Ultrastructural characterization of the cytoplasmic channel formation between pollen mother cells of David lily

New insights into cytomixis: specific cellular features and prevalence in higher plants

“…For example, as in vivo monitoring of cytomixis in the wheat endosperm has demonstrated that a migrating nucleus constantly contacts a large number of filamentous structures attached to the nuclear envelope (Zhang et al 1990). An analogous pattern was observed in the lily microsporocytes at an ultrastructural level: microtubule-like elements were evident inside the CC and were connected with migrating organelles (Wang et al 2002). Nonetheless, immunofluorescence assay of the tubulin cytoskeleton in meiosis of the tobacco plants with a high rate of cytomixis failed to find any specific features in its dynamics or organization that would allow them to be associated with the intercellular nuclear migration (Sidorchuk et al 2007b).…”

“…At an ultrastructural level, researchers have observed migrations of nuclei through single or multiple CCs, chromatin condensation in CCs, restoration of its structure in the recipient cell, formation of micronuclei, and formation of the cell chains connected via migrating nuclei (Heslop-Harrison 1966;Whelan et al 1974;Feijo and Pais 1989;Wang et al 2002;Mursalimov and Deineko 2011). In addition, an ultrastructural examination allowed for discovery of the specific features of cytomixis, undetectable at the level of light microscopy.…”

“…In addition, an ultrastructural examination allowed for discovery of the specific features of cytomixis, undetectable at the level of light microscopy. In particular, it has been shown that no visual damages of nuclear envelope and chromatin are seen during cytomixis and that the nucleolus can change its shape and divide into parts to pass through CCs (Wang et al 2002;Mursalimov and Deineko 2011). …”

“…Their emergence in the cell wall allows the nuclei and other organelles to migrate from one cell to another. Unlike plasmodesmata, CCs have no internal structure, such as desmotubules and, as a rule, CCs are considerably larger than plasmodesmata; the CC diameter ranges from 50 to 3,500 nm (Heslop-Harrison 1966;Wang et al 1998;Wang et al 2002;Mursalimov et al 2010). In addition, CCs may occupy over 25 % of the cell surface (HeslopHarrison 1966).…”

“…3d), which covers cells until the tetrad stage; in this process, the primary CCs disappear (Wang et al 2002;Mursalimov and Deineko 2012). However, it has been shown that secondary CCs can be formed in the callose wall and the specific organelles-spherosome-like vesicles, containing the enzyme callase-are involved in this process (Mursalimov et al 2010;2013).…”