Caeca

Cross section of the caecum of a chicken (HE): detail of the caecal tonsil

Two tonsillar units separated by a septum of connective tissue are shown.

The central crypt is lined by a columnar epithelium invaded with lymphocytes (lymphoepithelium). The lymphoid follicles contain mostly B lymphocytes while the interfollicular region is especially rich in T lymphocytes.

The cecal tonsils are believed to play an important role in the maturation of B lymphocytes in addition to the Bursa of Fabricius.