Semiautomated evaluation of morphometric data on myoblasts and myotubes and the calculation of the relative DNA content with the television texture analysis system (TAS).

In cell cultures of skeletal muscles from 11 day-old chick embryos, myoblasts begin to fuse to myotubes on the second day of culture. Morphological data such as area of projection of the nucleus, length of myotubes and number of nuclei per myotube, as well as histochemical data such as relative DNA content and degree of chromatin condensation were evaluated. The myotubes examined, up to 216 h in culture, had an average of 7 nuclei. These nuclei, which had ceased DNA synthesis prior to cell fusion had less dense chromatin than the nuclei of myoblasts. The data which represent DNA condensation support the concept that transcriptional activity is enhanced during de novo synthesis of muscle protein.