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Dev Dyn 2013 Feb 01;2422:164-78. doi: 10.1002/dvdy.23905.
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Early development of the thymus in Xenopus laevis.

Lee YH , Williams A , Hong CS , You Y , Senoo M , Saint-Jeannet JP .

BACKGROUND: Although Xenopus laevis has been a model of choice for comparative and developmental studies of the immune system, little is known about organogenesis of the thymus, a primary lymphoid organ in vertebrates. Here we examined the expression of three transcription factors that have been functionally associated with pharyngeal gland development, gcm2, hoxa3, and foxn1, and evaluated the neural crest contribution to thymus development. RESULTS: In most species Hoxa3 is expressed in the third pharyngeal pouch endoderm where it directs thymus formation. In Xenopus, the thymus primordium is derived from the second pharyngeal pouch endoderm, which is hoxa3-negative, suggesting that a different mechanism regulates thymus formation in frogs. Unlike other species foxn1 is not detected in the epithelium of the pharyngeal pouch in Xenopus, rather, its expression is initiated as thymic epithelial cell starts to differentiate and express MHC class II molecules. Using transplantation experiments we show that while neural crest cells populate the thymus primordia, they are not required for the specification and initial development of this organ or for T-cell differentiation in frogs. CONCLUSIONS: These studies provide novel information on early thymus development in Xenopus, and highlight a number of features that distinguish Xenopus from other organisms.

PubMed ID: 23172757
PMC ID: PMC3640628
Article link: Dev Dyn
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: ctse foxn1 gcm2 hoxa3 myh6 rag1 sox10 tec tp63 uqcc6
Antibodies: Tp63 Ab1

Article Images: [+] show captions
References [+] :
Blackburn, The nu gene acts cell-autonomously and is required for differentiation of thymic epithelial progenitors. 1996, Pubmed