Fig. 4. Chlamydiae are capable of rapid migration in host cells. Chlamydial migration was inhibited after entry by treating infected cells with nocodazole for 4 hours. This allowed time for chlamydial protein synthesis and modification of the inclusion membrane. Nocodazole was replaced with complete media and cultures were further incubated for 15 minutes or 1 hour. Simultaneous visualization of cells stained with antibodies to tubulin and L2 EBs revealed that after 15 minutes of nocodazole washout a few microtubules had reformed and there was an obvious MTOC (arrowheads). The merged image shows many of the nascent inclusions are aggregated at this site. After one hour the microtubule network is nearly restored. The tubulin staining shows two MTOC in this cell (arrowheads). In the merged image the majority of the chlamydial staining localizes to one or the other MTOC. Bar, 10 µM.