Induced corneal swelling: an experimental model for investigation of collagen and interfibrillar substance relationships.

We report on the evolution of ultrastructural modifications in bovine and rabbit corneal sections after in vitro swelling. The number of stromal fibers decreases with time during swelling. The fact that swelling occurs more rapidly in the center of a lamellae than near the interlamellar spaces indicates that there is a heterogeneous distribution of interfibrillar matrix components and that corneal inhibition mechanisms vary according to the number of lamellaes. The appearance during swelling of periodic striations of collagen fibers and of an irregular network constituted of filaments and granules in the interfibrillar spaces suggests that corneal collagen fibers are covered by a pleated proteoglycan-glycoportein substance that is unrolled during swelling. The filaments seem to be linked to collagen via dense granules located on fibers. The distance between the granules is 643 A. A definite correspondence between the distribution of these linking granules and the periodic striations of collagen cannot be determined. Other granules of undetermined chemical nature seem to link only filaments in the interfibrillar space.