Ref ID : 7282
Robert Edward Lee, Cynthia Miller-Hughes, and Paul Kugrens; Ultrastructure of Mitosis and Cytokinesis in the Colorless Flagellate Katablepharis ovalis Skuja. J.Eukaryot.Microbiol. 40(3):377-383, 1993
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Mitosis and cytokinesis in Katablepharis ovalis, a colorless flagellate, was investigated. Two new flagella are produced prior to prophase, resulting in a motile quadriflagellate cell during mitosis. The inner array of microtubules of the feeding apparatus disappears before prophase begins. The nuclear envelope disperses during prophase, apparently being converted into rough endoplasmic reticulum. The chromatin condenses and the nucleolus disperses with spindle microtubules appearing oriented perpendicular to the longitudinal axis of the cell. At metaphase, the chromatin is condensed as a single disc-shaped mass and rough endoplasmic reticulum flanks the chromatin mass on each side. Groups of spindle microtubules pass through tunnels in the rough endoplasmic reticulum and through electron-translucent areas of the chromatin. The spindle microtubules end at a number of minipoles in the cytoplasm. Vesicles, ribosomes, mitochondria and endoplasmic reticulum migrate among the spindle microtubules. There is no polar body or any electron-dense area associated with the spindle poles. The basal bodies of the flagella remain attached to the axonemes and do not participate in mitosis. In anaphase, the chromatin separates and migrates to the poles. During telophase, the nuclear envelope reforms from the rough endoplasmic reticulum and the nucleoli reappear. The spindle microtubules are persistent during telophase. Cytokinesis occurs by longitudinal fission, starting at the anterior end and progressing posteriorly. Cytokinesis may be driven by elongation of the spindle microtubules since there is no visible structure associated with the furrowing.