tight junction

(redirected from Zonulae occludentes)
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zo·nu·la oc·clu·'dens

tight junctions formed by the fusion of integral proteins of the lateral cell membranes of adjacent epithelial cells, limiting transepithelial permeability.

tight junc·tion

(tīt jŭngk'shŭn)
An intercellular junction between epithelial cells in which the outer leaflets of lateral cell membranes fuse to form a variable number of parallel interweaving strands that greatly reduce transepithelial permeability to macromolecules, solutes, and water through the paracellular route.

tight junction 

Refers to cells in which their membranes are fused rather than separated by a small extracellular space. The movement of substances through that space is restricted. Syn. zonulae occludentes. See blood-brain barrier.
References in periodicals archive ?
The zonulae occludentes were deep (1.4 [plus or minus] 0.7 [micro]m, n = 19 replicas) and composed of 21.8([plus or minus]4.5) fibrils (Fig.
In electron micrographs, CAH was localized in the intercellular space between columnar cells but excluded from the zonulae occludentes (Fig.
The zonulae occludentes of columnar cells consisted of about 22 strands, suggesting that the epithelium is electrically tight and imparts a high transepithelial resistance (Claude and Goodenough, 1973; Claude, 1978).