The Reticulitermes lucifugus ovary consists of about 40 panoistic ovarioles. A transverse septum between the terminaI filament and germarium is absent, where two successive developmental stages of oogonia afe recognizable. Early meiotic oocytes with synaptonemal complexes and nuclear vacuoles characterize the prophase region. Previtellogenic oocytes fIrst show microvilli and later, in the cortical ooplasm, endocytotic vesicles about 70nm in diameter. Small yolk spheres and 120nm coated vesicles characterize early vitellogenic oocytes, while 180nm vesicles prevail in mid- and late vitellogenesis. The observations support heterosynthetic yolk production and endocytosis ofyolk precursors. Prefollicular cells surrounding oogonia and early meiotic oocytes bave a scarcely differentiated cytoplasm. Around early previtellogenic oocytes, follicular cells build a monolayered epithelium, fIrst flat then cuboidal and release a granular material on the oocyte side. They closely adhere to each other and extend microvilli interdigitating with those of the oocyte. During vitellogenesis they afe fIrst columnar then globose and show large intercellular spaces which disappear in the fmal stage of vitellogenesis when they again become fiato Follicular cells apparently regulate transfer ofmaterials for oocyte growth and after vitellogenesis synthesize egg envelope precursors. During choriogenesis they show an extended proteosynthetic apparatus whose products afe exocytosed on the egg-facing surface and, after choriogenesis, produce a fmely granular matrix covering the egg, easing oviduct transit and binding together newly laid eggs. The postovulatory follicle becomes the "corpus luteum" composed of degenerating, non-steroidogenic cells.

Oogenesis in supplementary reproductives of Reticulitermes lucifugus Rossi (Isoptera Rhinotermitidae): an ultrastructural study

GRANDI, Gilberto;CHICCA, Milvia
1999

Abstract

The Reticulitermes lucifugus ovary consists of about 40 panoistic ovarioles. A transverse septum between the terminaI filament and germarium is absent, where two successive developmental stages of oogonia afe recognizable. Early meiotic oocytes with synaptonemal complexes and nuclear vacuoles characterize the prophase region. Previtellogenic oocytes fIrst show microvilli and later, in the cortical ooplasm, endocytotic vesicles about 70nm in diameter. Small yolk spheres and 120nm coated vesicles characterize early vitellogenic oocytes, while 180nm vesicles prevail in mid- and late vitellogenesis. The observations support heterosynthetic yolk production and endocytosis ofyolk precursors. Prefollicular cells surrounding oogonia and early meiotic oocytes bave a scarcely differentiated cytoplasm. Around early previtellogenic oocytes, follicular cells build a monolayered epithelium, fIrst flat then cuboidal and release a granular material on the oocyte side. They closely adhere to each other and extend microvilli interdigitating with those of the oocyte. During vitellogenesis they afe fIrst columnar then globose and show large intercellular spaces which disappear in the fmal stage of vitellogenesis when they again become fiato Follicular cells apparently regulate transfer ofmaterials for oocyte growth and after vitellogenesis synthesize egg envelope precursors. During choriogenesis they show an extended proteosynthetic apparatus whose products afe exocytosed on the egg-facing surface and, after choriogenesis, produce a fmely granular matrix covering the egg, easing oviduct transit and binding together newly laid eggs. The postovulatory follicle becomes the "corpus luteum" composed of degenerating, non-steroidogenic cells.
1999
Grandi, Gilberto; Chicca, Milvia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1198588
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