A scanning electron microscope study of the caecal tonsil: the identification of a bacterial attachment to the villi of the caecal tonsil and the possible presence of lymphatics in the caecal tonsil.

A scanning electron microscope (SEM) was used to compare the proximal region (PR) and distal region (DR) of the caecum. The caecal tonsil (CT) occupied the initial 4-10 mm of the PR. Villi were present in the PR and absent from the DR. Segmented structures were attached to the surface of PR. Transmission electron microscopy (TEM) revealed these structures to be bacteria. No difference in surface morphology could be discerned between the CT and the remainder of the PR. Lymphatic vessels were observed in the CT by employing TEM.