莼菜绒毡层细胞发育的超微结构变化

莼菜（Ｂｒａｓｅｎｉａ ｓｃｈｒｅｂｅｒｉＧｍ ｅｌ）绒毡层细胞在小孢子母细胞时期，质体出现变形，淀粉粒消失．减数分裂期，绒毡层细胞中有丰富的高尔基体，内质网，核糖体和线粒体．随着细胞的发育，细胞壁呈胶质状态，胞间连丝断离，细胞间发育出现不同步现象，核糖体开始解体形成电子密度高的球状体．单核小孢子时期，质体积累淀粉增多，细胞内部微结构开始解体．经观察，绒毡层细胞壁的融解物质参与了小孢子外壁的形成，核糖体形成的高电子密度球状体沉积小孢子外壁腔隙中形成外壁蛋白．绒毡层细胞中淀粉粒积累与消失是小孢子正常发育的必然结果．

Ultrastructural Changes in the Development of Tapetal Cells of Brasenia schreberi Gmel

The plastids of tapetal cells of B. Schrebeti appear changes in shape apparently and the starch grains of cells disappear in microspore mother cell stage. During meiotic cell division stage, there are abundant Golgi bodies, endoplasmic reticulum, ribosomes and mitochondria in the tapetal cells. With the development of cells, the cell walls show agglutination, plasmodesmata break down, asynchronous condition occur in cell development, the ribosomes begin to dissociate and high electronic dense globules are formed. In the uninucleate microspore stage, deposition of starch on plastids increase, the microstructures of tapetal cells begin to dissociate. According to our observation, the dissolved materials of wall of tapetal cells are added to exine of microspores, the high electronic dense globules formed by ribosomes deposit to the cavities of microspore exine forming the exine protein. The deposition and disappearance of starch guains on tapetal cells is the result of microspore normal developing.