地钱卵发育超微结构和细胞化学的研究

采用电镜和细胞化学技术对地钱(Marchantia polymorpha)卵发生过程进行了研究,根据卵发生过程中细胞化学和超微结构特征可将卵发育过程分为幼卵、中期卵和成熟卵3个阶段.幼卵阶段,卵细胞、腹沟细胞及颈沟细胞间有发达的胞间连丝,但卵与腹沟细胞间的胞间连丝很快退化,幼卵细胞内具大量透明的囊泡,均匀分布于细胞质中；卵发育中期,突出特征是卵细胞质内产生嗜锇性的脂滴,位于囊泡中,与此同时,腹沟细胞退化,其细胞质内产生大型囊泡,囊泡内分泌物与卵细胞外的物质类似,呈PAS反应阳性,表明该物质应为多糖类；卵成熟时,腹沟细胞和颈沟细胞完全退化,卵细胞外包被大量粘性多糖类物质,卵细胞核表面不规则,产生明显的核外突,众多的小泡围绕着细胞核,脂滴聚集成簇,卵细胞内其他细胞器不易区分.卵发育过程中,质体不含淀粉粒,线粒体退化,高尔基体相对发达.地钱卵发育的这些特征显著区分于蕨类植物.

Ultrastructural Observation and Cytochemical Analysis of Oogenesis in Marchantia polymorpha L,

Ultrastructural and cytochemical methods were used to study egg development of the liverwort Marchantia polymorpha L. Egg development of M. polymorpha was divided into young egg,middle egg, and mature egg stages. Well-developed plasmodesmata existed be- tween the egg ,the ventral canal and the neck canal cells in the young egg stage. However,the plasmodesmata between the egg and the ventral canal cells degenerated soon after the egg was formed. At this stage, the egg cell contained numerous transparent vesicles distributed evenly in the cytoplasm. In the middle egg stage, lipid bodies were found in the vesicles of the cytoplasm. The ventral canal cell degenerated obviously. Mucilaginous materials accumulated in the vesicles and resembled that in the chamber around the egg. The mucilaginous materials showed a PAS positive reaction and were most likely polysaccharide. In the mature stage of the egg ,the ventral canal cell and the neck canal cell degenerated completely. A layer of mucilagi- nous polysaccharide encompassed the matured egg. The nucleus showed an irregular profile and apparent nuclear evaginations were produced. The nucleus appeared to show blebbing, because a numerous small vesicles occurred close the nucleus. The lipid bodies formed clus- ters around the nucleus, while other organelles were indistinguishable. During egg develop- ment,the plastids possessed no starch granules;the mitochondria degenerated,while and the Golgi bodies became more abundant. The features of the egg development of M. polymorphawere different from those in pteridophytes.