Thymus- and bursa-dependent areas in duck lymph nodes.

The thymus (T)-and bursa (BF)-dependent areas of the duck lymph node were histologically examined by means of chemical bursectomy using cyclophosphamide-treatment , surgical thymectomy, and/or X-ray irradiation. The T-dependent area was represented by the deep area of lymphatic nodules comprised of small lymphocytes. The BF-dependent one was represented by lymphatic cords consisting of small and medium-sized lymphocytes, and possibly by germinal centers. On the other hand, the para-sinusoidal area of lymphatic nodules and the existence of plasma cells seemed to be independent from both the thymus and the bursa of Fabricius. The relationship between avian and mammalian lymph nodes was discussed with special reference to T-, BF-, and bone marrow (BM)-dependent systems.