Cytochemical Demonstration of Transferrin in the Mitochondria of Immature Human Erythroid Cells

Abstract

The direct immunoperoxidase technique was employed to show the localization of transferrin in immature human erythroid cells. The present method is interesting in that use, was made of a small marker (HRP-Fab'' complex) and in that the endogenous peroxidase was blocked under a controlled condition; this ensured good structural preservation allowing EM examination. Cytoplasmic transferrin was found not only in the micropinocytotic vesicles but also within the mitochondrial membrane. Similar findings were made in all the immature erythroid cells examined, each of which was in a different erythropoietic condition. The present study provides morphological evidence for the endocytotic Fe transport to the mitochondria.