Ultrastructure of intramuscular haematomas and electron-probe X-ray analysis of extracellular and intracellular iron deposits

Abstract

Hematomas were produced in rabbits by i.m. injections of autologous blood. Clotting and marked lysis of erythrocytes was noted in these hematomas but there was no evidence of fragmentation of erythrocytes, prior to, during or after ingestion by macrophages as reported in other sites such as spleen, peritoneal cavity or joint cavity. The phagocytosis of intact erythrocytes, lysed erythrocytes and Hb led to the formation of 3 main types of lysosomal bodies, myelinosomes, siderosomes and myelinosiderosomes. Electron-probe X-ray analysis of siderosomes yielded further data supporting the idea that hemosiderin is essentially an inorganic Fe compound; presumably a hydrated ferric oxide. An unusual finding was the occurrence of electron-dense granules in the connective tissue matrix in 2 animals. The granules contained Fe, Ca, K and P. They might represent an attempt at pathological calcification in damaged tissue.