  Nuclear pores have an approximately uniform distribution in the nuclear
envelope of most living cells. Hence, the morphology of the nuclear envelope is
a spherical stomatocyte with a high genus. We have investigated the morphology
of high-genus vesicles under pore-size constraint using dynamically
triangulated membrane simulations. Bending-energy minimization without volume
or other constraints produces a circular-cage stomatocyte, where the pores are
aligned in a circular line on an oblate bud. As the pore radius is reduced, the
circular-pore alignment is more stabilized than a random pore distribution on a
spherical bud. However, we have clarified the conditions for the formation of a
spherical stomatocyte: a small perinuclear volume, osmotic pressure within
nucleoplasm, and repulsion between the pores. When area-difference elasticity
is taken into account, the formation of cylindrical or budded tubules from the
stomatocyte and discoidal stomatocyte is found.
