Temperature-dependent ultrastructural changes in the cone interphotoreceptor matrix.
OBJECTIVE
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.
Department of Ophthalmology, Akita University Faculty of Medicine, Akita, Japan. mako@med.akita-u.ac.jp
Makoto
M
Ishikawa
Toshiyuki
T
Fujiwara
Takeshi
T
Yoshitomi
D000818:Animals; D002417:Cattle; D005109:Extracellular Matrix / Q000378:metabolism / Q000648:ultrastructure*; D019887:Peanut Agglutinin / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism / Q000648:ultrastructure*; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000648:ultrastructure*; D013696:Temperature; D000267:Tissue Adhesions
D019887:Peanut Agglutinin