Effects of ascorbate on myogenesis in micromass culture

Micromass cultures from stage 23 and 24 chick wing mesenchyme were grown in serum-containing medium with or without additional ascorbic acid. It was found that ascorbic acid administered as a single pulse or present continuously throughout culture, in concentrations as low as 25 micrograms/ml, was sufficient to abolish 80% of myogenesis as assessed by immunolocalization using muscle-specific antibodies. This effect was not significantly altered when cultures were maintained in a serum-free medium that promotes myogenesis. In contrast to the above findings, spectrophotometric analysis of accumulated sulphated glycosaminoglycans, an indicator of chondrogenesis, was elevated by ascorbate treatment. Furthermore, a similar level of glycosaminoglycan stimulation was found in ascorbate treated stage 23 distal-tip limb cultures that were essentially free of myogenic cells. We conclude, therefore, that the presence of myoblasts in whole-limb cultures has no appreciable inhibitory effects on chondrogenesis.