Oogenesis inKalotermes flavicollis(Fabr.) (Isoptera: Kalotermitidae). I. Differentiation and maturation of oocytes in female supplementary reproductives
作者:
Gilberto Grandi,
Roberta Barbieri,
Giuseppe Colombo,
期刊:
Bolletino di zoologia
(Taylor Available online 1988)
卷期:
Volume 55,
issue 1-4
页码: 103-122
ISSN:0373-4137
年代: 1988
DOI:10.1080/11250008809386606
出版商: Taylor & Francis Group
关键词: Ovary;Previtellogenic growth;Vitellogenic growth;Ultrastructure;Kalotermes flavicollis
数据来源: Taylor
摘要:
The ovary of female supplementary reproductives is constituted by panoistic‐type ovarioles containing a linear array of germ cells in successive stages of differentiation. In the distal region of the germarium, germ cells cannot be morphologically and ultrastructu‐rally discriminated from somatic cells. In the middle and proximal region of the germarium, oogonia at two developmental stages have been identified. The oocytes at the beginning of meiosis are characterized by nuclear vacuoles and by a polar localization of cell organelles, in addition to synaptonemal complexes. The post‐pachytcne oocytes are partially isolated by prefollicular cell extensions and show annulate lamellae and Balbiani bodies. During previtellogenesis, the oolemma forms microvilli, with coated pits and vesicles, about 60 nm in diameter, at their bases. At the onset of vitellogenesis, coated pits and vesicles about 120 nm in diameter and early yolk globules appear in the cortical ooplasm. At a later stage, wide spaces filled with flocculent material are formed between the oocyte and follicular cells, and coated pits and vesicles about 180 nm in diameter are found in the cortical ooplasm. In late vitellogenesis, the endocytotic activity decreases, and large yolk globules and lipid droplets fill the whole ooplasm. The ultrastructural features during differentiation provide evidence of organelle renewal before vitellogenesis and then exogenous yolk synthesis.
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