Figure 1.
A mechanical model for nuclear morphology. (A) Nuclear envelope (blue) is shaped by forces from the nucleoplasm and cytoplasm. These forces are mainly due to cortical actin (red), microtubules (green), chromatin (pink), and an osmotic pressure difference between the nucleoplasm and cytoplasm. (B) In the absence of forces, the nucleus is assumed to be a spherical membrane of radius R and thickness H. (C) The net contribution from osmotic pressure, microtubules, and chromatin is assumed to be an inflating pressure P. The force due to cortical actin, F, is assumed to be originating from a flat plate that is pushing down on the nucleus. The equations of equilibrium of the membrane in the normal and tangential directions are shown. T1 and T2 are the forces per unit length in the principal directions, and C1 and C2 are the principal curvatures. The solutions to the equations depend only on two nondimensional parameters, η1 and η2. To see this figure in color, go online.