Fig. 3. Thick cells, but not round cells, express myogenin. Myofibers obtained from gastrocnemius muscle were cultured in pmGM for 7 days. Then, satellite cell-derived colonies were subjected to immunostaining with anti-myogenin antibody. (A,B) A fraction of thick cells (arrowheads) around a myotube (asterisk) expressed myogenin (green in B). Scale bar: 50 µm. (C,D) One of the thick cells (arrowhead), but none of the round cells (within the square), expressed myogenin (D). Scale bar: 20 µm. Nuclei were visualized with DAPI (blue in B and D). (A,C) Phase contrast microscopy images of the same fields as those shown in B and D.