Iron-containing cytoplasmic inclusions in mouse bone marrow macrophages.

Elongated, tapered inclusions, present in the cytoplasm of macrophages in mouse bone marrow, were studied by electron microscopy. The bone marrow of adult mice that were injected with the hemolytic agent phenylhydrazine, displayed a statistically significant increase in the number of inclusions compared with bone marrow from control animals. Ultrastructural analysis demonstrated that ferritin, a known product of red cell destruction, was resent in these inclusions. It is suggested that the inclusions are derived from the degradation of phagocytosed red cells.