In vivo phagocytosis by developing myocardial cells: an ultrastructural study.

Phagocytosis of naturally degenerating cells, by healthy myocardial cells of the bulbus cordis of 5--7-day chick embryos, was studied by electron microscopy. Myocardial cells showed cell processes surrounding dead cell fragments. The cell fragments appeared to be internalized later and digested within phagosomes. Ruthenium red was employed to ascertain whether the cell fragments were in fact internalized or located in pockets of the cell membrane. The results are discussed in the light of present knowledge of phagocytosis.