Heteropteran ovaries: variations on the theme.

Ovaries of heteropterans consist of telotrophic meroistic ovarioles that are composed of apically located tropharium and basal vitellarium, containing developing oocytes. The tropharium (trophic chamber) houses trophocytes (nurse cells) that are connected with the centrally located trophic core. The organization of the heteropteran tropharia is highly variable and differs in representatives of primitive versus advanced families. The differences concern the mitotic activity of the apical nurse cells, organization of the trophocytes (individual cells or "syncytial lobes"), their connection with the trophic core and the development of F-actin meshwork around the trophic core. In members of primitive taxa of the Heteroptera, tropharia are composed of individual, usually mononucleate trophocytes. On the contrary, tropharia in advanced heteropterans are built of large "cytoplasmic lobes" that contain several trophocyte nuclei. Mitotic divisions of the trophocytes in the apical part of the trophic chamber are observed in most bugs (except Dipsocoridae, Miridae and Cimicidae). Tropharia of Miridae represent an entirely different organization (they are built of one type of highly polyploid trophocytes). Anagenesis of heteropteran trophic chamber is discussed in the context of presented data.