Fig. 6: Scanning electron micrographs (SEM) of normal human PCS-201 cells seeded at low density (5,000 cells per 13 mm glass coverslip, see Supplemental Figure S1).

The cells were grown under standard tissue culture conditions (37 ^oC, 95% O₂, 5% CO₂). Non-TTFields-exposed cells (a) were left under those conditions for the duration of the study. Other cells (b) were exposed to TTFields for 72 h. c Quantification and comparison between TTFields unexposed and exposed cells of the number and size of holes with area ≥ 51.8 nm² (equivalent to a 4-nm radius circle, or 9 pixels² on the 60,000× magnification images) within a 500 nm-radius circular region of interest. The minimum hole size cut-off was based on the 3.3 nm and 5.0 nm Stokes radii of 20 kDa and 50 kDa Dextran-FITCs, respectively. There was no significant difference in the number or size of holes between the TTFields unexposed and exposed normal human PCS-201 cells (Wilcoxon rank-sum analysis). From left to right, magnification levels in a and b are 2,000× (black scale bar 10 µm), 20,000× (black scale bar 1 µm), and 60,000× (black scale bar 200 nm) and final panel column on the extreme right where yellow scale bar represents 200 nm scale. Yellow arrows point to representative holes on cellular membranes. Coverslips from three experiments per condition were used, and at least 5 cells per coverslip were analyzed for hole count and size, in a double-blind manner