Page 694 - Veterinary Immunology, 10th Edition

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FIG. 22.3 Lymphoid follicle found in the bifurcation of an airway in
a section of calf lung. This type of bronchus-associated lymphoid
tissue is a key component of the defenses of the respiratory tract.
(From a specimen provided by Drs. N.H. McArthur and L.C. Abbott.)

FIG. 22.4 Two key defensive mechanisms are employed on
mucosal surfaces. The most important is immune exclusion, an
effect primarily mediated by IgA. If antigens gain access to the
mucosa, they are destroyed through IgG- and IgE-mediated
processes by immune elimination.

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