01763nas a2200217   4500008004100000245012400041210006900165260001200234300001300246490000800259520103800267653001201305653001701317653001201334653001301346653002101359653001601380100001601396700001701412856011601429       1984                        eng d00aPlastid apportionment and preprophase microtubule bands in monoplastidic root meristem cells of Isoetes and Selaginella0 aPlastid apportionment and preprophase microtubule bands in monop  c1984///  a95 - 1030 v1233 aUltrastructural observations on monoplastidic root tip cells of Isoetes and Selaginella demonstrate two important phenomena associated with preprophasic preparation for mitotic cell division, 1. the preprophase band and 2. precise orientation of the dividing plastid relative to the preprophase band. Both of these phenomena accurately predict the future plane of cell division. The plastid divides in a plane parallel to the spindle and each cell inherits a single plastid which caps the telophase nucleus. When succesive transverse divisions occur, the plastid migrates prior to prophase from a position near an old transverse wall to a lateral position in the cell. The plastid is oriented with its median constriction precisely intersected by the plane of the preprophase band. When a longitudinal division follows a transverse division, the plastid remains in its position adjacent to an old transverse wall where it is bisected by the plane of the longitudinally oriented preprophase band microtubules. © 1984 Springer-Verlag.10aIsoetes10aMicrotubules10aMitosis10aPlastids10aPreprophase Band10aSelaginella1 aBrown, R.C.1 aLemmon, B.E.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0002906412&partnerID=40&md5=b3cea711cdf0bf1636ca85aff68bf55301881nas a2200229   4500008004100000245008100041210006900122260001200191300001400203490000800217520117800225653001301403653001201416653001601428653001201444653001701456653001201473100001701485700001601502700001701518856011601535       1992                        eng d00aMicrotubule arrays during mitosis in monoplastidic root tip cells of Isoetes0 aMicrotubule arrays during mitosis in monoplastidic root tip cell  c1992///  a123 - 1330 v1673 aMitosis in monoplastidic root tip cells of Isoetes was studied by fluorescence (confocal laser scanning microscopy) and transmission electron microscopy. The two major components of division polarity, spindle axis and division site, are established more or less simultaneously in preprophase. Morphogenetic plastid migration results in positioning of a daughter plastid at each pole of the future spindle. Concomitant with establishment of the spindle axis, the division site is marked by a girdling band of mirotubules (preprophase band). Endoplasmic microtubules interconnect the polar plastids and preprophase band suggesting a mechanism for communication and final alignment of spindle axis and division site. As in other monoplastidic cells, the spindle appears to emanate from the plastids. In telophase, the focus of microtubules shifts to the reforming nuclei as the phragmoplast is initiated. Microtubules which continue to emanate from plastids are incorporated into the phragmoplast as it expands beyond the interzonal region. Cortical microtubules are restored in a random fashion before assuming a transverse arrangement in interphase. © 1992 Springer-Verlag.10aConfocal10aIsoetes10aMicrotubule10aMitosis10aMonoplastidy10aPlastid1 aCleary, A.L.1 aBrown, R.C.1 aLemmon, B.E.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0000314665&partnerID=40&md5=9574acecdc52183ede5fc00cd7f20758