Fig. 12

Mechanical forces are critical for filament morphology changes. a Schematic of filament during invasive growth. Lighter green indicates a portion of the filament within PDMS; D1, compartment or proximal cell diameter; and D2, tip diameter. b The diameter of the cell compartment increases as it becomes further away from the filament tip during invasive growth. Cell compartment diameter (measured at 5 equidistant positions between 2 septa), initially on average 5 μm from tip, was determined from 3 independent experiments acquired as in Fig. 11b (n = 5–10 cells) grown on or within 35:1 PDMS (~ 150 kPa). Distance from the compartment center to the tip was determined at each time. The diameter was normalized to the diameter of the last time point for each cell and further normalized by the mean difference between the final compartment diameters of invasive cells compared to surface cells. Each color represents a cell. c Filament tip diameter does not vary as a function of filament length for surface and invasive growth. Tip diameter (2 μm back from the apex) measured for one cell growing on PDMS surface and one cell growing within PDMS, over a 2-h time course. d Tip diameter increase does not underlie proximal cell diameter increase during invasive growth. Tip and proximal cell diameters were measured from the same cells as in a. Proximal cell diameter was measured at the center of the cell proximal to the apical cell over the 2nd hour of the time course (filaments > 30 μm long). Bars indicate SD, with ****p < 0.0001 between the tip and the proximal cell during invasive growth and ***p = 0.0003 between the invasive and surface tips