| The flea ovary: ultrastructure and analysis of cell clusters. | |
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MedLine Citation:
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PMID: 18620245 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Panoistic ovarioles are found in the order of fleas (Siphonaptera). Only in some species of the Hystrichopsylloidea do polytrophic meroistic ovaries occur. No stem cells and no dividing cystocytes are found in female imagines of Hystrichopsylla talpae. However, each germ cell cluster consists of 32 cells which are generated by five mitotic cycles during the pupal stage. One of the cells containing five intercellular bridges becomes the oocyte, the others serve as nurse cells. Thus, germ cell cluster formation follows the 2(n)-rule. However, no polyfusome is found and nurse cells do not form a rosette. Furthermore, nurse cells remain small and show the same ultrastructural characters as the oocytes, which became distinguishable from nurse cells only by their enhanced growth during pre-vitellogenesis. The first phase of pre-vitellogenesis is dominated by the production of an unknown cytoplasmatic component, consisting of spherical particles, clearly distinguishable from ribosomes by diameter and contrast. The next phase is characterized by a tremendous increase in the production of ribosomes. During this second phase another cytoplasmic component consisting of ball-like structures becomes prominent. During pre-vitellogenesis, germ cell nuclei undergo a pronounced structural change in which, finally, numerous extranucleolar particles predominate. Thus, H. talpae has a polytrophic meroistic ovary, but its oocyte genomes behave panoistically. |
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Authors:
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J B??ning; S Sohst |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Tissue & cell Volume: 20 ISSN: 0040-8166 ISO Abbreviation: Tissue Cell Publication Date: 1988 |
Date Detail:
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Created Date: 2008-07-14 Completed Date: 2009-12-16 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0214745 Medline TA: Tissue Cell Country: Scotland |
Other Details:
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Languages: eng Pagination: 783-95 Citation Subset: - |
Affiliation:
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Institute of Zoology I, University of Erlangen-N??rnberg, Erlangen, F.R.G. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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