| The median eminence in normal, ovariectomized, and ovariectomized-estradiol-treated hamsters: an ultrastructural study. | |
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MedLine Citation:
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PMID: 7193969 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In an effort to define more clearly the effect various plasma concentrations of estrogen have on the morphology and function of tanycytes, the present investigation examined the median eminence (ME) of normally cycling, ovariectomized, and ovariectomized-estradiol-treated hamsters. In normally-cycling animals, when endogenous estrogen was at its highest level (day 4 or proestrus), numerous microappendages arose from the luminal surfaces of tanycytes located in the ventrolateral region of the ME. Large blebs (1.0-5.0-micrometers diameter), miniblebs (1.0-micrometer diameter), and microvilli dominated the surfaces of these cells. Large blebs appeared to have been formed by the coalescence of several miniblebs and were composed of cytoplasmic ground substance devoid of organelles. The peduncular shape of many of these blebs suggested their involvement in an apocrinelike secretion by the tanycyte. When endogenous estrogen levels were low (day 1 of the estrous cycle), the tanycytes of normally cycling hamsters possessed slightly fewer microappendages. Following ovariectomy, large blebs were nearly absent from the luminal surfaces of tanycytes, and the number of miniblebs and microvilli were also greatly reduced. Subcutaneous injections of 17-beta estradiol benzoate restored the large blebs to the tanycyte surface. The number and variety of tanycytic microappendages in these animals resembled those in normally cycling hamsters on day 4 of the estrous cycle. The present study demonstrates that tanycytes of the hamster ME are sensitive to estrogen and vary in their morphology in relation to the animal's reproductive status. These changes in tanycyte morphology can be correlated directly to functions of absorption (microvilli) and secretion (blebs). The sensitivity of tanycytes to estrogen suggests that these cells may also play a role in the hypophyseal-ovarian feedback mechanism. |
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Authors:
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R E Merchant; J R Dollar |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The American journal of anatomy Volume: 160 ISSN: 0002-9106 ISO Abbreviation: Am. J. Anat. Publication Date: 1981 Jan |
Date Detail:
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Created Date: 1981-05-21 Completed Date: 1981-05-21 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0376312 Medline TA: Am J Anat Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1-16 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Castration Cricetinae Estradiol / pharmacology* Estrus Female Hypothalamo-Hypophyseal System / ultrastructure* Median Eminence / drug effects, ultrastructure* Microscopy, Electron, Scanning Microvilli / drug effects, ultrastructure Ovary / physiology* Pregnancy |
| Chemical | |
Reg. No./Substance:
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50-28-2/Estradiol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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