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Cell migration through narrow spaces is essential in wound healing and metastatic spread of cancer. Cells must deform the large nucleus to fit through constricting channels. To understand the role of the nuclear lamina in limiting cell migration through constrictions, we imaged it in cells migrating through periodic constricting channels in a microdevice. The lamina underwent cycles of wrinkling and smoothing as the nucleus changed from an irregular, rounded shape in the wide channel regions between constrictions to a smooth, hourglass shape as the nucleus passed through the center of a constriction. The laminar surface area of nuclei within constrictions was measured to be at or above the computationally predicted threshold area for the nuclear volume. The channels excluded control nuclei that had insufficient excess surface area, but not nuclei lacking lamin A/C. Thus, the excess surface area of the nuclear lamina enables cell migration through constricting channels. 

The resistance of the liquid drop-like nucleus to deformation is dependent on whether the nuclear lamina is smooth or wrinkled. When it is smooth and taut, the nuclear shape can be calculated from geometric constraints on volume and surface area.