Folding of the PM-cortex layer in TEM. (A and B) TEM of a cell fixed during oscillations. Yellow rectangle (A) shows the position where the magnified image (B) was taken. (C and D) Visual similarities between TEM and DIC (C) and confocal fluorescent images (D, Lifeact-GFP) of oscillating CHO cells. Red arrows point to dense cortical regions in the TEM image (A and B) and presumed membrane folds in the DIC image (C) that are correlated with the dense, thick F-actin cortex in the confocal fluorescent image (D). Blue arrows point to smooth areas, lacking folds on cell periphery in TEM and DIC images (A and C), respectively, and a thinner cortical F-actin layer in the confocal fluorescent image (D). (E) Schematic view of PM-cortex folding and unfolding (middle) and corresponding confocal fluorescent images of the PM (red) and F-actin (green). The yellow rectangle in the top panel (t = 0) shows the position of the rest of the images (Video 5).