薏苡胚乳传递细胞的超微结构

传粉后１０ ｄ，薏苡（Ｃｏｉｘ ｌａｃｒｙｍ ａ－ｊｏｂｉＬ．）颖果基部胚乳最外层传递细胞具长而多的壁内突，第二层细胞的壁内突较第一层的短而少，均具瓣裂的细胞核、丰富的线粒体、粗糙内质网、核糖体、产生小泡的高尔基体及与壁内突质膜相连的、含深色物质的囊泡。线粒体分布于壁内突附近或其间。授粉后２５ ｄ，第一、二层细胞壁内突发达，几乎充满了细胞，但细胞器可见。第四层传递细胞具树枝状及网状的壁内突，大量线粒体、具质体膜的淀粉粒、脂体存在壁内突附近或壁内突的间隙内。高尔基体常见，仅见很少的片段内质网。第五层传递细胞具短的壁内突、较大的淀粉粒及许多小蛋白质体。两个时期的第一、二层细胞内均未观察到胞间连丝。授粉后２５ ｄ，第四层及以上的传递细胞的细胞壁和呈网状的壁内突均含有胞间连丝。还讨论了各种细胞器的作用及各层传递细胞的功能

ULTRASTRUCTURE OF TRANSFER CELLS IN ENDOSPERM OF COIX LACRYMA JOBI

Special attention was paid to the ultrastructure of transfer cells (TCs) in different locations of basal endosperm in Coix lacryma jobi at 10 and 25 days after pollination. At 10 days after pollination, TCs of the outermost layer had long wall ingrowths (WIs) whereas those of the second layer possessed fewer and shorter WIs. In both layers TCs had a lobed nucleus, abundant mitochondria, rough endoplasmic reticulum (RER), ribosomes, and a certain number of dictyosomes and vesicles which contained dense substance connected with plasma membrane of WIs. Mitochondria were located near or between WIs. The distribution of organelles in TCs of the second layer was similar to that of the outermost layer. Mitochondria had well defined cristae and dictyosomes and RER seemed more numerous than in TCs of the outermost layer. At 25 days after pollination, TCs of the outermost and the second layer were almost filled with WIs but the organelles were recognizable. TCs of the fourth layer had branched and network like WIs, many mitochondria, starch grain within plastids and lipids locating near WIs and in the interstices of WIs. Dictyosomes were frequently found but less RER fragments were seen. TCs of the fifth layer with short WIs contained large starch grains and small protein bodies. Plasmodesmata were not observed in the walls of TCs of the outermost and second layer at both 10 and 25 days after pollination but were found in the walls of TCs of the fourth and upper layers and also in the network like WIs at 25 days after pollination. The roles of the organelles and functions of TCs of different layers were discussed.