Fig. 3.

Myoblasts isolated from nephrin^KO neonatal mice are unable to form mature myotubes. Light micrographs of wild-type (A, B) and knockout (D, E) myocytes after 1 day (A, D) and 4 days (B, E) in differentiation medium. Immunofluorescence staining for desmin of wild-type (C) and knockout (F) cultures demonstrates that the mononuclear cells in the nephrin^KO cultures are myogenic (white arrows). (G, H) Quantification of the fusion indices for control and nephrin^KO myoblasts. The fusion index (FI) is determined by dividing the number of nuclei found within myotubes by the total number of nuclei in a microscopic field (three to four microscopic fields per sample; three independent experiments). (G) Overall FI, counting nuclei in myotubes containing two or more nuclei. (H) FI for myotubes containing five or more nuclei. (I) Percentage of desmin-positive mononuclear cells decreases in wild-type as the FI increases, whereas it remains the same in the nephrin^KO cultures. Asterisk indicates significant differences between wild-type (lilac) and knockout (crimson), P < 0.05.