Comparative anatomy and phylogenetic distribution of the mammalian cecal appendix.


Journal Article

A recently improved understanding of gut immunity has merged with current thinking in biological and medical science, pointing to an apparent function of the mammalian cecal appendix as a safe-house for symbiotic gut microbes, preserving the flora during times of gastrointestinal infection in societies without modern medicine. This function is potentially a selective force for the evolution and maintenance of the appendix, and provides an impetus for reassessment of the evolution of the appendix. A comparative anatomical approach reveals three apparent morphotypes of the cecal appendix, as well as appendix-like structures in some species that lack a true cecal appendix. Cladistic analyses indicate that the appendix has evolved independently at least twice (at least once in diprotodont marsupials and at least once in Euarchontoglires), shows a highly significant (P < 0.0001) phylogenetic signal in its distribution, and has been maintained in mammalian evolution for 80 million years or longer.

Full Text

Duke Authors

Cited Authors

  • Smith, HF; Fisher, RE; Everett, ML; Thomas, AD; Bollinger, RR; Parker, W

Published Date

  • October 2009

Published In

Volume / Issue

  • 22 / 10

Start / End Page

  • 1984 - 1999

PubMed ID

  • 19678866

Pubmed Central ID

  • 19678866

Electronic International Standard Serial Number (EISSN)

  • 1420-9101

Digital Object Identifier (DOI)

  • 10.1111/j.1420-9101.2009.01809.x


  • eng

Conference Location

  • Switzerland