Bioscientifica Proceedings

Summary. The appearance and production of an early pregnancy factor (EPF) has been studied in sheep and cattle. This factor can be detected in serum and tissues of pregnant animals by its synergistic action with antilymphocyte serum in reducing the number of rosettes formed in a rosette inhibition test. The range of the rosette inhibition titre for serum from non-pregnant animals was 4–10. Values higher than these were considered to indicate the presence ...