Fig. 7. Formation of multivesicular endosomes in lvsB mutant cells. (A) Acidic endocytic compartments in DH1-10 and lvsB null cells were visualized with LysoSensor by confocal microscopy of living cells. The white lines delineate individual cells. Acidic endocytic compartments are bigger in lvsB null cells than in wild-type cells. Bar, 5 µm. (B-D) Mutant lvsB cells were left untreated (B) or were treated with U18 for 15 minutes (C) or 2 hours (D). Each sample was then fixed and processed for electron microscopy. Bars, 0.5 µm.