Observations on the in vitro multiplication of bovine lymphoid cells infected with Theileria annulata schizonts.

The multiplication of a bovine lymphoid cell line infected with Theileria annulata schizonts was studied. In cells dividing mitotically, the schizont occupied a central position during the late stages of the division and was shared by the two newly formed cells. Binucleated cells with schizonts located between the nuclei were also observed. No definitive conclusions can be drawn as to whether these cells are stages in amitotic division or result from fusion of infected cells. Wide variations in the number of schizont nuclei per infected cell occurred with an average of 12.2 nuclei per schizont. The great majority of the cells contained 4 to 16 schizont nuclei.