【摘要】 用焦锑酸盐沉淀法对鹤顶兰(Phaius tankervilliae)胚囊发育过程中的Ca2+状态进行超微细胞化学定位。观察结果发现:功能大孢子时期,珠孔端的胚囊壁上开始出现小颗粒的Ca2+沉淀,但功能大孢子细胞内未见明显的Ca2+标记;四核胚囊时期胚囊壁上的Ca2+沉淀明显增多,液泡膜上有Ca2+沉淀出现,珠孔处的Ca2+沉淀颗粒较大;成熟胚囊时期,胚囊壁上的Ca2+沉淀进一步增多,且胚囊内Ca2+分布明显增多,且极性明显,珠孔端助细胞、卵细胞比合点端反足细胞有更多的Ca2+沉淀。鹤顶兰成熟胚囊内Ca2+积累的来源有:(1)在胚囊成熟前主要由珠被细胞、珠细胞通过胞间连丝向胚囊运输;(2)以沉淀有大量Ca2+的小泡形式跨过胚囊壁进入胚囊。更多还原

【Abstract】 Ultracytochemical localization of calcium in embryo sac of Phaius tankervilliae(Aiton) Bl. was carried out using potassium pyroantimonate precipitation method. Results of Ca2+ distribution during embryo sac development are as following:(1) Megasporocyte stage:There is no Ca2+ precipitation in the megasporocyte,nucellar cell and micropyle; (2) Functional megaspore stage:Small particles of Ca2+ precipitates appear on the embryo sac wall at the micropylar end,but no apparent Ca2+ can be found in the functional megaspore; (3) 4-nucleate stage:There are significant increase of Ca2+ precipitation on the embryo sac wall and large grains of the precipitates in the micropyle,while a little starts to appear on the membrane of vacuole; (4) 8-nucleate embryo sac stage:Ca2+ precipitation continuously increases on the embryo sac wall. Distribution of Ca2+ in embryo sac shows strong polarity. More Ca2+ precipitations are observed in the synergids and the egg cell than the antipodal cells. Accumulation of Ca2+ precipitation is achieved by (1) transferring Ca2+ to embryo sac through the plasmodesmata between the nucellar cells,which mainly occurred at the chalaza end before the embryo matured; (2) forming large amounts of small bubbles of Ca2+ precipitation,which can cross embryo sac wall to enter embryo sac.更多还原