ORGANIZATION OF THE MITOTIC SPINDLE IN HIGHER-PLANT CELLS

In higher plant cells, microtubules form the interphase arrays (cortic al or radial), the preprophase band, the mitotic spindle, and the phra gmoplast. The origin and mechanism of the formation of these structure s have been highly debatable until now. The reason for this is that pl ant cells do not contain discrete, well-defined centers of microtubule organization similar to the centrosome. This review considers the org anization of the mitotic spindle in higher plant cells, using the endo sperm of the South African blood lily (Haemanthus katharinae Baker.) a s an experimental model, and the behavior of microtubules in spontaneo usly arisen cytoplasts (a nucleate cell fragments), which can be chara cterized as self-organization. Self-organization is the result of the dynamic interaction between microtubules and motor proteins. It is sug gested that this process provides for the assembly of bipolar fibers, including the spindle, which is independent of the presence of microtu bule-organizing centers.