摘要
白头翁绒毡层为分泌型。发育过程分为:发生一分化,生长-合成和分泌-解体3个阶段。第1阶段,绒毡层细胞的形态结构和组织化学特征同造孢组织和花粉母细胞的大体一致,所不同的是大量积累淀粉和形成少量原乌氏体。第2阶段为重要的合成时期;细胞体积膨大,具多倍体双核或畸形核,蛋白质大量合成,淀粉水解;原乌氏体和孢粉素荧光物质大量累积。第3阶段为分泌最活跃时期,裸细胞在执行分泌功能上起着重要作用。原乌氏体,荧光物质,碳水化合物,或许包括分解胼胝质壁和纤维素壁酶等成分均在裸细胞阶段排出。周绒毡层膜、乌氏体和花粉外壁均属于孢粉素性质的结构。根据周绒毡层膜的外切向位置和结构,初步结论:它可能是绒毡层细胞质膜向着药壁中层一面的残存部分,而膜内表面上的孢粉素纹理则是后来添加的。乌氏体的基本形态为短颈烧瓶状,单个或2—5个组成复合结构。本文对绒毡层、绒毡层膜和乌氏体的功能,及孢粉素的转运和聚合等问题进行了讨论。
Tapetum of Pulsatilla chinensis is of secretory type.Its development proceeds rapidly in following sequence:(1)The stage of initiation-differentiation.At this stage cytological and histochemical features have been described in detail in this paper.(2)The stage of growth- synthesis:This stage appears to be the most important anabolic phase during the development of the tapetum.The salient features are that the tapetal cells become relatively enlarged and form two polyploid nuclei or aberrent polyploid nuclei resulting in synthetizing maximum proteins,fluorescing substances and maximum fluorescent Pro-Ubisch bodies in the tapetal cytoplasm.(3)The stage of secretion-disorganization:After the disintegration of the tapetal wall the enlarged naked cells appear at once.This is an important secretion period in which Pro-Ubisch bodies as well as all other fluorescing substances,carbohydrate or some enzymes are released into anther loculus.The naked cell layer becomes disorgnized until the beginning divition of the pollen grains into two cells. As to peritapetal membrane of P.chinensis,mainly based on the membrane being on the outer side of the tapetum enclosing both the pollen,tapetal cytoplasm and Ubisch bodies,and the cellular configurations facing the pollen, Authors postulate that peritapetal membrane might be survival of the cytoplasmic membrane of tapetal cells.However,the peritapetal membrane of P.chinensis is similar to that of plasmodial tapetum reported in certain Compo- sitae and that of secretory tapetum reported in Pinus banksiana. Heslop-Harrison and Gupta et al.had conceded that the tapetal and peritapetal membra- ne belong to the general class of sporopollenin.On the contrary in P.chinensis the sporopolle- nin property Of peritapetal membrane is only confined to its inner surface.But the thin mem- brane itself with the reticulate sporopollenin attched on its inner side appears negative staining reactions for sporopollenin though it has an ability to resist the acetolysis as well. In P.chinensis the Ubisch
基金
中国科学院科学基金资助
