LACK OF CORRELATION BETWEEN TIGHT JUNCTION MORPHOLOGY AND PERMEABILITY PROPERTIES IN DEVELOPING CHOROID-PLEXUS

Abstract

ELECTRON microscopical investigations of tight junctions (zonulae occludentes) using marker substances, have indicated that in some tissues these junctions may represent an extracellular pathway for transepithelial movement of certain small solutes1 and also restrict the movement of larger solutes2. The electrical resistance across some epithelial tissues has been used as a measure of the degree of permeability of the tight junctions to ions3, and it was suggested that junctions that are "leaky" to ions are also leaky to small non-electrolytes. Examination of tight junctions with the freeze-fracture technique has revealed the presence of a network of intramembranous fibrils4 or strands5,6. S..