Immunoelectron microscopy of differentiated transfected HL-60 cells. (A) Labeling of NGAL with rabbit antibody followed by 10 nm gold attached to goat antirabbit IgG. Staining is observed on Golgi stacks (G) and trans-Golgi network (TGN). (B) Labeling of cytochrome b₅₅₈ with MoAb followed by rabbit antimouse IgG and 10 nm gold attached to goat antirabbit IgG. Extensive labeling can be observed on the plasma membrane (large arrows) and on some vesicles underneath the cell surface (small arrows). No label is observed in the granules (g); nucleus (n). Bars, 200 nm.