Anatomical structure of largely lymphoid tissue that functions in cell-mediated immunity by being the site where T cells develop.
Comment:
[homology-note] "A thymus develops in all vertebrates from the endodermal epithelium of certain pharyngeal pouches and from the adjacent ectodermal epithelium. In fishes, all the pouches, or the first four, contribute to thymus formation, but in tetrapods, the number is more restricted. In mammals, only the third and fourth are involved, and the contribution of the third is by far the greater.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000253", ontology="VHOG", source="ISBN:978-0878932504 Gilbert SF, Developmental Biology (2006) p.558", source="http://bgee.unil.ch/"}