Fig. 1. (A) Negative stained EM of PCTVs generated from intestinal ER. PCTVs (fractions 1-7 from Fig. 2A) were formed from intestinal ER and examined by EM. All the vesicles appear intact and range in size from 142-347 nm (12,000x). The bar represents 500 nm. (B) Thin section transmission microscopy of PCTVs and protein vesicles (inset). PCTVs and protein vesicles were stained and processed for thin section EM (5000x). PCTVs are 350-500 nm in size and contain osmiophilic lipid. Bar, 500 nm. (Inset) Protein vesicles (fractions 9-12 from Fig. 2C, prepared for EM appeared as 70-117 nm in diameter and lacked lipid. Bar, 100 nm. For details, see Materials and Methods.