a-short-review-of-histology

Non-encapsulated Lymphoid Tissue:

As well as being present in defined lymph organs, less defined accumulations of lymphoid tissue can be found
These types of lymphoid accumulation range from a cluster of small lymphocytes to fully organised lymphatic nodules in the loose connective tissue of the mucous membrane
In some locations there may be several lymphatic nodules clustered together
In the alimentary canal there are a number of locations where several lymphatic nodules may be clustered together
These areas include the tonsils in the pharynx, Peyer's patches in the ileum of the small intestine, and the appendix
In these locations, the lymphoid tissue lies in the lamina propria just deep to the surface epithelium
The lymphoid tissue may be so extensive that it extends into the submucosa
The lymphoid tissue in these locations monitors the presence of pathogens in the lumen of the gut tube and protects the gut wall from invasion by such pathogens