›› 2010, Vol. 53 ›› Issue (11): 1220-1226.

• RESEARCH PAPERS • Previous Articles     Next Articles

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

MA Na, HUA Bao-Zhen   

  • Online:2011-01-17 Published:2010-11-20

Abstract:

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.

Key words: Mecoptera, Panorpidae, ovary, histology, ultrastructure