Competence of embryonic mammalian heart cells in culture: DNA synthesis, mitosis and differentiation.
The competence for DNA synthesis, mitosis and differentiation of cardiac muscle and non-muscle cells of 14- and 18-day rat embryos was studied in vivo. The heart cells of 14-day embryos were relatively more competent in DNA synthesis and mitosis than those of 18-day embryos. These in vitro findings conformed with those of the in vivo studies. Cardiac muscle and non-muscle cells of the younger age group showed higher labelling indices than those of the other age group during 7 days of culture. The general profile of DNA synthesis was similar in both age group during 7 days of culture. The general profile of DNA synthesis was similar in both age group cells. Maximum labelling indices in muscle and non-muscle cells were observed after 24 h of culture. The number of labelled cells was always higher in non-muscle cells than in muscle cells. As the culture continued, the labelling indices declined in both cell types of the two age groups. On day seven, 10% labelled cardiac muscle cells and 45% labelled non-muscle cells were observed in the 14-day embryonic group, in comparison with 5% cardiac muscle cells and 35% non-muscle cells of the 18-day embryonic group. When the rate of in vitro differentiation of myofibrils, intercellular junctions and some cellular organelles, were compared between cells of two different age group hearts, no significant difference was observed. During the first week of culture, a considerable number of muscle cells contained myofibrils throughout the length and girth of the cells. The intercalated discs differentiate over a period of 3 weeks of culture. As the culture proceeded, adjoining cardiac muscle cells differentiated desmosomes and gap junctions. Cardiac muscle cells retained these structural specializations and did not undergo dedifferentiation in long-term culture. Overgrowth of one cell type by another was the regular occurrence in all heart cell cultures studied.
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D006321:Heart / Q000196:embryology; D007700:Kinetics; D008938:Mitosis; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D051381:Rats
D004247:DNA