摘要
橡胶树（ＨｅｖｅａｂｒａｓｉｌｉｅｎｓｉｓＭｕｅｌ－Ａｒｇ，）成熟胚囊的超微结构电镜观察结果表明：（１）卵细胞具明显的极性，细胞核和细胞质的大部分分布在最近合点端，珠孔端的２／３为大型液泡所占据。细胞壁不完全，其合点端没有细胞壁，助细胞和中央细胞在这一区域也没有细胞壁；因此，卵细胞与中央细胞，卵细胞与助细胞，或助细胞与中央细胞之间，只有质膜作为分界。细胞器的大部分分布在细胞核周围细胞质中，其中质体，线粒体和核糖体的含量较多，但内质网不发达，高尔基体数量十分稀少，且质体发育程度低，只有少量片层。上述结构表明卵细胞的代谢作用是不活跃的。（２）助细胞的珠孔端壁发育形成明显的丝状器。细胞器十分丰富，内质网发达，且大部分的细胞器较集中的分布在靠近珠孔端的细胞质中，表明助细胞具有活跃的分泌功能。（３）中央细胞由于具大型的液泡，细胞质被挤压到细胞的四周，形成一薄层；两个极核位于靠近卵器的部位，以后它们将相互发生融合；细胞器比较丰富，同时含有较多量的淀粉粒和油滴；内质网，特别是位于与卵器靠近的边界区域中的切面上呈一些长形的，平行排列的成对膜层结构。由于共同无壁区域的存在，中央细胞和卵器在功能上有密切联系。（４）反足细胞的特?
The ultrastructure of mature embryo sac of Hevea Brasiliensis Muel-Arg. was studied.The egg is a highly polarized cell, the nucleus and much of the cytoplasm are located at theextreme chalazal end,and2/3 of the micropylar end is occupied by a large vacuole; The wallsurrounding the egg cell is incomplete;the cell at the1/3 of the chalazal end, the neighbour-ing parts of synergids and the central cell bear no wall; and only plasma membranes exist asa boundary between egg and central cell, egg and synergid,or synergid and central cell.Most of the organelles are distributed perinucleusly, among which the plastids,mitochondriaand ribOsomes are quite numerous, the ER and dictyosome scarce and plastids poorly devel-oped with a few lamellae. The egg is an inactive cell based on its above ultrastructure, Thewall surrounding the synergid proliferates evidently into filiform apparatus at the micropylarend. There are abundant organelles and masses of ER in the synergid cytoplasm, and mostof the drgatielles are distributed at the micropylar part, suggesting an active secretory func-tion of synergid. In the central cell the cytoplasm is pressed by the large centrally locatedvacuole to a thin peripheral layer, and the polar nuclei situated near the egg apparatus willpartially be fused with each other later. There are plenty of organelles and massive lipid dro-plets and starch grains in the central cell cytoplasm, and the ER forms some long narrowparallel strands of cisternae especiallyin the region bordering the egg apparatus. There is aclose relation betvveen central cell and egg apparatus due to the presence of a common wallless region. The antipodal cells have a complete wall and the wall proliferates lightly intonodulous-like structure resembling to that of the transfer cell; the nucleus, being single,oc-cupies a central position; and the cytoplasm is of high electron density, the organelles boun-tiful and ER well developed. The central cell and antipodal cell like the synergid are quite ac-tive in metabolism.
出处
《热带作物学报》
CSCD
1995年第1期10-16,共7页
Chinese Journal of Tropical Crops
基金
国家自始科学基金
关键词
橡胶树
胚囊
超微结构
Hevea brasiliensis embryo sacultrastructure
