CAPILLARY LESIONS DEVELOP IN RETINA RATHER THAN CEREBRAL-CORTEX IN DIABETES AND EXPERIMENTAL GALACTOSEMIA

Objective: To isolate microvessels from cerebral cortex of dogs with a lloxan-induced diabetes and dogs with experimental galactosemia to com pare the prevalence of microvascular lesions in cerebral cortex with t hat in retina. Methods: Microvessels were isolated from cerebral corte x of experimental animals using a sieving method, and compared with th e retinal vasculature isolated from the same animals using the trypsin digestion method. Results: Dogs with diabetes or experimental galacto semia of 5 years' duration had retinopathy that was morphologically in distinguishable from that of humans with diabetes, including microaneu rysms, 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. C onclusions: Local influences in the eye apparently play an important r ole in the development of diabetic retinopathy. Current hypotheses abo ut the pathogenesis of the retinopathy do not account adequately for s uch differences in the tissue distribution of vascular lesions.