Fig. 3: Dynamics of live cells visualized using 3D-MP-SIM.

a, Average intensity projection of late endosomes in live COS-7 cells imaged using 3D-SIM and 3D-MP-SIM. Scale bar, 5 µm. b,c, Magnified x–y and y–z cross-sections at the indicated time points (for the boxed regions in a), demonstrating the late endosomes at similar movement speeds (approximately 0.5 μm s⁻¹) and highlighting the reduced motion artefacts for 3D-MP-SIM (c) with respect to 3D-SIM (b). Scale bars, 1 µm. d, MIP of the outer mitochondrial membrane in live COS-7 cells imaged using 3D-MP-SIM (left), along with the magnified x–y views of the region highlighted by the yellow dashed box at the indicated time points (right). Scale bars, 5 µm. e, Magnified x–y and y–z cross-sections along the dashed line marked of the x–y view at the indicated time points (for the region highlighted by the white dashed box in d); the white arrowheads point to a fission process completed at 11.78 s, and the yellow arrowheads point to a fusion process occurring at 14.26 s. Scale bars, 1 µm. f, Magnified x–y and y–z cross-sections along the line indicated by the two arrows in the x–y view, for the region highlighted by the white dashed box in d, at the indicated time points, showing the fission process in mitochondrial nanotunnels, with invagination occurring at 18.91 s and fission completing at 19.22 s. White arrowheads indicate the tip and fission of mitochondrial nanotunnel. Scale bars, 1 µm. g, MIP of the ER in live COS-7 cells imaged using 3D-MP-SIM. Scale bar, 5 µm. h, Magnified x–y and x–z cross-sections along the line indicated by the two arrows in the x–y view at the indicated time points (for the region highlighted by the dashed box in g). The white arrowheads in the x–z cross-sections highlight the ER dynamics: extension across a tubular ER at 3.82 s, fusion with another ER tubule at 4.82 s, further extension from the lower part of the fusion point at 4.91 s and contraction at 5.82 s. Scale bars, 1 µm. i, Magnified x–y and y–z cross-sections along the extension ER indicated by the dashed line in the x–y view at the indicated time points (for the region highlighted by the dashed box in g), showing the rapid merging of the two sheet-like ER structures into one. The white arrowheads highlight the corresponding events in the y–z views. Scale bars, 1 µm. All cross-section slices are 30 nm thick.