去包埋剂制片术揭示小麦珠被组织中微丝的跨胞分布

REVEALLING THE TRANSCELLULAR DISTRIBUTION OF MICROFILAMENTS IN INTEGUMENT BY EMBEDMENT-FREE SECTION METHOD IN TRITICUM AESTIVUM

以DGD(diethylene glycol distearate)包埋、去包埋剂制片法,结合常规电镜制备术,观察研究了小麦珠被组织中胞间连丝的结构与分布特征及其与微丝的关系。试验结果表明,同层珠被细胞间壁上胞间连丝的分布密度比上下层珠被间的要显著地高得多;珠被中胞间连丝保持固有的正常结构,孔径30—40 nm,变动幅度不大,观察不到如作者以前在小麦珠心和胚乳中所见的那种胞间连丝经结构修饰而扩大、转变为开放态的景象。对去包埋剂制片的观察进一步揭示,从胞质骨架网络表层有纤细微丝以分散状向外伸展突入分界壁,时而可见各个微丝横贯分界壁而连接相邻骨架网络的图象。联系珠被中正常胞间连丝结构的稳定性与各个微丝以分散状跨越分界壁,讨论了微丝参与胞间连丝结构的可能性与可能模式。

By means of Triton X-100 extraction and embedment-free sections combined with electron microscopic observations the structure and distribution of plasmodes-mata in relation to the arrangement of microfilaments were studied in integument of developing wheat ovules. Frequency of plasmodesmata at the boundary wall of cells in the same layer is apparently higher than that at the wall between upper and lower layers of integument tissue. Plasmodesmata in integument are 30-40 nm in diameter, and always keep their original archtecture not exhibiting any structural modification, though the latter event often occurs in nucleus and endosperm and had been described in our earlier re-portsp. Electron microscopic inspections of embedment-free sections revealed that a lot of microfilaments lying on the surface of cytoskeleton frame often individually extrude into the cell wall. Clear images showing the individual microfilaments traversing the wall boundary and connecting the cytoskeleton frames of adjoining cells also can be caught. Based on the above mentioned results a suggested model of microfilaments being the structural constituent of normal plasmodesma was postulated.