Abstract
Techniques for culturing heart cells in vitro have until recent years been limited to inflexible experiments utilizing plasma clots, serum, and tissue extracts on heart tissue obtained from embryonic sources. Carrel (1912; 1914) and other early investigators, notably Ebeling (1913; 1922), reported observations from a strain of chick heart fibroblasts maintained for 34 years before it was terminated. Although these pioneer workers were primarily concerned with the long-term maintenance of a variety of primary cultures, and for a time overlooked the heart's amazing capacity to beat, Carrel (1912) did make one interesting observation. Initial plasma clot cultures contained cells which displayed beating for the first three days. If the culture was allowed to grow further, beating stopped. Subsequent removal of the peripheral cells, leaving a central cell mass, resulted in resumption of spontaneous contractions. Apparently, intercellular relationships within the entire population have some effect on the heart's intrinsic capacity to beat, a consideration which was recently reemphasized by Eagle (1965) for a variety of other cell types.