The irises of seven chickens with lesions of spontaneous ocular leukosis were examined by light and electron microscopy. Histologically, the abnormal contents of the irises included necrotic striated musculature, mononuclear cells, and granulocytes. Observed by electron microscopy, viral particles were embedded in the basement membrane of striated muscle cells, in membrane-bound vesicles in muscle cells, in proximity to pigmented epithelial cells, and in the lumen and basement membrane of endothelial cells of capillaries of the iris. Necrosis of striated muscle cells occurred where large masses of viral particles were observed extracellularly and in vesicles in the cell. Particles budded from the cell membrane and the membrane surrounding vesicles.
It appeared that depigmentation of the irises of chickens with ocular leukosis was correlated with necrotizing changes of the striated muscle cells in the irises.
Supported in part by a grant (H-6580) from the National Heart Institute, Florida Agricultural Experiment Stations Journal Series No. 3010.