FIG 7.

STEM tomography of UL148-dependent ER structures in HCMV-infected cells. Human fibroblasts infected with wild-type HCMV (TB_WT) were fixed by high-pressure freezing and freeze substitution at day 5 postinfection, and tomograms were recorded by STEM. (A) Virtual section through the tomogram of a virus-induced membranous structure; *, ER structures of distended lumenal space. White arrowheads indicate sites at which membranes originating from distended ER cisternae continue into areas of involuted collapsed ER. Scale bar, 1 μm. (B) Same virtual section as in panel A tilted and with a 3D visualization of the membranous network (green) of the entire tomogram.*, the same distended ER cisternae as in panel A. (C) Cross section through image shown in panel B to visualize the membrane profile of the membranous structures. The region delimited by a white box is shown at higher magnification on the right. Finer detail of the enlarged ER cisternae and the connections between them are readily visible; *, the same distended ER cisternae as in panels A and B. Scale bar, 1 μm.