Document Detail

Star volume estimates of the intervillous clefts in the human placenta: how changes in umbilical arterial pressure might influence the maternal placental circulation.
MedLine Citation:
PMID:  8089439     Owner:  NLM     Status:  MEDLINE    
The study estimated the mean volume of the clefts between adjacent villi in the normal term human placenta, and the effect on this of increasing the fetal perfusion pressure, using a new stereological tool called the 'star volume estimator'. This enables the measurement of irregular and complex structures, including both particles and cavities, in a mathematically defined and unbiased manner. To achieve this, a total of ten term placentae delivered by caesarean section were obtained. Four fetal arteries supplying opposite quadrants of the placental disc were perfusion-fixed under standard pressures of 40, 60, 80 and 100 mmHg respectively. Stereological estimates relating to the star volume of the clefts between the villi, and to the volume density of the intervillous space were obtained. There was a significant rise in the star volume of the intervillous clefts from 26.8 x 10(4) m3 at 40 mm Hg to 75.1 x 10(4) m3 at 100 mmHg (F = 75, df = 1.38, P < 0.05). The volume density of the intervillous space remained unchanged, thus obviating the possibility of fluid leakage into the intervillous space accounting for this change. It is concluded that the fetal vasculature provides hydraulic support to the villous tree, and that changes in the umbilical perfusion pressure can therefore alter the disposition of the villi within the intervillous space. As fetal blood pressure rises, for example during acute hypoxic episodes, the villi will move apart. The enlargement of the clefts between adjacent villi will have a secondary effect upon the maternal circulation, promoting more even perfusion of the intervillous space at higher overall flow rates.(ABSTRACT TRUNCATED AT 250 WORDS)
A L Karimu; G J Burton
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of developmental physiology     Volume:  19     ISSN:  0141-9846     ISO Abbreviation:  J. Dev. Physiol.     Publication Date:  1993 Mar 
Date Detail:
Created Date:  1994-10-14     Completed Date:  1994-10-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7910737     Medline TA:  J Dev Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  137-42     Citation Subset:  IM    
Department of Anatomy, University of Cambridge, UK.
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MeSH Terms
Blood Pressure*
Chorionic Villi / anatomy & histology,  blood supply*
Extraembryonic Membranes / anatomy & histology,  blood supply
Placenta / anatomy & histology,  blood supply*
Regional Blood Flow
Umbilical Arteries / physiology

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