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1

Organization of the egg chambers in Hydradephaga (Insecta, Coleoptera-Adephaga) and its phylogenetic significance

100%
Jaglarz M. K., Bilinski S. M.
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EN
The structure of the ovaries in three representatives of Hydradephaga (Haliplus flavicollis, Gyrinus natator and Orectochilus villosus) and one of Geadephaga (Carabus variolosus) was studied. In all the investigated species the ovarioles are of the meroistic polytrophic type. Within ovarioles several egg chambers occur, clearly separated into two compartments: one occupied by nurse cells and the other by an oocyte. The analysis of serial semithin sections revealed that the clusters of the germ cells are branched and that there are always 7 nurse cells in the egg chambers in the examined Hydradephaga. In contrast, the number of nurse cells in Carabus variolosus egg chambers is variable and much greater (around 60). In addition, in the last species a few trophocytes were found containing 2 nuclei. In view of the results obtained the possible phylogenetic implications are discussed. A tentative hypothesis is proposed that a small and constant number of the nurse cells might be a plesiomorphic condition for the suborder Adephaga.
2

Diversification of follicular cells in the ovaries of the horse fly Haematopota italica (Diptera: Tabanidae). similarities and differences with the Drosophila Model System

81%
Jaglarz M. K., Jablonska A., Kisiel E., Bilinski S. M.
Folia Biologica
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2009
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vol. 57
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issue 1-2
1-12
EN
In insect ovaries, germ line cells are surrounded by somatic cells that initially form a uniform follicular epithelium. The subsequent diversification of the follicular cells into several subpopulations enables specification of distinct structures in different regions of complex eggshells. It also influences the patterning of the future embryo. These processes have been extensively studied at both the cellular and molecular levels using the Drosophila ovary as a model system. It is not clear however, to what extent the Drosophila model of the follicular epithelium patterning is universal for the entire Diptera group. Here, we analyze the diversification of the follicular cells in a distant Drosophila relative, the horse fly, Haematopota italica. We found that in this species, there are 6 recognizably different follicular cell subpopulations within the previtellogenic ovarian follicles. Ultrastructural analysis of the follicular epithelium revealed two morphologically distinct clusters of follicular cells residing at the anterior and posterior poles of the follicles. Each cluster consists of 2-3 polar cells located centrally and surrounded by several outer cells called border cells (at the anterior pole) or border-like cells (at the posterior pole). During previtellogenesis, the clusters lose the initial symmetry as their cells differentiate and develop conspicuous cytoplasmic projections comprising cytoskeletal elements. Ultimately, the follicular cells of the anterior and posterior clusters become morphologically different and, as we suggest, participate in different processes during oogenesis and formation of the and, eggshell in H. italica.
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