Pathological changes induced by avian encephalomyelitis virus in developing goose (anser anser) embryos

44 7. SUMMARY The aim of this study was to investigate macroscopic and microscopic changes induced by Avian Encephalomyelitis Virus (AEV) in goose embryos, onehundred and eighty embryonated goose eggs were used for this purpose. Onehundred and twenty five of these eggs were infected and fifty five of them were used as a control group. Twelve-day-old embryos were inoculated in yolk sac with 0.1 ml viral suspension ( AEV- Van Roekel strain, EİDso İO3). After the inoculation, the eggs were candled at the same time of the day in a dark room twice a day for the detection of death embryos. Death occurring before the first seventy two hours of the inoculation were not taken into the consideration. On the other days of the incubation period, each day 8 alive embryonated eggs from the control group and 10 together with the dead ones from the infected group were opened. The rump lengths and widths and weights of embryos were measured and weighed. By measuring the approximate value and standard divergene of the data gained, the T - test was applied. After the necropsy, tissue samples from the brain, cerebellum, spinal cord, proventriculus, gizzard, pancreas, lungs, liver, heart muscle, kidney, spleen, bursa Fabricius, skeletal muscle, and eyes samples were taken and processed routinely for parrafin section. Tissue sections were examined under the light microscope. Such macroscopic finding in embryos as stunting, hydrocephalus, torticollis, deformities in feet and knee joints, twisting in fingers were the main findings observed. Among the control and infected group embryos, the statistical difference was firstly observed in the 3tn group as a rump width (P < 0.01) and after the 4tn group significant statistic difference was observed in all parts of the body (P < 0.01, P < 0.001).45 Mainly the microscopic changes peculiar to the infection was observed in the central nervous system. These findings included oedema, vascular proliferation, gliosis, neuronal degeneration, and necrosis. Apart from this on the 27th and 28th days of the incubation, increased thickness of vascular wall was observed in the brain. Vascular proliferation and oedema together with astrocytic reaction in the cerebellum, degeneration and necrosis in Purkinje cells were detected. In the spinal cord; oedema, neuronal degeneration and necrosis, and in the spinal ganglions, ganglionitis were determined. In the skeletal muscles; degeneration, necrosis, dystrophy and sarkolemmal proliferation were observed. As a result, it was determined that AEV Van Roekel strain induced spesific pathomorphologic changes along with deaths in goose embryos as in other avian species.