Possible roles of mechanical cell elimination intrinsic to growing tissues from the perspective of tissue growth efficiency and homeostasis
Fig 4
Cell size variance as the common geometrical determinant of the elimination rate.
When the cellular mechanical/growth parameters change, geometrical quantities (specifically, variation in cell size, cell rearrangement frequency, and cell shape anisotropy) and elimination rate change. (A) For example, when the tissue fluidity (that is determined by Λ, Γ, and θT1) increases (or decreases), both the variation in cell size and elimination rate decrease (or increase; top panel). Similarly, for changes in the other parameters, κ (which determines the randomness of division orientation) and μ (growth rate), both cell size variation and the elimination rate change with the same tendency. In this manner, the responses of cell size variation and elimination rate to changes in any parameter are highly and positively correlated. In contrast, the responses in cell rearrangement frequency (B) and cell shape anisotropy (C) to parameter change does not necessarily show the same tendency as the response in cell elimination; for instance, for changes in tissue fluidity and growth rate, the responses of rearrangement frequency and elimination rate are negatively correlated, whereas for changes in division orientation they are positively correlated. Thus, among these three geometrical quantities, only cell size variation had a response consistent with the response in elimination rate, and we can conclude that cell size variance is the common geometrical determinant of the cell elimination rate. Note that cell shape anisotropy was calculated as 1-(length of the shortest axis/length of the longest axis) after approximating each cell by an ellipse. All simulations were performed using a pure population. Symbols: blue crosses (Λ), cyan pluses (Γ), green triangles (θT1), orange diamonds (κ), and red circles (μ).