Abstract
Aseptic bone necrosis was observed in the tibia of 23 ICR mice. Histological changes were characterized by a loss of marrow tissue with proliferation of connective tissue and bone necrosis with empty osteocytic lacunae. Focal necrosis was confined beneath the articular cartilage. Extensive necrosis was present in half or all of the epiphysis. Massive necrosis was noted in the diaphysis of one animal. It was considered that focal necrosis might be related to degenerative osteoarthritis, and that extensive and massive necroses might have been caused by a disturbance of the blood supply.