Secondary lymphoid nodule

These secondary nodules in a tonsil demonstrate well-developed germinal centers capped by distinct mantles of unstimulated B cells. The nodule, which also contains macrophages and antigen-presenting cells, is supported by a stroma of reticular connective tissue. Tonsils filter tissue fluid in the mucosae of the oral and pharyngeal cavities. Pharyngeal tonsil, 200x

These secondary nodules in a tonsil demonstrate well-developed germinal centers capped by distinct mantles of unstimulated B cells. The nodule, which also contains macrophages and antigen-presenting cells, is supported by a stroma of reticular connective tissue. Tonsils filter tissue fluid in the mucosae of the oral and pharyngeal cavities. Pharyngeal tonsil, 200x

These secondary nodules in a tonsil demonstrate well-developed germinal centers capped by distinct mantles of unstimulated B cells. The nodule, which also contains macrophages and antigen-presenting cells, is supported by a stroma of reticular connective tissue. Tonsils filter tissue fluid in the mucosae of the oral and pharyngeal cavities. Pharyngeal tonsil, 200x

The pharyngeal tonsil or adenoid is located in the roof of the pharynx and is covered by a ciliated, pseudostratified columnar epithelium similar to that seen in the respiratory system.