Figure 4.

Identification of acidic, recycling vesicles in megakaryocytes. (A) After acridine orange staining, acidic vesicles were observed in the MEG-01 cells (red) in the periphery of the cells. Green fluorescence reports soluble dye within the cytosol. (B) Acidic vesicles were also observed in primary human megakaryocytes (MKs), where additionally to their localization at the periphery of the cells (red), they colocalized with soluble dye in the cytosol of the cell (yellow); bars = 20 μm. (C) Vesicular recycling in primary murine MKs was detected by incorporation of the FM1-43 dye into vesicle membranes during endocytosis, which leads to an increase of green fluorescence within the cells. Following FM1-43 removal, the cells destained within 60 minutes reporting exocytosis of these vesicles.