| 166,7-days old healthy ducklings were divided randomly into 2 groups, 100 for the tested group and 66 for the control group. The pathological model of New Duck Viral Hepatitis (NDVH) was duplicated through inoculating New Duck Hepatitis Vims (NDHV) intramuscularly. Observations of clinic symptoms, pathological changes of optical microscope and transmissional electron microscope were carried out on the ducklings, also, the serum biochemical value was determined 12 h, 24 h, 48 h, 96 h, 168 h, 336 h, 504 h and 672 h post inoculation, lymphocyteAcid- a -naphthyl-acetate esterase (ANAE) histo-chemical staining method, determination ofdifferent leukocytes were used to study the pathological model.The results showed mat: infected ducklings began to appear nerve symptoms such as inappetence, ataxia and kicking spasmodically with both legs 12-24 h post inoculation, and then died with their heads drawn back and their leg stretched The fastigium of death was the period 48-72 h post inoculation, and the mortality was 41%. The results of postmortem examinations showed that: swelling and hemorrhage appeared in liver, spleen had a change of swelling and appeared white and red in the surface; swelling and congestion in kidney, uric acid salt deposit in some ducklings; white focus in the surface of pancreas with the shape of pinpoint could be seen in some ducklings.The results of H.E. staining showed mat the major lesions of liver appeared hemonhagic and necrotic changes, which changed from hydropic degeneration 24 h post inoculation, to fatty degeneration and focal hemorrhage 48 h later; men to severe ballooning degeneration after 96 h, lightly hydropic degeneration and bill canaliculi hyperplasia could be seen even 672 h (4 weeks) post inoculation; the pathological changes of spleen appeared majorly after inoculating for 48 h, which appeared that the number of lymphocyte surround the white pulp reduced sharply, and that the appearance of foam cell when the reticular cell phagocytized lipidic material; focal hemorrhage occurred in the renal tubular epithelium 48 h post inoculation, and then 96 h,karyopyknosis in the proximal tubule and different size vesicles in the cytoplasm could be found; the lesion of pancreasappeared mostly after inoculating for 48-96 h, which appeared focal fatty degeneration; number of lymphocyte in the medulla of bursa of Fabricuis reduced sharply after inoculating for 48 h.The results of TEM (Transmissional Electron Microscope) showed that: after inoculating for 12 h, we could find dissolvation of hepatin, karyo pyknosis, and disappearing of organelle in liver. The ultra-structure of the liver which ducklings occurred nerve symptoms and had been killed showed that, it had massive, severe hemorrhage and fatty degeneration, and organelles in the cytoplasm dissolved and even disappeared, fatty vesicles in different size could be seen in the cytoplasm; it could be found in the spleen that swelling of lymphocytes, organelles in the cytoplasm and nucleus dissolved and even disappeared; the lesions of cerebrum were karyo pyknosis or even karyolysis, empty and bright area could be seen around the vas; the lesions of pancreas were mitochondria swelling, vacuolar degeneration, endoplasmic reticulum exceedingly distending, and some fatty lipid-like material could be found in the cytoplasm.The results of the serum biochemical value showed that: the level of serum GOT and GPT went up and rose to maximum 96 h post inoculation; the level of TP and ALB went down and decreased to minimum 96 h post inoculation; the level of UA increased a Iittlel68 h post inoculation. There were no significant changes of ChE and CRE.Blood ANAE+-lymphocyte ratio constantly rose after 48 hpost inoculation then began to fall to normal level until 504 h post inoculation. The results of WBC classifying counting showed that: heterophil ratio decreased, lymphocyte and monocyte ratio.There were no significant changes of eosinophil and basophil.So we could see that, there were certain differences between the DVH-I and...
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