Direct membrane contacts sites between erythroid mitochondria and lysosomes. (A) Imaging flow cytometry showing bright field (BF), glycophorin A (GPA), mitochondria (Mito), nuclei (DAPI), and Lamp1 (L1) in erythroid progenitors. (B) Fluorescence microscopy for Lamp1 and MitoTracker Deep Red FM in erythroid and granulocytic progenitors (confocal image with 63× oil objective, subjected to additional magnification). (C) Transmission electron microscopy of erythroid progenitors. (D) Transmission electron microscopy of erythroid progenitors. Arrow denotes contorted mitochondrion in direct contact with 2 MVB/lysosomes. (E) Quantification of membrane contacts observed by transmission electron microscopy of erythroid progenitors as in (D) (number of cells counted = 48 per group; ***P < .001). (F) Transmission electron microscopy of erythroid progenitors subjected to 10 nm gold-conjugated transferrin uptake, with micrograph depicting mitochondria in direct contact with transferrin-laden MVB/lysosome. (G) Total heme content in erythroid progenitors ± overnight treatment with 2 nM Bafilomycin (BAF; n = 4 per group; **P < .01). (H) Transmission electron microscopy of erythroid and granulocytic progenitors highlighting proximity of mitochondria to MVB/lysosome. (I) Quantification of mitochondria-MVB/lysosome membrane contacts observed by transmission electron microscopy of erythroid and granulocytic progenitors as in (H) (number of cells counted = 48-53 per group; *P < .05).