刘氏蝎蛉卵巢管结构和卵子发生(英文)

Structure of ovarioles and oogenesis in Panorpa liui Hua(Mecoptera:Panorpidae)

卵巢管结构及卵子发生过程在探讨昆虫系统发育关系中有重要意义,深入研究长翅目昆虫卵巢管结构及卵子发生可为确定其在全变态类昆虫中的系统发育地位提供依据。本文利用光学显微镜和扫描、透射电子显微镜技术研究了刘氏蝎蛉Panorpa liui Hua卵巢管超微结构及卵子发生过程。结果表明:蝎蛉卵巢由12根多滋式卵巢小管组成,每个卵巢小管分为端丝、生殖区和生长区。根据滋养细胞、卵母细胞及滤泡细胞的变化,卵子发生过程可分为5个阶段:卵黄发生前早期、卵黄发生前中期、卵黄发生前后期、卵黄发生期及卵壳形成期。在卵黄发生期,滋养细胞为卵母细胞提供养分后逐渐消亡,而此时的卵母细胞可通过滤泡之间的细胞间隙从血淋巴中获取营养。在卵壳形成期间,3种不同类型的滤泡细胞参与形成不同区域的卵壳,从而形成不同花饰的卵壳表面。据此推测,与其他目的滋养细胞数目相比,每个卵室中2次有丝分裂形成3个滋养细胞可能是比较原始的特征,表明长翅目昆虫可能是全变态类群中近基部的分支。

The ovariole structure and oogenesis have significance in exploring the phylogenetic relationships in insects.Detailed investigation on ovariole structure and oogenesis of Panorpidae could provide the evidence of phylogenetic position of Mecoptera in Holometabola.The ovariole structure and oogenesis of the scorpionfly Panorpa liui Hua were investigated using light microscopy and scanning and transmission electron microscopy.The results showed that each of the two ovaries consists of 12 polytrophic ovarioles,which can be differentiated into the terminal filament,a germarium,a vitellarium and a pedicel.Based on the variations of the nurse cells,oocyte,and follicle cells,the process of oogenesis can be divided into five stages：early,middle and late previtellogenesis,vitellogenesis and choriogenesis.During the vitellogenesis,the nurse cells provided the nutrition for the oocyte and then degenerated gradually.When the nurse cells disappear completely,the nutrition of the oocyte might be supported by the hemolymph through the interspace between follicle cells.Three types of follicle cells surrounding the oocyte are responsible for the eggshell formation in different regions,resulting in the distinct meshwork on the eggshell.Through comparison with the nurse cell number in other orders,we speculate that three nurse cells in each egg chamber might be a plesiomorphic character,suggesting that Mecoptera represent a basal lineage in Holometabola.