ISSN:
0002-9106
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Previous experiments have suggested that the guinea pig chorio-allantoic placenta is a barrier to the maternal-fetal passage of proteins. The means by which the placenta exercises this barrier function were investigated by electron microscopy after injection of peroxidase, ferritin, and Thorotrast. Uptake of protein was by coated vesicles which formed at the trophoblast surface, pinched off, and migrated deeper into the cytoplasm. Some vesicles emptied into multivesicular bodies; others migrated across the trophoblast, emptying their content into the underlying compartment. Peroxidase and ferritin were observed in basement membranes within 10-20 minutes after injection. At longer intervals, the proteins were increasingly difficult to demonstrate in basement membranes, although increased amounts were present in the trophoblast. Neither the basement membranes nor the fetal capillary endothelium constituted an effective barrier to proteins which crossed the trophoblast. The results suggest that the trophoblast is the major barrier to maternal-fetal protein transfer across the labyrinth. The trophoblast appears to exercise this barrier function by (a) having a low rate of protein absorption and (b) having multivesicular bodies and lysosomes which sequester and possibly degrade absorbed proteins. However, the trophoblast is not a complete barrier to the passage of these exogenous proteins which may indicate a normal, albeit minor, pathway of maternal-fetal protein transport.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aja.1001300404
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