Scientists discover the function of human appendix
US-based researchers have identified that the human appendix, which is often viewed as a vestigial organ with little-known use, may serve as a reservoir for beneficial gut bacteria. Mammals with an appendix were found to have higher concentrations of lymphoid tissue in the cecum, a pouch from which the appendix develops, suggesting that appendix serves as a secondary immune organ.
Washington, Jan 10 (PTI) The human appendix, which is thought to be of little use to the body, may actually serve as a reservoir for beneficial gut bacteria, a new study has found. The appendix, a narrow pouch that projects off the cecum in the digestive system, has a notorious reputation for its tendency to become inflamed (appendicitis), often resulting in surgical removal. Although it is widely viewed as a vestigial organ with little known function, the new study suggests that the appendix may serve an important purpose. In particular, it may serve as a reservoir for beneficial gut bacteria. Several other mammal species also have an appendix and studying how it evolved and functions in these species may shed light on this mysterious organ in humans. Researchers from the Midwestern University Arizona College of Osteopathic Medicine in the US gathered data on the presence or absence of the appendix and other gastrointestinal and environmental traits for 533 mammal species. They mapped the data onto a phylogeny (genetic tree) to track how the appendix has evolved through mammalian evolution, and to try to determine why some species have an appendix while others do not. They discovered that the appendix has evolved independently in several mammal lineages, over 30 separate times, and almost never disappears from a lineage once it has appeared. This suggests that the appendix likely serves an adaptive purpose. Looking at ecological factors, such as diet, climate, how social a species is, and where it lives, they were able to reject several previously proposed hypotheses that have attempted to link the appendix to dietary or environmental factors. Instead, they found that species with an appendix have higher average concentrations of lymphoid (immune) tissue in the cecum. This finding suggests that the appendix may play an important role as a secondary immune organ. 