The structure of the bursa of Fabricius in wild birds.

B. Glick et all,2 found that the antibody-producing ability is markedly re duced when the bursa of Fabricius (abbreviated as BF) of the newly-hatched chick is removed. Thus the function of this organ which is specific for birds received a great deal of attention. With the comparative study of bursectomy and thymectomy, it has been ascertained that the BF and the thymus play distinctive roles in establishing acquired immunity, i.e., the BF is implicated in the produc tion of serum antibody and the thymus in the production of cellular immunity. Moreover, Cooper et a13" investigated the relationship between the central lym phoid tissue and the peripheral lymphoid tissue, and suggested the separation of the immunological system of an animal into two systems, i.e., the thymus-de pendent and the bursa-dependent. Study of the BF has also expanded into the medical field, however, most of the studies were done on chickens, while only a few studies concerned the domes tic fowls such as the Japanese quail5,6 and the duck. The structure and function of the BF of the Japanese quail had been studied in this laboratory, and research was extended to wild birds since the necessity arose several years ago. The Passerine species of wild birds were especially subjected to a structural examination of the BF. The newly-hatched chick of Passer montanus was subjected to bursectomy and then utilized in an immu nological experiment. The results of this immunological experiment with Passer montanus were different from that for the domestic fowl which had previously been obtained. The details will not be mentioned here, however, because of in sufficient data due to technical difficulties. The structure of the BF of wild birds will be explained in this paper to pro