Purpose: To determine the temperature-dependent ultrastructural changes of the cone matrix sheath, a possible critical factor in the adhesive strength binding photoreceptors and pigment epithelial cells. Methods: Aqueous-insoluble interphotoreceptor matrix (IPM) was extracted by soaking fresh bovine retinas in acidic HEPES-buffered solution followed by treatment with 1% Triton X-100 to remove cone membrane fragments. The IPM preparations were then incubated in the same buffer solution at either 34°C, 37°C, or 40°C for 60 min. After labeling with peanut agglutinin, the samples were prepared for electron microscopy. Results: The cone matrix sheath, specifically stained with peanut agglutinin, was markedly condensed at 34°C. It became more dispersed and composed of granular elements at 37°C. At 40°C, the matrix appeared as a network of fine filamentous structures. Conclusions: These findings suggest changing temperatures can alter the molecular organization of the IPM and thus influence its retinal adhesion.
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