorporated more nuclei per myotube. (D) Representative images of Abl2 mutant myoblasts, which were plated at confluent density and directly into differentiation media. (E) Confluent cultures, which did not have an opportunity to proliferate, formed myotubes like wild type myoblasts. Scale bars are 50 µm in A,I, and L. **p<0.01, ****p<0.001.