Abstract
Carboxyfluorescein-labeled brain tubulin has been microinjected into stamen hair cells of Tradescantia, and its distribution during mitosis and cytokinesis was examined using confocal laser scanning fluorescence microscopy. The results show that brain tubulin incorporates into plant microtubules and is utilized throughout mitosis and cytokinesis. Microtubule structures that incorporate brain tubulin include the preprophase band, the perinuclear sheath at late prophase, the kinetochore fibers during prometaphase, metaphase, and anaphase, the interzone spindle during anaphase, and finally the phragmoplast during late anaphase and telophase. All of these microtubule-containing structures and, notably, their transitions from one to another have been observed in single live cells progressing through mitosis and cytokinesis.