Figure 4
From: Spatiotemporal variation of endogenous cell-generated stresses within 3D multicellular spheroids
Measurements of spatiotemporal variations in endogenous cellular stresses and droplet movement in 3D tooth mesenchymal cell aggregates. (A) Maximum intensity projection of a single droplet (red; surface label) within a 60 hours cell aggregate (green). Scale bar, 100 μm. (B,C) Definition of X s as the closest distance of the droplet center (white circle) from the aggregate’s surface (dashed line), obtained from the contour plot of distance from the aggregate’s surface (C). Scale bar, 20 μm. (D) Spatial variation in anisotropic stresses within tooth mesenchymal cell aggregates at 24 (black; N = 30), 48 (blue; N = 28) and 60 (red; N = 24) hours (N = number of aggregates). For each time, data points were binned into four groups. Data points and error bars in each bin correspond to mean ± s.e.m of anisotropic stress and X s . For each bin, moving from the leftmost to the rightmost point: N = 4, 8, 13 and 5 (24 hours), N = 4, 7, 10 and 9 (48 hours) and N = 4, 7, 8 and 5 (60 hours). The average aggregate radii for 24, 48, and 60 hours are 98.2 ± 5.7, 103.7 ± 5.8 and 110.2 ± 6.5 μm, respectively (mean ± s.d.). (E,F) Temporal evolution of droplet position (E) and average aggregate radius, R, (F) for three different aggregates, each containing a single droplet, over 12 hours (from 48–60 hours). In each case, the droplet moves towards the center of the aggregate while the aggregate grows. (G) Average droplet velocity relative to the aggregate’s surface (−dX s /dt), average aggregate radial growth velocity (dR/dt) and also the absolute droplet velocity (−dX s /dt + dR/dt). Values reported represent average ± standard error of the mean.
