Abeer S. Yamany
Age determination technique of mosquitoes was described for An. pharoensis Theobald from Egypt by observing the ovarian changes before and through the gonotrophic cycles. During this ovarian development cycle, seven growing stages of the oocyte were observed in the adult stage. Two distinct periods of egg follicle growth, the previtellogenesis and vitellogenesis, were seen first. The gradual increase in the oocyte size during these phases was attributed to yolk deposition. During vitellogenesis, the oocyte and nurse cell nucleus were similar in size (stage I). Then, the oocyte enlarged and occupied one third of the egg follicle, while the nurse cell (NC) occupied the remaining two thirds. At this phase, the yolk granules (stage III) enlarged, occupying about half of the egg follicle, while the NC contained the other half (stage IV). An increase and accumulation of yolk granules led to the filling of about three fourths of the egg bulk and made the oocyte nucleus hardly visible during stage V. The oocyte undergone a remarkable growth, occupying nine tenth of the length of the follicle in stage VI. Stage VII corresponded to a mature cigar shaped egg and contained two kinds of yolk globules: a large one and a small one. The oocyte and the NC at all stages were surrounded by a single layer of epithelial cells which increased in number, forming the vitelline membrane and the chorion. The mitochondria in the NC, oocyte, and follicular epithelium appeared in light microscopy as granules of different sizes. The Golgi apparatus appeared in different sizes and shapes, since in the early stages of development, it is restricted to the perinuclear zone. When the development proceeded, it enlarged in size, spread over the whole cytoplasm, and participated in the formation of the yolk