Microtubule-organizing centers in higher plants.

Compelling evidence has recently been obtained for the idea that the nuclear surface of higher plant cells has a microtubule-nucleating function under cell cycle dependent control. Whatever the final organization of microtubules, they all seem to originate in the nuclear periphery. The spatial distribution of microtubules is a secondary process involving actin and microtubule-associated proteins, and other morphogenetic controls. How microtubules are nucleated and/or reorganized at the spindle poles during mitosis remains unknown.