Abstract
Histological observations were performed on the schizonts of Japanese Theileria sergenti in three calves necropsied 8 and 10 days after application of nymphal Haemaphysalis longicornis infected with T. sergenti. In all the three calves, schizonts were observed in the cytoplasm of huge cells formed in the drainage lymph nodes, liver and spleen. The huge cells were 50 to 200 μm in diameter. Schizonts had granular appearance and an irregular shape and were 1 to 7 μm in diameter. Ultrastructurally, schizonts had more than on nuclei and were formed in the unit enlarged cell. Schizonts showed a specific reaction against anti-T. sergenti anti serum, therefore, it was concluded that the schizonts were those of T. sergenti histologically.
