[Electron microscopic research on the capillary permeability of the primary portal plexus in rats in the prenatal period].
Permeability of portal capillaries to intravascularly injected ionic lanthanum, ferritin and horse-radish peroxidase has been examined in rats on the 18th fetal day, and on days 1 and 9 of postnatal life. For several minutes, tracer molecules pass through the capillary wall and reach the median eminence. In the case of immature capillaries, the materials pass freely through the endothelial cells, and to a lesser extent are transferred via occasional plasmalemmal vesicles and fenestrae. As the maturation of capillaries proceeds their permeability via plasmalemmal vesicles and fenestrae increases considerably due to a gradual rise in the number of these structures. The plasmalemma of differentiated endothelial cells becomes impermeable to all the tracers. Only ionic lanthanum appears to penetrate through transendothelial channels and intercellular junctions between adjacent endothelial cells.
D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects; D004727:Endothelium / Q000187:drug effects / Q000648:ultrastructure; D005260:Female; D005293:Ferritins / Q000494:pharmacology; D005865:Gestational Age; D006735:Horseradish Peroxidase / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D008854:Microscopy, Electron; D011168:Portal System / Q000187:drug effects / Q000196:embryology / Q000648:ultrastructure*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
C016534:lanthanide nitrate; D007811:Lanthanum; D005293:Ferritins; D006735:Horseradish Peroxidase
Elektronno-mikroskopicheskoe issledovanie pronitsaemosti kapilliarov pervichnogo portal'nogo spleteniia u krys v perinatal'nom periode.