Intratibial Moloney sarcoma virus-induced osteosarcoma in the rat: tumor incidence and pathologic evaluation.

Osteosarcomas were induced in approximately 80% of young New Zealand Black rats by the intratibial inoculation of Moloney murine sarcoma virus from day 1 to day 5 after birth. The neoplasms were composed of a spectrum of well-differentiated to poorly differentiated osteoblasts, osteocytes, and osteoclasts. Budding of C-type viral particles was associated with tumor induction. Compared to rats inoculated on day 1 after birth, rats inoculated at 4 days of age developed consistently more osteoproliferative bone tumors that often were associated with hypercalcemia, increased serum alkaline phosphatase, and elevated urinary hydroxyproline.