Nuclear secretory particles associated with the calyx cells of the ichneumonid parasitoid Campoletis sonorensis (Cameron)

The present study is an ultrastructural investigation of the calyx region of the ichneumonid endoparasitoid Campoletis sonorensis. It appears that synthesis of electrondense secretory particles occurs within nuclei of calyx cells. The particles consist of an ovocylindrical electron-dense inner core and a surrounding unit membrane. After their formation the particles pass from the nucleus by budding through both membranes of the nuclear envelope. The particles, along with fully developed parasitoid eggs concentrate within the lateral oviduct lumen. Feulgen histochemical studies suggest the presence of DNA within the calyx fluid. The possible function of the particles is discussed.