The influence of embryonal bursectomy on benzpyrene-induced sarcoma of the chicken.

160 chickens hormonally bursectomized before hatching, and 160 controls were twice given a dose of 10 mg 3,4-benzo(a)pyrene 2 weeks and 6 weeks after hatching. After 24 weeks the controls had developed muscle sarcomas at a significantly higher rate than the bursectomized animals (49.6--32.1%). The tumors were identified as malignant polymorphocellular rhabdomyosarcomas in light and electron microscopy. When the experiment was stopped after 27 weeks, the controls showed more tumors than the bursectomized chickens (65.1% versus 58.9%). The effect of bursectomy lies in a prolongation fo tumor latency. The frequency of metastases is equally decreased to a significant degree (41.7% versus 21.7%). These results are interpreted as an illustration of the disturbed equilibrium between the T and B cell responses.