zonula occludens(redirected from impermeable junction)
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tight junctions formed by the fusion of integral proteins of the lateral cell membranes of adjacent epithelial cells, limiting transepithelial permeability.
zonula(zon'yu-la) [L. zonula, little girdle]
A small zone. Synonym: zonule
The portion of the junctional complex between columnar epithelial cells below the zonula occludens where there is an intercellular space of about 200 A.U. and the cellular membranes are supported by filamentous material.