The Prevention of Lymphoid Leukosis with Androgens

THE bursa of Fabricius plays a key role in the development of lymphoid leukosis (LL) (Peterson et al., 1964, 1966). Surgical removal of the bursa, even though delayed up to 4–5 months of age, prevented the occurrence of this neoplasm. However, bursectomy had no effect on occurrence of erythroblastosis or osteopetrosis, neoplasms also caused by LL virus. Removal of the thymus, a lymphoid organ similar in several respects to the bursa of Fabricius, did not significantly affect the occurrence of any of these neoplasms. This is consistent with the hypothesis (Cooper et ah, 1968) that LL is a neoplasm of the bursa-dependent lymphoid system. The primary neoplasm occurs in the bursa follicles and the malignant cells metastasize to the vital visceral organs eventually causing death. Androgens have been used to prevent the development of the bursa of Fabricius when administered to embryos (Meyer et al., 1959; Glick and Sadler,…