Abstract

The mature embryo sac of Arundo formosana Hack. contains an egg apparatus composed of an egg cell and two synergid cells at the micropylar end, a central cell with two large polar nuclei in the middle, and a mass of 8 to 18 antipodal cells at the chalazal end. The egg apparatus shares a cell wall with the central cell at the micropylar end and there is only a plasma membrane surrounding at the chalazal end. The cytoplasm of the egg is rich in mitochondria, starch-containing plastids and oil drops. Two synergid cells are very similar and strong polarized; mitochondria are distributed at the micropylar end and surrounding the filiform apparatus; plastids are only distributed at the chalazal end; and dictyosomes and dilated ER vescicles are numerous. The central cell has a complex organized cytoplasm that is rich in organelles; the two polar nuclei are partially fused; and many ingrowth walls occur adjacent to the nucellus. The antipodal cells contain a large amount of ER and ribosome. Plasmodesmata are present in the cell wall between the embryo sac cells, but not adjacent to the nucellus. After pollination, the egg shows a considerable increase in polarity. The persistent synergid cell retains its original constitution and the degenerated synergid cell is filled with the electron dense materials. The numberof dictyosomes and the quantities of oil drops and starch increase in the central cell. In the antipodal cells, most of the rough ER becomes parallel with the cell ealls; some dense-staining particles may be present between the plasma membranes and the cell walls; and the ingrowth walls occur adjacent to the nucellus.

中文摘要

台灣蘆竹(Arundo formosana Hack.)成熟之胚囊含有一位於珠孔端之卵器(由一個卵細胞和兩個助細胞組成)，中間位置為具有兩個大極核之中央細胞和於合點端有8至18個反足細胞群。卵器於珠孔端有細胞壁，而於合點端僅有細胞膜包圍著。卵細胞之細胞質含有許多粒線體，含澱粉之顆粒與油滴。兩個助細胞頗為類似且其內含物分布有明顯之極性；粒線體分布於珠孔端且圍繞著絲狀器；兩個極核部分癒合，而中央細胞與珠心細胞接壤處有許多內凸之細胞壁。反足細胞含大量之內質網和核醣體。原生質絲存在於胚囊細胞之細胞壁，而在胚囊細胞與珠心細胞間之細胞壁則無。受粉後，卵之極性增加。宿存助細胞維持原有構造，而瓦解助細胞則瓦解且充滿於電子顯微鏡下呈濃密之物質。中央細胞內之高基氏體數目和油滴與澱粉數量皆增加。反足細胞內大部分粗質內質網成為平行細胞壁排列；於細胞膜與細胞壁之間有許多染色濃之小顆粒；反足細胞與珠心細胞之接壤處亦有內凸之細胞壁。