Pathology of liver and other visceral organs of highly productive layer lines infected with subgroup a and c rous sarcoma virus*

Pathogenesis of Rous sarcoma virus subgroup A (BS-RS V) and subgroup C [RS V (RA V-49)] infected embryos and chicks of highly productive layer lines (IWJ, IWG and IWC) was studied by inoculating 11-day-old embryos via the chorioallantoic membrane (CAM) route. No pathological changes were observed in liver of fully developed infected prehatching embryos. The histological changes in liver such as engorgement of hepatic blood vessels, degeneration of fibroblasts within hepatic lobules, accumulation of fibroblasts in liver parenchyma causing compression of hepatic lobules and loss of radiating arrangement of the hepatic cords were first observed in 2-day-old chick. Multiple foci of tumourous growth comprising compact masses of immature fibroblasts resembling fibrosarcomatous changes were detected. Metastasis occurred in heart, lungs, spleen, kidneys and gonads. It can be concluded that liver is the target organ for tumourogenesis following RS V infection and can therefore be effectively used as a marker for genetic studies.