Key message

In some circumstances vessel elements, both broad and narrow, enlarge only symplastically in tangential direction. Rays play a special role in regulating intrusive enlargement of vessel elements.

Abstract

The aim of this study was to analyse relations occurring between vessel elements and surrounding cells, i.e. susceptibility to separation of walls of cells occurring in the vicinity of vessel elements, with regard to their type—cells of the axial/radial system. On the basis of separation/lack of separation of cell walls, and thus change in cell contacts/lack of change in cell contacts, we have estimated the contribution of particular types of growth—intrusive and symplastic—in the formation of vessel elements in: Acer pseudoplatanus, Betula pendula, Catalpa bignonioides, Quercus robur and Robinia pseudoacacia. Striking differences in susceptibility to separation of periclinal walls of axial and ray system cells were noticed. Periclinal walls of axial system cells were easily separated, even in cells which were not directly adjacent to vessel elements. Continuity of ray cells was maintained even in cases when the vessel element enlarged directly between two rays. It seems that the direct vicinity of ray increases the contribution, as well as the range of symplastic growth in a tangential direction during vessel element formation. Growth of a vessel element in a tangential direction has been described as intrusive so far. A vessel element seems to enlarge only symplastically, when derived from a mother cell located directly between two rays. Observed differences in susceptibility to separation of cell walls indicate the important role of rays in regulating intrusive expansion of vessel elements.

中文翻译：

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射线妨碍血管元素的侵入性生长

关键信息

在某些情况下，宽和窄的血管元素仅在切线方向上对称地增大。射线在调节血管元素的侵入性扩大中起特殊作用。

抽象

这项研究的目的是分析血管元件和周围细胞之间发生的关系，即就其类型（轴向/径向系统的细胞）而言，对分离在血管元件附近的细胞壁的敏感性。基于细胞壁的分离/缺乏，因此细胞接触的变化/细胞接触的变化的缺乏，我们估计了特定类型的生长（侵入性和共生性）在以下血管元素形成中的作用：伪槭，桦木，al，栎和刺槐。注意到轴向和射线系统细胞的周缘壁分离敏感性的显着差异。即使在与血管元件不直接相邻的细胞中，轴向系统细胞的周壁也很容易分离。即使在两个射线之间直接放大血管元素的情况下，射线细胞的连续性也得以保持。似乎射线的直接邻近增加了血管元素形成过程中的贡献，以及切线方向上共生增长的范围。到目前为止，已将血管元素沿切线方向的生长描述为侵入性的。当血管元素从直接位于两条射线之间的母细胞派生时，似乎仅是共生地增大。