中文摘要：

利用切片技术与整体解剖的方法观察了银杏胚乳游离核期的发生,分裂、增殖以及胚乳细胞化期的过程,采用纤维素酶解法分析了胚乳细胞数目的增殖动态。结果表明：银杏胚乳游离核期分裂增生约为授粉后5~30 d、胚乳细胞化期约为授粉后30~65 d;银杏雌配子体有丝分裂产生大量游离核,结构呈球形,直径平均为2~4μm,最初分布于细胞质的中央,随着中央液泡的扩大,细胞质连同游离核被挤向四周;游离核分裂到约4 000~5 000个时即进入细胞化期,首先在核周围形成一层开放细胞,靠近中央大液泡一侧无细胞壁,周边的细胞向心游离生长,直至所占空腔被胚乳细胞完全填满,胚乳细胞化完成;银杏胚乳细胞数目呈现＂S＂形变化趋势。前期胚乳细胞数目的增殖较慢,在授粉后40~55 d胚乳数目急剧上升,至授粉后65 d胚乳数达最大,胚乳细胞分裂基本停止,其数目趋于稳定。综上所述,银杏游离核的分裂及增殖具有独特性状,增加胚乳细胞数目对银杏种仁发育具有重要意义。

英文摘要：

Using slicing and total dissection techniques,we observed the process of division and proliferation of free nuclei,and endosperm cellularization in Ginkgo biloba L. We analyzed the proliferate development of endosperm cells by the means of disassembling endosperm with the cellulose enzymes. The results showed that the division and proliferation of free nuclei occurred 5- 30 days after pollination and cellularization occurred about 30- 65 days after pollination. The female gametophyte mitosis resulted in many free nuclei,which was spherical shape with the average diameter of 2- 4 μm. At the initial stages,the free nuclei distributed in the central cytoplasm. However,with the volume of central vacuoles increasing,cytoplasm and nuclei were pushed to around. Then,one layer of opening cells that had no cell wall at the side near central vacuole formed in the periphery after the formation of about 4 000- 5 000 nuclei. Cells around grew centripetal and dissociative,till cavum was filled with endosperm cells and the cellularization was finished. The proliferate development of the endosperm cells took on ＂S＂-shape curve,which was slowly at the early stage after pollination,then it changed faster during 40- 55 days after pollination,and the number of endosperm cells reached the maximum at 65 days after pollination. Afterwards,the number of endosperm cells did not significantly changed. Therefore,the division and proliferation of free nuclei have unique traits, and the number of endosperm cells play a significantly role in the development of seeds in G. biloba.