Search results
Results from the WOW.Com Content Network
Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
The human appendix averages 9 cm (3.5 in) in length, ranging from 5 to 35 cm (2.0 to 13.8 in). The diameter of the appendix is 6 mm (0.24 in), and more than 6 mm (0.24 in) is considered a thickened or inflamed appendix. The longest appendix ever removed was 26 cm (10 in) long. [3]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
The appendix, long misunderstood as a vestigial organ, is now recognized as a key MALT structure, playing an essential role in B-lymphocyte-mediated immune responses, hosting extrathymically derived T-lymphocytes, regulating pathogens through its lymphatic vessels, and potentially producing early defenses against diseases. [1]
If a structure was once called vestigial, but is now known to be functional, then calling it "Functioning Vestigial Structures" violates the definition of vestigial, because by definition, it is not vestigial. It was previously called vestigial, but that was a mistake. It is not correct to call the vermiform appendix vestigial.
The human appendix is a vestigial organ thought to serve no purpose. Appendicitis , an infection of this organ, is a certain death without medical intervention. "During the past few years, however, several studies have suggested its immunological importance for the development and preservation of the intestinal immune system."
Researchers collected 25 years-worth of information on more than 500,000 women, and compared a history of one or both of the surgeries with the pregnancies.
Presumably that consensus is still evolving and both views should be represented, but the current state of the field in 2015 is that the appendix is not vestigial. The human horripilation response (goose bumps) is another example that is frequently repeated in the media, but is actually rather controversial, and you don't need research to ...