Cytoplasmic and nuclear inclusions in epidermal cells of pigs inoculated with vaccinia viruses.

The morphology of cytoplasmic and nuclear inclusions in the epidermal cells of pigs inoculated with vaccinia viruses was studied. Cytoplasmic inclusions observed were those corresponding to type B described by KAMAHORA et al. (11). They were subdivided into three morphologic types and were tentatively designated type B-1, B-2 and B-3, respectively. Type B-1 was eosinophilic, granular in structure, relatively large in size, and round or ovoid in shape. Type B-2 was poorly stained with hematoxylin and eosin, granular in structure, small in size, and was a relatively elongated mass along the nuclear membrane. Type B-3 was basophilic, and was a uniformly stained small body. Electron microscopically, various aberrant findings were seen in most of the cytoplasmic inclusions and they differed depending on their types. Nuclear inclusions could also be classified microscopically into three morphologic types. Type 1 was eosinophilic or neutrophilic and had a homogeneous structure. Type 2 was eosinophilic and fibrillar in structure. Type 3 appeared as small eosinophilic bodies. Electron microscopically type 1 was found to be composed of fine fibro-granular structures, type 2 was found to be composed of relatively long filaments which resembled tonofilaments, and type 3 consisted of unique fibrillar structures.