Gut- Associated Lymphoid Tissue (GALT)

Organized lymphatic tissue occurs in the walls of the gastrointestinal tract in multiple forms. The collective name for such lymphatic cell aggregates in the intestinal walls is GALT (gut-associated lymphoid tissue ). This cross-section of an appendix shows a lot of lymphatic tissue with secondary follicles 1 in the submucosal tissue. Groups of T- and B-lymphocytes bulge into the intestinal lumen over each follicle. These regions are named domes or dome areas 2 . Normal mucous membranes of the large intestines with crypts 3 exist between these dome areas. A region between the follicles with densely packed small lymphocytes and postcapillary venules with high endothelium is called interfollicular region 4 . Vermiform appendix from a rabbit.

1 Lymph follicles, secondary follicles

2 Dome area

3 Mucous membrane of the large intestine

4 Inter follicular region

5 Tunica muscularis

Stain: azan; magnification: × 18

References

Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4^th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgart · New York .