Bursa-independent origin of Fc IgG receptor-bearing lymphocytes in chickens

On the basis of performed studies the following observations indicate that there is a bursa-independent origin of lymphocytes with Fc IgG receptors: (a) the first appearance of Fc positive cells is in fetal liver and bone marrow, (b) a relative low percentage of Fc receptor cells, as compared to B cells, occurs in the bursa during the embryonic and post-hatching period, (c) a far lower percentage of Fc positive cells than B cells is found in the spleen, (d) a normal level of Fc positive cells occurs in bursectomized birds, (e) a majority of these cells do not possess thymic or bursa antigen or surface immunoglobulin.