Role of the Thymus and the Bursa of Fabricius in Immune Reactions in Chickens II.

Role of the Thymus and Other Central Lymphoid Tissues in Immunological Disease

“…Thymectomy, either early or late and with or without the addition of treatments designed to destroy peripheral lymphoid ele ments, does not prevent the subsequent development of some small lym phoid cells, lymphoid cells of the germinal centers, and immature and mature plasma cells (21,22,54,63,107). In birds, the central lymphoid organ for this cell population is the bursa of Fabricius (1,16,18,19,21,22,108,109). In mammals, a central lymphoid organ for this immunologically competent cell system has not been unequivocally demonstrated but evidence which suggests that mammalian Peyer's patch-type of intestinal lymphoid tissues serve as an equivalent of the avian bursa, has been presented (24).…”

“…It was a chance event that bursectomized birds were challenged with an antigen for a classroom demon stration of antibody production, thus leading to one of the most important single discoveries in immunobiology. Bursa removal in the first weeks of life significantly reduces antibody responsiveness to subsequent antigenic stimulation (1,19,22,108,(117)(118)(119) . The resulting defect in antibody re sponsiveness is greatest if the bursa is removed at the time of hatching.…”

“…Hormonal bursectomy, by treatment of chick embryos with testosterone, suppresses development of antibody responsiveness even more completely than surgical bursectomy at hatching (15,16,108,109,118,120) . Both means of bursectomy reduce the numbers of plasma cells which subsequently develop throughout the body, as well as the quantity of circulating gamma globulin (15,16,19,22,109,(121)(122)(123)(124). However, bursectomy by either of these means does not com pletely prevent plasma cell differentiation or gamma globulin synthesis.…”

“…COOPER, GABRIELSEN & GOOD I t further seems evident that there is horizontal division in immunologic development (15)(16)(17)(18)(19)(20)(21)(22)(23)(24) . This horizontal division is defined as compartmen talized differentiation of two distinct lymphoid systems (21-24) j each system has its own central lymphoid tissue and the cells of each system exhibit dis tinct morphologic and functional characteristics.…”

The Effect of Bursa Fabricius Removal in Day-Old Chicks Upon Growth Performance, Blood and Spleen Characteristics

“…Some workers (Glick, 1963(Glick, , 1969Sato, 1964a, 1964b;Isakovic and Janovic, 1964) did not find a significant influence on blood characteristics in bursectomized birds. The present work agrees with their findings on haematocrit values and the total number of leucocytes.…”