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الملخص
This research aim to study pathological changes caused by lentogenic NDV vaccine in broiler chickens.
The chickens were vaccinated against Newcastle disease virus with live attenuated vaccine (cloned strain) through drinking water. Histologic samples were collected for studying histopathologic changes in thymus and bursa of fabricius after 2, 24, 48, 96 and 144 of vaccine administration. Paraffin sections were made and stained with Hematoxline-Eosin and methylene blue stain.
Macroscopic exam revealed hemorrhagic points and congestion after 2 hours of vaccine administration in thymus. Whereas no macroscopic pathological changes were observed in bursa of fabricius.
Microscopic exam revealed congestion of blood vessels, hemorrhage and light necrosis of lymphoid cells in thymus, hypertrophy of Myoid cells and infiltration of Heterophils and Mast cells.
Infiltration of Heterophils was observed locally around lymphoid follicles in bursa of fabricius, also Mast cells increased around lymphoid follicles.
Conclusion: obvious pathological changes occurred in thymus after vaccination by cloned strain of NDV. local infiltration of Heterophils and Mast cells was observed in bursa of fabricius during this study.