Follicular sheath (ovarian sheath) structure in virginoparae of the vetch aphid,Megoura viciae Buckton (Homoptera : Aphididae) |
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| Institution: | 1. School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K.;1. Department of Environmental Biology, University of Manchester, Manchester, M13 9PL, U.K.;1. UMR Physiologie de la Reproduction et des Comportements, INRA, CNRS, IFCE, Université de Tours, 37380 Nouzilly, France;2. Departamento de Producción Animal y Cienca de los Alimentos, Instituto Universitario de Investigación en Ciencias Ambientales (IUCA), Universidad de Zaragoza, Miguel Servet, 177, Zaragoza 50013, Spain;3. Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Torreón, Coahuila, Mexico;1. Nucleus of Biotechnology Applied to Ovarian Follicle Development, Federal University of São Francisco Valley, Petrolina, PE 56300-990, Brazil;2. Health Center Science, State University of Ceará, 60714-903 Fortaleza, CE, Brazil;1. São Paulo State University (Unesp), Department of Pharmacology, Institute of Biosciences, Botucatu, SP, Brazil;2. University of Western São Paulo (Unoeste), Presidente Prudente, SP, Brazil;1. Large Animal Health Laboratory, Federal University of Uberlândia, Uberlândia-Minas Gerais, 38400-902, Brazil;2. Laboratory of Biology of Reproduction, Instituto de Ciências Biomédicas, Federal University of Uberlândia, Uberlândia-Minas Gerais, 38400-902, Brazil;3. Laboratory of Animal Pathology, Department of Veterinary Preventive Medicine, Universidade Estadual de Londrina, Paraná, 86057-970, Brazil |
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| Abstract: | The anatomy of the follicular (ovarian) sheath surrounding the embryos in the virginoparae of the vetch aphid, Megoura viciae Buckton (Homoptera : Aphididae) is described. Enlarging oocytes released from the germaria are enveloped in a monolayer of cells derived from the prefollicular tissue, which is continuous with the sheat surrounding the germarium. Each embryo is compartmentalized. Initially, the sheath cells are cuboidal, but as division and elongation of the oocytes ensue, they become progressively stretched. Sheath cells surrounding large embryos show some variability in structure. In some areas, they are little more than a pair of membranes separated by a trace of cytoplasm. In other areas, they are thicker and have a structure that indicates a role in the uptake of materials. In these areas, the cells are often invaginated, with particulate and flocculent material present in the folds, and numerous organelles in the cytoplasm. Microvilli occur around some of the sheath cells and microtubule bundles are present in cells where the sheath is folded to form areas of contact between cells. A very thin acellular tunica propria is present to the exterior of the follicular sheath cells. Two acellular “membranes” present between the sheath cells and embryonic epidermal cells may have a role in the regulation of materials transfer. The structure of the epidermal cells of the embryos indicates role in the uptake of materials. |
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