Document Detail

Placentation in the degu (Octodon degus): analogies with extrasubplacental trophoblast and human extravillous trophoblast.
MedLine Citation:
PMID:  16448832     Owner:  NLM     Status:  MEDLINE    
This study examined the placentation in the degu, the origin of the extrasubplacental trophoblast (EST) (extravillous trophoblast in human), and the activity of Na+/K+ ATPase in the placental barrier during different gestational ages, as part of a wider effort to understand the reproductive biology of this species. Fifteen degus at the first stage of gestation, midgestation and at term of pregnancy were studied. At day 27 of gestation, the subplacenta is formed under the wall of the central excavation. Simultaneously, the outermost trophoblast of the ectoplacental cone differentiated into secondary trophoblast giant cells that lie on the outside of the placenta, forming an interface with the maternal cells in the decidua. These giant cells immunostained positive for cytokeratin (CK) and placental lactogen (hPL) until term. During this period, the EST merged from the subplacenta to the decidua and immunostained negative for CK, but at term, immunostained for CK and hPL in the maternal vessels. The vascular mesenchyme of the central excavation invaded the chorioallantoic placenta during this period, forming two fetal lobules of labyrinthine-fine syncytium, the zone of the placental barrier. The activity of Na+/K+ ATPase in the placental barrier was constant during the gestational period. The residual syncytium at the periphery of the placental disc and between the lobules was not invaded by fetal mesenchyme and formed the marginal and interlobular labyrinthine syncytium that immunostained first for CK, and later for hPL, as in the labyrinthine fine syncytium. The presence of intracytoplasmic electron-dense material in the interlobular labyrinthine syncytium suggested a secretory process in these cells that are bathed in maternal blood. Placentas obtained from vaginal births presented a large, single lobe, absence of the subplacenta, and a reduced interlobular labyrinthine syncytium. At day 27, the inverted visceral yolk sac is observed and its columnar epithelium immunostained for CK and hPL. This suggests that the yolk sac is an early secretory organ. The epithelium of the parietal yolk sac covers the placenta. The origin of the EST in the degu placenta and its migration to maternal vessels allows us to present this animal model for the study of pregnancy pathologies related to alterations in the migration of the extravillous trophoblast.
Cleofina Bosco; Chosica Buffet; M Angélica Bello; Ramón Rodrigo; Michelle Gutierrez; Gernika García
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-01-31
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  146     ISSN:  1095-6433     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-03-09     Completed Date:  2007-06-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  475-85     Citation Subset:  IM    
Programas de Anatomía y Biología del Desarrollo, ICBM, Facultad de Medicina, Universidad de Chile, Chile.
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MeSH Terms
Embryo Implantation
Gestational Age
Octodon / physiology*
Parturition / physiology
Placenta / cytology*
Placentation / physiology*
Yolk Sac

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