The relationship between ferritin and haemosiderin

Under conditions of iron overload haemosiderin may replace ferritin as a major iron store. Much of this haemosiderin is contained within secondary lysosomes, known as sidersomes, where it is thought to have arisen by breakdown of ferritin. The authors report on 57Fe Moessbauer studies of ferritin and haemosiderin prepared from iron loaded rat livers and measured over a wide temperature range. The results indicate significantly different superparamagnetic blocking temperatures consistent with the model whereby haemosiderin is derived from ferritin by lysosomal degradation. (Auth.)