Immunogold labeling for P-selectin of the cytoplasm from stage I and III wild-type MKs and from light and heavy electron-dense GATA-1^low MKs. (A) Normal stage I MKs are weakly labeled for P-selectin. (B) Normal stage III MKs present many P-selectin gold particles mainly in association with α granules and rarely with the DMS. In contrast, light electron-dense GATA-1^low MKs present few gold particles localized both on the membrane of granulelike structures and on the initial DMS (C), whereas high electron-dense Gata-1^low MKs show numerous gold particles mostly associated with DMS, rarely on vacuoles or dispersed in the cytoplasm (D). Arrows and arrowheads indicate gold particles associated with granules (either α or atypical) and with DMS, respectively. Original magnification × 30 000 for all panels.