Studies on the Relationship between the Degree of Juvenility and Cell Ultrastructure in Prince Rupprect Larch （Larix Principis—rupprechti） Ⅰ.Embryo,annual shoots in 3—year old and 12—year old trees

摘要

＜正＞ The ultrastructure of embryo cells and phloem parenchyma cell of annual shoots from 3—year old and 12 —year old trees in Prince Rupprect Larch were studied by Transmission Electron Microscopy.In embryo cells, many organelles were not differentiated, the plastids only existed in the form ofproplastids,there were numerous,almost empty,vacuoles which were equal in volume and equally distributed.Plasmodesmata were not observed. In the cells of 3—year old trees,there were two kinds of plastids ,themitochondrial differentiation was in the initial stage,the vacuoles were less than those in embryo cells andwere various in volume,and there were few plasmodesmata. In the cells of 12—year—old trees,there werethree kinds of plastids with an obvious thylakoid lamellae structure,the small number of large vacuoles withrich contents existed on the form of secondary lysosomes, there were also plasmodesmata with an obvioustube —shaped structure. There was simpler ultrastructure showing a higher degree of juvenility in embryocells,and more complicated ultrastructure showing lower degree of juvenility in the cells of the 12—year oldtrees than in those of the 3—year—old trees. A close relationship was shown between the cell ultrastructureand the degree of juvenility in the trees .