Riddle me this

The appendix used to be considered a vestigial organ, but this view has changed over the past decades.

Until recently, the human appendix has been regarded as a rudimentary part of the intestine. During the past few years, however, several studies have suggested its immunological importance for the development and preservation of the intestinal immune system 1. The appendix has been shown to have an important interaction with the intestinal flora 2, 3, 4. Considering the appendix as a ‘safe house’ for the commensal gut flora, these studies hypothesize that commensal bacteria can be reintroduced from the appendix in case of disease, and therefore the appendix can be considered as an important part of intestinal health. This literature review assesses the current knowledge concerning the immunological aspects of the vermiform appendix. By describing its normal physiology and the importance of its biofilm, and appraising its evolution and elucidating which aspects have changed or, more importantly, which have been preserved in the long history of its existence, a clearer understanding of its influence on the intestinal immune system will be provided.