| Review: Marsupials: placental mammals with a difference. | |
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MedLine Citation:
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PMID: 20079531 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The placenta is the most varied organ within the Mammalia. There are many similarities, as well as some differences, between the marsupial embryo and those of eutherian mammals. The most striking difference is the lack of the inner cell mass in the blastocyst which consists solely of a single layer of trophoblast cells. The trophoblast expands and eventually becomes part of the definitive chorio-vitelline placenta. The degree of functional differentiation between the vascular and non-vascular parts of the yolk sac placenta differs between species in the relative surface area that is attached to the endometrium, in trophoblast thickness, in yolk sac fusion with the luminal epithelium and most markedly in the degree of invasiveness. In marsupials, placental physiology has been best studied in the tammar wallaby. Despite the lack of invasion in the tammar, there is nevertheless maternal recognition of pregnancy in response to trophoblast formation. Contrary to popular opinion, the tammar placenta also elaborates hormones: at term it secretes prostaglandin F2alpha and accumulates cortisol, and it expresses genes for hormones such as growth hormone, IGF2 and relaxin. As in eutherian mammals, genomic imprinting is important for placental function. Despite the relatively short period of placentation, it is clear that the trophoblast and the placenta it forms are as important for successful pregnancy in marsupial as in eutherian mammals. Marsupials are certainly placental mammals. However marsupials have an additional trick in their pouches, with the physiologically sophisticated and extended lactation that has allowed them to exchange the umbilical cord for the teat. |
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Authors:
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M B Renfree |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Review Date: 2010-01-15 |
Journal Detail:
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Title: Placenta Volume: 31 Suppl ISSN: 1532-3102 ISO Abbreviation: Placenta Publication Date: 2010 Mar |
Date Detail:
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Created Date: 2010-02-22 Completed Date: 2010-05-13 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8006349 Medline TA: Placenta Country: England |
Other Details:
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Languages: eng Pagination: S21-6 Citation Subset: IM |
Copyright Information:
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Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved. |
Affiliation:
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Department of Zoology, The University of Melbourne, Victoria 3010, Australia. m.renfree@unimelb.edu.au |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Female Genomic Imprinting / physiology Marsupialia / physiology* Maternal-Fetal Exchange Placenta / physiology* Placentation / physiology* Pregnancy |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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