Editing Thymus (section)

==Other animals==
The thymus is present in all [[Gnathostomes|jawed vertebrates]], where it undergoes the same shrinkage with age and plays the same immunological function as in other vertebrates. Recently, in 2011, a discrete thymus-like lympho-epithelial structure, termed the ''thymoid'', was discovered in the gills of larval [[lamprey]]s.<ref>{{cite journal | vauthors = Bajoghli B, Guo P, Aghaallaei N, Hirano M, Strohmeier C, McCurley N, Bockman DE, Schorpp M, Cooper MD, Boehm T | display-authors = 6 | title = A thymus candidate in lampreys | journal = Nature | volume = 470 | issue = 7332 | pages = 90–4 | date = February 2011 | pmid = 21293377 | doi = 10.1038/nature09655 | bibcode = 2011Natur.470...90B | s2cid = 4417477 }}</ref> [[Hagfish]] possess a protothymus associated with the pharyngeal velar muscles, which is responsible for a variety of [[immune system|immune]] responses.<ref>{{cite journal | vauthors = Riviere HB, Cooper EL, Reddy AL, Hildemann WH |year=1975 |title=In Search of the Hagfish Thymus |journal=American Zoologist |volume=15 |issue=1 |pages=39–49 |jstor=3882269 |doi=10.1093/icb/15.1.39  |url=https://academic.oup.com/icb/article-pdf/15/1/39/6051623/15-1-39.pdf |doi-access=free }}</ref>

The thymus is also present in most other vertebrates with similar structure and function as the human thymus. A second thymus in the neck has been reported sometimes to occur in the [[mouse]].<ref>{{cite journal | vauthors = Terszowski G, Müller SM, Bleul CC, Blum C, Schirmbeck R, Reimann J, Pasquier LD, Amagai T, Boehm T, Rodewald HR | display-authors = 6 | title = Evidence for a functional second thymus in mice | journal = Science | volume = 312 | issue = 5771 | pages = 284–7 | date = April 2006 | pmid = 16513945 | doi = 10.1126/science.1123497 | bibcode = 2006Sci...312..284T | s2cid = 24553384 | doi-access = free }}</ref> As in humans, the [[guinea pig]]'s thymus naturally atrophies as the animal reaches adulthood,<ref>{{cite book |last1=Suckow |first1=Mark A. |last2=Stevens |first2=Karla A. |last3=Wilson |first3=Ronald P. |title=The Laboratory Rabbit, Guinea Pig, Hamster, and Other Rodents |date=2012 |publisher=Academic Press |isbn=978-0-12-380920-9 |pages=583 |url=https://books.google.com/books?id=HhEs-xsYp6IC&q=guinea+pig+thymus&pg=PA583 |language=en}}</ref> but the athymic [[Guinea pig#In scientific research|hairless guinea pig]] (which arose from a spontaneous laboratory mutation) possesses no thymic tissue whatsoever, and the organ cavity is replaced with [[cyst]]ic spaces.<ref>{{cite book |last1=Gershwin |first1=M. Eric |last2=Merchant |first2=Bruce |title=Immunologic Defects in Laboratory Animals 1 |date=2012 |publisher=Springer Science & Business Media |isbn=978-1-4757-0325-2 |page=289 |url=https://books.google.com/books?id=vZS1BwAAQBAJ&q=hairless+guinea+pig+athymic&pg=PA291 |language=en}}</ref>