薏苡种子胚芽鞘细胞的结构

Structure of Coleoptile Cells of Seed in Coix laryma jobi

观察了薏苡（Ｃｏｉｘｌａｃｒｙｍａ－ｊｏｂｉ）浸泡种子胚芽鞘的结构。胚芽鞘由外、内表皮薄壁组织及２个侧位的维管束组成。在外表皮两处，观察到径向壁不连续的细胞群，它们实际是合胞体。薄壁细胞含丰富的核糖体，内质网小泡和线粒体，说明代谢活动已经活跃。初生纹孔场内有胞间连丝，显示细胞间已存在物质的共质运转。初生壁上有许多来源于内质网的小囊泡，在胚芽鞘生长时，这些小囊泡可能参与细胞质膜的扩大，适应细胞的生长。核膜不连续，或可能有利于核与细胞质的物质交换。核仁偏向核膜，具核仁组织者的核仁还与无核膜部位相近的核膜相连。胚芽鞘细胞富含蛋白质体、脂体。薄壁细胞还含淀粉粒，所含蛋白质体有两种类型。

The structure of coleoptile cells of soaked seeds in Coix lacryma-jobi was examined. The coleoptile consists of outer and inner epidermis, parenchyma and two peripherally located vascular bundles. In two places of the outer epidermis, some cells have discontinuous radial walls forming a syncytium. The ribosomes, mitochondria and endoplasmic reticulum vesicles are abundant in parenchyma cells. The results suggest that the metabolism in the cells has become active. The plasmodesmata in the primary pit fields indicate that a synplastic pathway is present between parenchyma cells. There are many vesicles originated from endoplasmic reticulum on the primary walls. These vesicles may be involved in the enlargement of the plasma membrane to adapt cell growth during the coleoptile growing. The nuclear membrane is discontinuous. This may facilitate the substances exchange between nucleus and cytoplasm. The nucleolus is located near to nuclear membrane and the nucleolus with nucleoius organizer is connected with the nuclear membrane close to the region lack of membrane. Coleoptile cells are rich in protein bodies and lipid bodies, besides,the parenchyma cells contain starch grains.Two types of protein bodies are present in the parenchyma cells.