Department of Biology, University of Dayton, Dayton, Ohio 45409.
Plant Physiol. 1969 Jan;44(1):45-54. doi: 10.1104/pp.44.1.45.
Anatomical and ultrastructural details of a translocating 10-cm leaf of sugar beet (Beta vulgaris L. var. Klein Wanzleben) were correlated with translocation rate data. The minor veins were found to be 13 times as extensive as the major veins and measure 70 cm/cm(2) leaf lamina. Measurements disclosed that a 33-mu length of minor vein services 29 mesophyll cells with the result that translocate moves an average of 73 mu or 2.2 cell diameters during transport from mesophyll cells to a minor vein. High-resolution, freeze-dry autoradiography revealed that assimilates accumulate in organelle-rich cells of the minor vein phloem. Correlation of phloem volume and loading rate for minor veins yielded an uptake rate of 735 mumoles of sucrose per g fresh weight of phloem. The arrangement and structural features of minor veins appeared to be consistent with the concept that vein loading precedes translocation.
对正在转运的 10 厘米甜菜（Beta vulgaris L. var. Klein Wanzleben）叶片的解剖学和超微结构细节与转运速率数据进行了相关分析。发现小叶脉比大叶脉宽 13 倍，面积为 70cm/cm(2)叶片层。测量结果表明，33μm 长的小叶脉为 29 个叶肉细胞提供服务，因此在从叶肉细胞向小叶脉转运过程中，转运物平均移动 73μm 或 2.2 个细胞直径。高分辨率、冻干放射自显影显示，同化物在小叶脉韧皮部富含细胞器的细胞中积累。韧皮部体积和装载速率的相关性表明，每克韧皮部鲜重的蔗糖摄取率为 735 微摩尔。小叶脉的排列和结构特征似乎与这样的概念一致，即叶脉装载先于转运。
