Figure 5

Extensive differentiation and fusion of primary equine and bovine muscle immunolabeled for the muscle markers desmin and α-sarcomeric actin. Equine muscle cells isolated from the red (oxidative) biceps femoris fused as readily as duck muscle cells (a-d). At day 4 of culture, equine cells appeared to express the highest level of desmin in relation to all the species examined (a, b). With over 95% of cells positive for desmin, the equine muscle culture ostensibly contained very few non-muscle cells (b, arrows). α-Sarcomeric actin immunolabeling (brown staining) was detected in equine myotubes but not in mononucleated cells (c, d). Bovine myogenic cells from psoas major (oxidative muscle type) also showed extensive cell fusion after 3 days of culture (e-h). Desmin expression was present in all myotubes (e, f) but also in some myoblasts (e arrows, f arrows). α-Sarcomeric actin was detected in bovine myotubes only (g, h). Haematoxylin nuclear counterstain was used.