[The steps of mobile phragmoplast formation in meiosis with successive cytokinesis].

Previously non-described in literature abnormalities of phragmoplast formation in pollen mother cells of cereal haploids and allohaploids are reported. These abnormal phenotypes reveal and illustrate some steps of the process of phragmoplast formation in dividing plant cell, indicate a special regulation of their start, and confirm the information about the process obtained from other sources. The cytokinetic stage in plant cytoskeleton cycle is discussed.

Formation and function of phragmoplast during successive cytokinesis stages in higher plant meiosis.

Cytoskeletal rearrangements were studied during meiotic telophase in a number of monocotyledonous plant species. Wild type and abnormal meiosis (in wide cereal hybrids, meiotic mutants and allolines) was analyzed. It was found that central spindle fibers that move centrifugally, along with newly-formed MTs, are the basis of phragmoplast formation and function in PMCs of monocotyledonous plant species with successive cytokinesis stages. A model for centrifugal movement of the meiotic phragmoplast is proposed; this model is a modification of the corresponding process during B-anaphase.

[Dynamics of microtubular cytoskeleton in higher plant meiosis. VI. Mechanisms of the successive cytokinesis].

Intracellular morphological processes of successive cytokinesis in cereal pollen mother cells during normal and abnormal meiosis were studied. It was shown that the central spindle fiber system transforms into a phragmoplast at telophase. A model of centrifugal movement of the phragmoplast as a modification of B-anaphase has been proposed.

[Altering of phragmoplast orientation as a result of excessive centrifugal movement in the absence of cell plate].

The inability of phragmoplast to stop its centrifugal movement after reaching the mother cell membrane is described in abnormal meiosis with the arrest of cell plate formation. The excess of phragmoplast expansion leads to rotation of the whole telophase figure (phragmoplast with daughter nuclei) within the cell through 90 degrees. It has been suggested that this phenomenon may occur because of a the lack of signal stopping cytokinesis. Such a signal arises due to formation of daughter cell membranes.

[Dynamics of microtubular cytoskeleton in higher plant meiosis. IV. Middle prometaphase].

By means of morphological analyses of meiotic abnormalities in pollen mother cells of cereal distant hybrids, processes of cytoskeleton cycle at the middle prometaphase (chaotic stage) were studied. It was shown that elements of the bipolar spindle (central and opposite kinetochore fibres) are formed at the chaotic stage of meiotic prometaphase.

[Dynamics of microtubular cytoskeleton in higher plant meiosis. V. Late prometaphase. The general scheme of anastral spindle formation].

By means of morphological analyses of meiotic abnormalities in pollen mother cells (PMCs) of cereal wide hybrids, haploids and meiotic mutants, the processes involved in cytoskeleton cycle at late prometaphase (a sub-stage of transition from chaotic figure to bipolar spindle) were studied. A significance of the four processes of late prometaphase--axial orientation, lateral association, consolidation and convergance of spindle fibers--is discussed.

[Consolidation of cytoskeleton during plant spindle formation. I. Abnormalities of spindle integrity in meiosis]. / Konsolidatsiia tsitoskeleta pri formirovanii veretena deleniia v rastitel'noi kletke.

The process of formation of multiple spindles in mononucleate pollen mother cells during meiosis in general wide hybrids F1 and haploids is described. It is assumed that the abnormality may be caused by aberration of a special process at late prometaphase providing for the spindle consolidation.