A, E. myf5 -/- MyoD -/-

B, F. myf5 +/- MyoD -/-

C, G. myf5 -/- MyoD +/-

D, H. myf5 +/+ MyoD +/-

Figure 4. Mice Lacking both Myf-5 and MyoD lack skeletal myocytes and myoblasts. Immunohistochemical detection of skeletal muscle with mouse monoclonal antibody reactive with smooth and striated muscle alpha-actin (A and B), and skeletal myoblasts with a mouse monoclonal antibody reactive with desmin (C and D).

In Myf-5 +/-, MyoD +/- mice (A and C), anti-actin antibodies (A) stained skeletal muscle fibers (as well as smooth muscles), whereas anti-desmin antibodies (C) stained both skeletal muscle fibers (thick arrows) and myoblast-like cells (thin arrows). Sections from Myf-5 -/- MyoD -/- mice (B and D) contained no detectable acti0- or desmin-staining skeletal myocytes or desmin-staining skeletal myoblast-like cells.

A, C:

Myf-5 +/-, MyoD +/-

B,D:

Myf-5 -/- MyoD -/-