Cross-sectional histological sections of the infected tibias. In the animals with S. aureus (52/52A/80) (a), S. epidermidis (ATCC 35983) (b), or S. epidermidis (T-54580) inoculum (c) (van Gieson stains). In animals with S. aureus inoculum, drastic osteomyelitic changes is seen characterized by a nearly circumferential periosteal reaction, new bone formation, and sequester formation and infiltration of polymorphonuclear leukocytes with occasional microabscesses. Animals with S. epidermidis (ATCC 35983) inoculum did not show signs of infection. In these animals, closure of cortical defect and only a limited number of inflammatory cell infiltrate was seen. In animals with S. epidermidis (T-54580) inoculum, signs of chronic/subacute osteomyelitis are seen characterized by periosteal reaction with periosteal sclerosis, infiltration of lymphocytes and plasma cells, and bone marrow showing signs of fibrosis.