Table 1.

Distribution of internalized BSA-gold over different classes of endosomes

BSA uptake	No. of internal vesicles				Lysosomes
	≤2	3–5	6–9	≥10
5 min	46.3  ± 7.4	41.3  ± 4.9	12.0  ± 2.0	0.4  ± 0.6	0  ± 0
10 min + 15-min chase	14.3  ± 3.5	23.9  ± 3.6	39.5  ± 2.2	10.3  ± 2.3	12.0  ± 2.1

HeLa cells were incubated with BSA conjugated to 5-nm gold for the indicated time points. Numbers represent the percentage of endosomal vacuoles that were positive for BSA-gold (±SD). Note that primary endocytic vesicles are not included in these countings.