Figure 3.

Experiments on BC52 cells. (a) Relative cell density increase δn/n = (n₀ − n(1 day))/n₀ of BC52 cells 1 day after an external pressure jump ΔP = 5 kPa as a function of radial distance r normalized by spheroid radius R (circles). Here n₀(r) denotes the cell density at radius r before the pressure jump. Fit of to the experimental data, corresponding to the theory given by equation (4.13) (solid line). Fit parameters and fit quality χ² = 0.8. (b) Radial cell elongation of BC52 cells shown as a function of distance r. Cell elongation is determined as the ratio of cell distances in radial and circumferential direction (see appendix C). The solid line is a linear fit, indicating an increased cell elongation towards the spheroid centre. (c) Angle of the polarity vector of BC52 cells of radial distance r from the centre. The cell polarity angle is based on the position of the centrosome relative to the nucleus of a given cell as shown in the inset. The angle θ = 0 corresponds to the centrosome positioned from the nucleus in the direction towards the spheroid centre. Note that all angles are confined between ±90° which shows strong polarity of the tissue along the radial axis. An isotropic centrosome orientation would correspond to a distribution between −180° and +180°. (Online version in colour.)