Fig. 5.

The GRMD diaphragm undergoes a dramatic remodeling that alters passive properties of the muscle. A: schematic cranial view of typical diaphragms from 1-year-old dogs viewed cranially (GRMD, red; normal, blue) showing reduced muscular length in the direction of shortening and expansion of central tendon area in GRMD. B: representative photographs of longitudinal sections of costal diaphragm (location indicated in A) showing reduced muscle length and increased thickness in GRMD. White arrowheads indicate central tendon, orange arrowheads indicate insertion on rib. C: plot of muscular diaphragm length vs. thickness in six dogs with the GRMD mutation and five normal dogs. D: sarcomere length at these muscle lengths do not differ between dogs with the GRMD mutation and normal dogs, indicating that the reduced diaphragm length in GRMD results from removal of sarcomeres in series.