1964 Volume 19 Issue 11 Pages 447-457
It is the purpose of this peport to present the findings concerned with the role of the thymus and Bursa of Fabricius (B. F.) in the development of lymphoid tissue and immunologic capacity in chicken. Using Rhode-Horn F1 as experimental chicken, the authors performed surgical thymectomy and bursectomy at the time of hatching, or hormonal bursectomy by the injection of testosterone propionate into 5-day chick 4embryos. The following results were obtained.
1) It was confirmed that lymphocytopoiesis in the thymus and B. F. begins in epithelial buds of chick embryos at 12-14 days of incubation, and before hatching lymphoid tissue is confined to both the organs. In fact, the spleen and intestine are as yet lacking in demonstrable lymphoid follicles at hatching, and the development of lymphoid tissue in thse organs commences to appear 1-2 weeks after hatching.
2) Chiken thymectomized or bursectomized at hatcing showed a slight diminution in lymphocyte population of the blood stream and poor development of lymphoid follicles in the spleen and intestine. Furthermore, extirpation of both the organs resulted in the striking depression of lymphocyte level in the blood stream and of the development of lympoid follicles.
3) Complete bursectomy, surgical or hormonal, weakened or removed the ability of the birds to produce the antibodies in response to typhoid bacilli and sheep erythrocytes introduced. However, thymectomy had no influence on the production of circulating antibodies.
4) Thymectomy prolonged remarkably the elimination of homologous erythrocytes labelled with 51Cr from the blood stream, while bursectomy prolonged slightly. The life-span of homologous erythrocytes in the blood stream of the group in which both the organs were extirpated reached near that of the autologous erythrocytes in the normal group. This may be taken to indicate that chicken can be rendered tolerant toward homologous erythrocytes by thymectomy at hatching.
From the above-described data, the authors can suppose that the thymus and B. F. are primarily lymphopoietic organs in embryonal and neonatal life, and make a major contribution to the central supply of precursory lymphoid cells, capable of becoming immunologically competent, to lymphoid follicles of whole body. It may be, morever, suggested that descendants of lymphoid cells originating in both the organs have different functions from each other in immunologic responses, i. e., lymphoid cells descending from the B. F. are responsible for the circulating antibody production through the differentiation to plasma cells by antigenic stimuli, and lymphoid cells descending from the thymus are responsible for the homograft immunity, probably, through the cellular antibody of lymphocytes.
