Tubulin paracrystals in intermitotic nuclei of the foraminifer Allogromia laticollaris Arnold after treatment with vinblastine.

Electron microscopic investigations on the foraminifer Allogromia laticollaris showed that after treatment with 10(-3) M vinblastine tubulin paracrystals can be demonstrated in intermitotic nuclei. As these paracrystals are either membrane coated or lie free in the karyoplasm, and as in the perinuclear cytoplasm, membrane coated paracrystals can be demonstrated as well, it is assumed that the cytoplasmic tubulin which is composing the intranuclear division spindle can transverse the intact nuclear envelope via vesicle transport.