Anatomical distribution of T and B lymphocytes identified by immunohistochemistry in the chicken spleen.

Antisera against chicken bursal and thymic lymphocytes were raised in rabbits. They were made specific for the target T or B cells by appropriat absorption and then used for immunohistochemical identification of T and B lymphocytes in tissue sections of chicken spleen, applying the unlabeled antibody enzyme method. Lymphocyte reacting with anti-chicken-thymus globulin predominated in the periarteriolar lymphatic sheaths and in the red-pulp cords. A few of these lymphocytes were localized between the periellipsoid lymphatic tissue and in germinal centers. The periellipsoid lymphocytes around the Schweigger-Seidel sheaths consisted of lymphocytes positive with anti-chicken-bursa-cell globulin. The majority of lymphocytes in the germinal centers were labeled also by anti-chicken bursa-cell globulin. Age-dependent changes in the anatomical localization of T and B lymphocytes are described between late embryonic development and an age of 2 years. The different conditions of avian and mammalian T and B cell distribution in the spleen were considered.