Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Veterinary Microbiology and Preventive Medicine



First Advisor

Lawrence H. Arp


The structure, development, lymphoid cell types, and capacity for antigen uptake of bronchus-associated lymphoid tissue (BALT) in chickens and turkeys were studied using light and electron microscopy, immunocytochemistry, and image analysis. The structure of avian BALT was very similar to mucosa-associated lymphoid tissues described in other species and tissue sites. Individual BALT nodules were composed of a population of lymphocytes covered by a modified epithelium. Age-related changes in BALT structure were observed, which may influence epithelial permeability to antigens and the potential for interaction between epithelial cells and lymphocytes;The number of IgA-, IgM-, and IgG-producing cells per unit area of BALT tissue was determined in 1-day, 1-, 2-, 3-, 4-, 6-, and 8-week old chickens. Comparisons were made among immunoglobulin isotypes, ages, and two tissue regions (BALT-associated mucosa and mucosa not infiltrated with lymphocytes). There were no immunogobulin-producing cells in 1-day old chickens, IgG+ cells only in 1-week old chickens, and cells of all three isotypes in chickens 2 weeks of age and older;Monoclonal antibodies were used to label T lymphocyte subpopulations (CD4 and CD8) and B lymphocytes (CB3) in chicken BALT. In general, CD4+ cells formed tight clusters capping germinal centers and were associated with blood vessels in BALT. CD8+ cells were diffusely scattered throughout lymphoid nodules, extending up to and into the epithelium. CB3+ cells predominated in germinal centers and overlapped CD4+ clusters around germinal centers;To monitor ability of BALT epithelium to take up antigens, three tracers (ferritin, live Bordetella avium, and ultraviolet-killed B. avium) were instilled into tracheas of 3-week old turkeys. Ferritin was found in both ciliated and non-ciliated epithelial cells and in basal extracellular spaces. Both killed and live B. avium were taken up by ciliated and non-ciliated cells of the BALT epithelium, and by intraepithelial macrophages;The results of these studies support a role for BALT in initiation of respiratory humoral immune responses in chickens and turkeys.



Digital Repository @ Iowa State University,

Copyright Owner

Jane Ann Fagerland



Proquest ID


File Format


File Size

179 pages