Fig. 3. (a) Transverse section through a phagosome containing L. pneumophila after a 15 minute infection period. As in (Fig. 2), vesicles of ER, both studded with ribosomes and without, are attached to the phagosome. The region indicated is shown at higher magnification in (b). Both the phagosomal membrane and the ER membranes have the same thickness. (c) Longitudinal section through a phagosome containing L. pneumophila after a two hour infection period at an MOI of 1 applied for 30 minutes. The phagosome is surrounded by attached ER vesicles. The area boxed in (c) is shown at a higher magnification in (d).