凡纳滨对虾卵子发生的超微结构

利用透射电镜研究凡纳滨对虾卵子发生过程中细胞内部结构的变化。结果显示，卵原细胞结构简单，代谢水平低，核孔稀少，通过核周池来完成核、质之间的物质交换。卵黄发生前晚期和卵黄发生初期的卵母细胞变化显著：核膜凹凸不平，核仁数量多，核孔密集，大量核仁外排物经核孔输送到卵质中；卵质中胞器极为丰富和发达，代谢活性极强。卵黄发生旺盛期是卵黄大量形成的阶段，卵质边缘还呈辐射状排列了一圈椭圆形皮质棒，细胞出现微吞饮活动并形成卵黄膜。卵黄发生晚期卵质中充满了粗大的卵黄粒和脂滴，胞器锐减。另外，探讨了卵细胞内部结构的变化和卯黄形成的关系以及皮质棒的来源与功能。

Ultrastructure on oogenesis of Litopenaeus vannamei

The changes of the structure in oocytes during the oogenesis of Litopenaeus vannamei were studied with transmission electron microscope. The results showed that the structure was simpler and the active metabolism is lower in oogonium. The particles from the nucleus mainly passed through the perinuclear cisternae into the cytoplasm because of fewer nuclearpores. The marked changes occurred in the latter previtellogenic oocytes and the primary vitellogenic oocytes. The nuclear changes consisted of the concavo-convex nuclear membrane, many more nucleoli, numerous nuclearpores and a large amount of nucleolns granular materials penetrating nuclear membrane into cytoplasm. There were various well-developed organelles in the cytoplasm which exhibited higher synthetic activity. The yolk granules formed mainly in active vitellogenesis. At this stage, a lap spherical cortical rods appeared radializedly at the edge of the cytoplasm. Meanwhile active microphagocytosis could be seen along the ooplasma membrane while the vitellin membrane formed on the surface of vitellogenic oocytes. The mature oocytes were fill of big yolk granules and lipid droplets and the number of organelles reduced quickly. The relation between the changes of the structure in oocytes and the vitellogenesis was discussed. The origin and function of the cortical rods were also discussed.