Notes on the morphology and histology of the ovarioles of Gerris lacustris (L.) (water strider) (Insecta: Hemiptera: Heteroptera: Gerridae)

Abstract

The morphology and histology of the female reproductive system of Gerris lacustris water strider (Linnaeus 1758) (Heteroptera: Gerridae) are described using both light and scanning electron microscopy (SEM). Based on histomorphology, the adult female reproductive system of G. lacustris consists of a pair of ovaries, a pair of lateral oviducts, a common oviduct. The ovaries are connected to a genital aperture by oviducts. Each adult ovary is composed of four telotrophic meroistic type ovarioles. A peritoneal sheath is a thin membranous layer surrounding the entire ovariole. The ovarioles are attached to the dorsal wall of the anterior prothorax by terminal filaments. Each ovariole is divisible into four different regions: the thread like terminal filament followed by the germarium containing nurse cells (trophocytes) and the primordial oocytes, vitellarium containing oocytes at different developmental stages and pedicel (ovariolar stalk, calyx). A long vitellarium is developed composed of a series of oocytes in their folicular sheath. The vitellarium becomes progressively large towards the distal end and the pedicel, in which the mature eggs are lodged before passing into the short lateral oviduct. It opens to the common oviduct.