Yoon Chul Jong, Kim Ki Woo
Cell Morphology Institute, Seoul 157-790, Republic of Korea.
Micron. 2008 Oct;39(7):825-31. doi: 10.1016/j.micron.2007.12.011. Epub 2008 Jan 6.
Fine structure and tissue substitution by minerals were investigated in silicified woods from Madagascar and Indonesia by scanning electron microscopy and X-ray microanalysis. The silicified woods maintained the exterior morphology of once grown trees and showed typical inner structures of conifers. Radial planes of the silicified wood from Madagascar revealed tracheids as a major component of the axial system in the secondary xylem. Tracheids were mainly characterized by numerous bordered pits where a thickening in the middle (torus) was surrounded with the membrane (margo). The torus appeared to contrast with the fibrillar network of the margo. As a component of the axial system in the secondary phloem, sieve elements were found to have many sieve pores that were filled with seemingly crystalline materials. To correlate the colors of the silicified wood from Indonesia with elemental composition, energy-dispersive X-ray spectrometry was employed in this study. Silicon was present as a basic component of the silicified wood. Calcium and iron were detected from red-colored regions, whereas magnesium was found in blue-colored regions. These results suggest that tissues of silicified woods had been substituted by minerals over the past period, while retaining the inherent morphology of the tree species. Scanning electron microscopy and X-ray microanalysis could be applied to unravel structural details and composition of plant fossils in palaeobotany.
通过扫描电子显微镜和X射线微分析，对来自马达加斯加和印度尼西亚的硅化木的精细结构和矿物质组织替代情况进行了研究。硅化木保留了曾经生长树木的外部形态，并显示出针叶树典型的内部结构。来自马达加斯加的硅化木的径向平面显示，管胞是次生木质部轴向系统的主要组成部分。管胞的主要特征是有许多具缘纹孔，其中间加厚部分（纹孔塞）被膜（纹孔膜）包围。纹孔塞似乎与纹孔膜的纤维状网络形成对比。作为次生韧皮部轴向系统的组成部分，筛管分子被发现有许多充满看似晶体物质的筛孔。为了将来自印度尼西亚的硅化木的颜色与元素组成相关联，本研究采用了能量色散X射线光谱法。硅是硅化木的基本组成成分。在红色区域检测到钙和铁，而在蓝色区域发现了镁。这些结果表明，在过去的一段时间里，硅化木的组织被矿物质替代，同时保留了树种的固有形态。扫描电子显微镜和X射线微分析可用于揭示古植物学中植物化石的结构细节和组成。
