Abstract

Fifty broiler chickens infected with non absorbed yolk sac were colleted from private chicken farms in Mosul province, these chicks where used to study their gross and histological changes in the livers of these chickens. Infected chickens were divided into three groups (8 days, 11 days, 18 days) respectively. A group of non infected chickens were used as a control group for each age. The most prominent gross pathological changes of the livers of the three groups were variable ranging from sever congestion to palness in the first group, while the second group revealed only congestion of the livers. The third group showed congestion of the livers with multifocal areas of necrosis compared with control group. Histological changes of livers of the first group showed degeneration of hepatocytes with congestion of central veins. Sever changes were seen in the second group characterized by congestion of central veins with infiltration of inflammatory cells (lymphocytes) around the central vein. More sever changes were seen in the third group compared with the first and second group which characterized by presence of multifocal infiltration of inflammatory cells especially lymphocytes in hepatic tissue with coagulative necrosis of hepatocytes. In other samples mild fibrosis was seen around the central veins. More over subcapsular hemorrhage with dilatation of bile duct were seen. A case of non absorbed yolk sac were recorded at 47 days. The yolk sac contain caseous material which attached above the internal side of the cloaca.