Department of Botany, University of Wisconsin, 53706, Madison, Wisconsin, USA.
Planta. 1972 Sep;109(3):193-210. doi: 10.1007/BF00387084.
Portions of the hypocotyls of 16-day-old Cucurbita maxima plants, from which the cotyledons and first foliage leaves had been removed 2 days earlier, were fixed in glutaraldehyde and postfixed in osmium tetroxide for electron microscopy. In well over 90% of the mature sieve elements examined the P-protein was entirely parietal in distribution in both the lumina and sieve-plate pores. In addition to the parietal P-protein, the unoccluded sieve-plate pores were lined by narrow callose cylinders and the plasmalemma. Segments of endoplasmic reticulum also occurred along the margins of the pores.
16 天大的南瓜植株下胚轴的部分组织被固定在戊二醛中，两天前已去除子叶和第一片真叶，然后用四氧化锇后固定，用于电子显微镜观察。在检查的 90%以上成熟的筛管中，P 蛋白在腔和筛板孔中完全呈壁分布。除了壁 P 蛋白外，无堵塞的筛板孔还被狭窄的胼胝质圆柱体和质膜所包围。内质网的片段也沿着孔的边缘发生。
