Morphological features of the spermathecae of virgin and inseminated Aedes aegypti females

In general, the insect spermatheca is subdivided into the reservoir, duct and gland, which are responsible to store, to transport and to maintain the sperm viability until egg fertilization, respectively. So, spermatheca promotes the independence and reproductive success of females. In the present work, the fine structure of virgin and inseminated spermathecae of the yellow fever mosquito Aedes aegypti females is investigated through optical (including hystochemistry) and scanning and transmission electron microscopies. In A. aegypti there are one large and two small spermathecae. In spite of this size difference, virgin and inseminated spermathecae have the same overall organization. They are covered internally by a thick cuticle and externally by a single thin layer of epithelial cells that are poor of organelles. Reservoir epithelium is thinner then duct epithelium and at reservoir external surface, cell nuclei are seen as protuberances. Gland cells have a round well-developed nucleus and their cytoplasm is rich in mitochondria associated with microvilli. These microvilli are close to cell ductule that trespass reservoir cuticle and open into reservoir lumen, where bundles of spermatozoa are observed. These cells apex and ductule lumens are PAS-positive, suggesting that they produce and secrete polysaccharides, probably related to the maintenance of spermatozoa even before copulation. The values of reservoir diameters and cuticle are not different, considering virgin and inseminated females. The better understanding aspects of the spermatheca in details provide new insights into the reproductive strategies of mosquitoes and potential new targets for vector population control through intervention in their reproductive output.