MITOSIS AND MICROTUBULE ORGANIZATIONAL CHANGES IN ISOLATED GENERATIVE CELLS OF ALLEMANDA-NERIIFOLIA

The organizational changes of the microtubules of isolated generative cells of Allemanda neriifolia during division were followed using anti-alpha-tubulin and immunofluorescence microscopy. Generative cells were isolated from the pollen tubes after osmotic shock treatment. Immediately after isolation most of the cells remain either in early or late prophase. The shape of the cell changes from spindle to spheroidal. In early prophase the nuclear membrane of the cell appears intact and the cytoplasm full of reticulate microtubules of different shapes and thicknesses. Later, the nuclear membrane breaks up. After the nuclear membrane has broken up, the chromosomes scatter into the cytoplasm and mix with the microtubules. When cells enter metaphase, spindle microtubules form. Afterwards, in anaphase, sister chromatids separate and the spindle disappears. A new array of longitudinally oriented cage microtubules appears. As the cells enter early telophase, the cage microtubules disappear and an array of interpolar microtubules begins to form. Later, in some telophase cells the interpolar microtubules become highly elongated, but in others they soon disappear and become replaced by a thick band(s) (or sheet(s)) of microtubules in the midplane between the two clusters of chromosomes and the cell shape reverts back to spheroidal. In culture no phragmoplast junctions appear in any of the late telophase cells although they are present under the in situ condition (i.e. in pollen tubes).