Temperature-dependent ultrastructural changes in the cone interphotoreceptor matrix

Abstract

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 degrees C, 37 degrees C, or 40 degrees 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 degrees C. It became more dispersed and composed of granular elements at 37 degrees C. At 40 degrees 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.