Selective and reversible breakdown of the tight junctional barrier in the rabbit ciliary body induced by arachidonic acid. A tracer and freeze-fracture study.

Arachidonic acid induced a reversible breakdown of the blood-aqueous barrier in the iridial processes of the rabbit ciliary body, whereas the ciliary processes were not affected under the conditions of this study. The focal passage of horseradish peroxidase through the tight junctions was demonstrated. In freeze-fracture images, this breakdown of the barrier function was associated with focal changes: an alteration in the geometry of the tight junctional network; an increase in the number of discontinuities of the P-face ridges and particles and short bars in the E-face furrows; an increase in the density of intramembranous particles within the junctional area. The significance of the ultrastructural alterations of the tight junctions as a structural counterpart of the physiological changes is discussed.