花生受精前后胚囊的超微结构研究

AN ULTRASTRUCTURAL STUDY OF EMBRYO SAC IN ARACHIS HYPOGAEA BEFORE AND AFTER FERTILIZATION

开花后１～８ｈ，卵细胞合点端无壁，其质膜和中央细胞质膜之间有较宽间隙，两质膜均有间断处。细胞质主要分布在合点端，细胞器呈不活跃状态。一个助细胞合点端具不连续的壁，与卵细胞和中央细胞之“间隙”无直接联系，另一助细胞合点端仅有质膜，并通过质膜间断处与卵细胞和中央细胞之间的“间隙”相通。中央细胞珠孔端和合点端有壁内突，极核或次生核及大部分细胞质靠近卵器，内有大量淀粉粒。开花后２１ｈ，双受精已完成。合子合点端壁由不连续到连续，细胞器丰富。退化助细胞合点端壁不连续，与合子间的壁某些部位很薄或间断，宿存助细胞合点端壁以及与合子间的壁亦不连续，丝状器仍发达。受精极核或次生核已分裂形成２～４个胚乳游离核，周围细胞质内仍有大量淀粉粒。

After 1￣ 8 h of anthesis, the egg cell has no wall at its chalazal end and a space is present between the plasma membranes of the egg cell and central cell which are discontinuous. The cytoplasm of the egg cell is mainly located at its chalazal portion in which the organelles are inactive. One synergid bears no complete wall at its chalazal end. The other has no wall and the plasma membrane is also discontinuous at its chalazal end which can connect with the 'space' between the egg cell and central cell. Wall ingrowths appear at the micropylar and chalazal ends of the central cell. The polar nuclei or secondary nucleus and the surrounding cytoplasm in which many large starch grains are found are near the egg apparatus. At 21 h after anthesis, double fertilization is finished. The chalazal end wall of the zygote which contains abundant organelles changes from discontinuous to complete. The degenerated synergid has a discontinuous wall at itschalazal end and a thin or a discontinuous wall adjacent to the zygote in some places. The persistent Synergid also has a discontinuous wall at its chalazal end and adjacent to the zygote, its filiform apparatus is still developed. 2￣ 4 endosperm nuclei are formed and in their surroundingcytoplasm many large starch grains are still observed.