Maturation of Oocytes and Vitellogenesis during the Development of Ovary in the House Cricket Gryllodes sigillatus (Walker) (Orthoptera:Gryllidae)

In G. sigillatus, the ovaries are panoistic type in which the ovarioles exhibit a progressive increase in dimension as the development proceeds. The yolk deposition was found to commence on the 4th day of adult emergence in the basal oocyte which attained a fully mature stage on day 8. During this process, considerable changes were observed in both the oocytes and the follicular cells from the second day of female adult emergence. In the earlier adult instars, yolk spheres appeared in the cortical region of the ooplasm and large yolk spheres in the central region during vitellogenic phase. At the time of vitellogenesis, the follicular epithelial cells of the basal oocytes were tall and columnar with intercellular spaces. As the vitellogenesis progressed, the cells became cuboidal and the oocytes developed vitelline membrane and chorion. The present study also reveals that vitellogenesis in Gryllodes sigillatus occurs both in the penultimate and basal oocytes simultaneously.