Ultrastructural Pathologic Observation on the Gut-Associated Lymphoid Tissues of Sacculus Rotundus o

<正> Ultrastructural pathological changes in the gut-associated lymphoid tissues of sacculus rotundus (SR) of rabbits infected with rabbit haemorrhagic disease virus (RHDV) were first observed. There were numerous holes at the luminal and basement membrane surfaces of the dome epithelium (DE), consistently accompanied by necrosis of lymphocytes and M-cells, and pronounced depletion of lymphocytes in the domes and follicles, decrease of DE complex with formation of pseudomembranous structure on the surface of the dome epithelium. A specific finding in lymphocytes and macrophages was that severe destruction detraction of the membrane of rough endoplasmic reticulum(RER) was accompanied by conspicious increase of solitary, ribo-some-like particles in the cytoplasm, with appearances of intranuclear particles and intranuclear inclusions. It was found that there were many round and dense virion-like particles, with 26 nm in diameter, in the nuclei and cytoplasm of lymphoctes, plasma cells, macrophages and fibroblas