Capillary lesions develop in retina rather than cerebral cortex in diabetes and experimental galactosemia

To isolate microvessels from cerebral cortex of dogs with alloxan-induced diabetes and dogs with experimental galactosemia to compare the prevalence of microvascular lesions in cerebral cortex with that in retina.

Microvessels were isolated from cerebral cortex of experimental animals using a sieving method, and compared with the retinal vasculature isolated from the same animals using the trypsin digestion method.

Dogs with diabetes or experimental galactosemia of 5 years' duration had retinopathy that was morphologically indistinguishable from that of humans with diabetes, including microaneurysms, acellular capillaries, and pericyte ghosts. These lesions never were seen in cerebral cortical vessels of the same animals. The only morphologic abnormality observed in cerebral capillaries of dogs with diabetes and dogs fed galactose was thickening of basement membrane.

Local influences in the eye apparently play an important role in the development of diabetic retinopathy. Current hypotheses about the pathogenesis of the retinopathy do not account adequately for such differences in the tissue distribution of vascular lesions.