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作 者 ：Mu Xi-jin, Wang Fu-hsiung and Wang Wen-ling

Keywords:Pulsatilla chinensis, Tapetum, Peritapetal membrane, Ubisch body,

Abstract: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 ceils. 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 Compositae and that of secretory tapetum reported in Pinus banksiana. Heslop-Harrison and Gupta et al. had conceded that the tapetal and peritapetal membrane belong to the general class of sporopollenin. On the contrary in P. chinensis the sporopollenin 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 body is short necked flask shaped and their size is very similar. Ubisch body is either single or 2–5 in a group, resulting in compound bodies. When the Pro-Ubisch body is still within the tapetal cell it shows positive fluorescent reaction, while it eomletely unstains with Teluidine blue O. So Authors infer that the sporopollenin precur- sors may have permeated through Pro-Ubisch bodies. Finally, How sporopollenin precursor is synthesized in the tapetal cells, transported to pollen locula and polymerized into the sporopollenin on pollen, Ubisch body and peritapetal membrane? Future works along these problems may yield fruitful results.

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