Present study was designed to analyze the histological and cytological changes of lymphocyte homing in the non-infected and duck tembusu virus (DTMUV) infected duck spleen. At first, we investigated the non-infected structure that facilitate the lymphocyte homing. Under light and electron microscopy, results showed that sheath capillaries were located in the white pulp of spleen and the endothelial cells of sheath capillaries were cuboidal in shape, which is a typical character of high endothelial venules. To monitor the lymphocyte homing, CFSE (5,6- carboxy fluoresceindiacetate succinimidyl ester)-labeled lymphocytes intravenously injected into non-infected ducks showed in the periellipsoidal sheaths (PELS), which proved that lymphocytes can return to the spleen through sheath capillaries. Furthermore, proteoglycans (PGs) associatedwith homing factors, were positivity observed in the sheath capillaries and PELS by Colloidal Iron staining. It is suggested that PGs is associated with lymphocyte homing. The results of DTMUV infection experiment showed that PELS appeared vacuolized in the PELS at 3dpi. The spleen tissue gradually recovered on 5dpi and 7dpi. Besides, the lymphocytes increased around sheath capillaries and the expression of PGs in sheath capillaries became more after virus infection. Meanwhile, the gaps between endothelial cells were enlarged and the lymphocytes were mainly in the lumen and basement membrane. In conclusion, lymphocytes could recruit into the spleen by sheath capillaries and PGs participated and promoted the lymphocytes homing, suggesting that the unique high endothelial capillaries favor lymphocyte homing, which promotes tissue repairment and antigen clearance in the duck.

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