Fig. 7. Myoferlin null muscle regenerates less effectively and shows more fibrofatty infiltrate than does littermate control muscle after cardiotoxin injection. (A) In Mason Trichrome-stained sections of gastrocnemius muscles 9 days after cardiotoxin injection, fatty infiltrates appear white (arrowheads) and fibrotic tissue appears blue (arrows). Scale bar: 100 µm. (B) In sections stained with Oil Red O and Hematoxylin counterstain 13 days after injection, areas of fatty infiltrate appear as round white cells with orange droplets in the myoferlin null tissue. Scale bar: 50 µm. (C) ImageJ was used to quantify the area covered by fatty infiltrates and fibrotic tissue in four images of Trichrome-stained tissue, such as those shown in A, at each of three time points, days 9, 11 and 13 post-injection. Significantly more muscle was replaced with fibrofatty tissue in myoferlin null mice than in wild type.