Study on the Ultrastructural of Oogenesis of Bullacta exarata

泥螺卵子发生的超微结构研究

The ultrastructure of oogenesis of Bullacta exarata was studied with transmission electron microscope.The result showed that the oogenesis of Bullacta exarata could be divided into four stages,for example,oogonium,early vitellogenic oocyte,mid vitellogenic oocyte and end vitellogenic oocyte.Besides a large and round nucleus,oogonium mainly contains mitochondria,sacs of golgi and microvillie appears in this stage.At the early stage of vitellogenesis,the organelles are developed,and a great deal of nuages like materials appear in oocyte cytoplasm.At the mid stage of vitellogenesis,the nucleus forms pseudopodia liked extension.The organelles including mitochondria,golgi complex and endoplasmic reticulum are well developed,and lots of yolk granule and lipid droplet are formed in the cytoplasm.The exchange of material between oocytes and follicle cells is intense in this stage.At the end stage of vitellogenesis,the oocytes contain fewer numbers of the organelles.The changes of structure and significance in oocytes,and the exchange of material between oocytes and follicle cells are also discussed.

利用透射电镜观察了泥螺卵子发生过程。结果表明 ,泥螺的卵子发生可划分为卵原细胞、卵黄发生早期、卵黄发生中期及卵黄发生后期卵母细胞 4个时期。卵原细胞核大而圆 ,胞质内分布有少量的线粒体和高尔基囊泡 ,细胞表面具微绒毛。卵黄发生早期的卵母细胞 ,胞质中各类细胞器发达 ,并出现数量较多的类朦胧子。卵黄发生中期的卵母细胞胞体迅速增大 ,核伸出伪足状突起 ,卵质中各种细胞器活动活跃 ,并参与形成卵黄粒和脂滴。此期还可观察到卵母细胞与滤泡细胞间的物质交换现象。卵黄发生后期的卵母细胞体积增至最大 ,细胞器数量减少。本文就卵黄发生前后卵母细胞内部构造的变化。