Page 335 - Veterinary Immunology, 10th Edition
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FIG. 12.4 The bursa of Fabricius obtained from a 1-week-old
chicken. It has been cut open to reveal the folds inside.
Structure
Like the thymus, the bursa consists of lymphocytes embedded in
epithelial tissue. This epithelial tissue lines a hollow sac connected
to the cloaca by a duct. Inside the sac, folds of epithelium extend
into the lumen, and scattered through the folds are round masses of
lymphocytes called lymphoid follicles (Fig. 12.5). Each follicle is
divided into a cortex and a medulla. The cortex contains
lymphocytes, plasma cells, and macrophages. At the
corticomedullary junction there is a basement membrane and
capillary network on the inside of which are epithelial cells. These
medullary epithelial cells are replaced by lymphoblasts and
lymphocytes in the center of the follicle. Specialized
neuroendocrine dendritic cells of unknown function surround each
follicle.
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