Myocardial cytoplasmic inclusions in chickens with haemangioma and lymphoid leukosis.

Twelve of 23 adult chickens (23 to 28 weeks old) affected naturally with haemangioma and lymphoid leukosis (LL) had basophilic cytoplasmic inclusions in myocardial cells. The inclusions were oval, elongated, round or pleomorphic in shape and were rich in RNA. Electron microscopy revealed that the inclusions comprised of electron-dense small granules and doughnut-shaped particles. The significance of inclusions in LL virus infections and LL virus-induced tumours is discussed.