水稻雌蕊与胚囊中钙的超微细胞化学定位

用焦锑酸盐沉淀法对水稻（OryzasativaL．）授粉前后雌蕊和胚囊中的钙进行了超微细胞化学定位。结果表明，柱头乳突细胞表面和花柱薄壁细胞中均含钙沉淀；开花前1d，整个胚囊中含钙较少，两个助细胞中钙分布无差异；临近开花时，1个助细胞已退化，其钙含量明显增加；开花后6h，胚囊已受精，退化助细胞中钙含量进一步增加;受精前卵细胞中钙主要分布在液泡中，核和胞质中较少；受精后，其钙含量明显增加，主要分布于核中。重点讨论了钙与助细胞退化和卵细胞激活的关系。

Ultracytochemical Localization of Calcium in the Gynoecium and Embryo Sac of Rice

Potassium pyroantimonate precipitation method was used for ultracytochemical localization of ealcium in rice (Oryza sativa L.) stigma, style, ovary and embryo sac before and after fertilization. To identify the nature of the pyroantimonate deposits, the energy-dispersive X-ray microanalysis(EDXA) was employed andthe deposits observed were proved as calcium pyroantimonate. Transkmission electron microscopic observations revealed that abundant deposits were present at the surface of stigma papillae and parenchymatous cells ofstyle. One day before anthesis, when the embryo sac was immature and contained a few deposits, calcium distribution showed no difference between two synergids. By the time just prior to anthesis, one of the synergidsthat had degenerated accumulated more calcium than before, and than the other synergid. Six hours after anthesis at time when double fertilization had finished, the calcium deposits in the degenerated synergid increased. Before fertilization, the deposits in the egg cell were mainly localized in the vacuoles, whereas fewdeposits could be observed in the nucleus and eytoplasm. After fertilization, the amount of calcium increased dramatically in the zygote, espeially in its nucleus. The results are discussed in relation to the role of calciumin mediating synergid degeneration and egg activation.Keywoads: Rice, Calcium, Ultracytochemistry, Gynoecium, Synergid, Egg cell