File:Mouse model thymus development 01.jpg

A new model of thymus organogenesis

A new model of thymus organogenesis. Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, or to obtain a text description, please contact npg@nature.coma | Embryonic day 9.5 (E9.5): positioning. Paired box gene 1 (Pax1)/Pax9 and fibroblast growth factor 8 (Fgf8; green) are required for pharyngeal pouch formation. Homeobox A3 (Hoxa3; red) is required for third pouch (p3) axial identity, possibly through the Pax–Eya–Six cascade. b | E11: initiation. Rudiment outgrowth begins at this stage. The Hox–Pax–Eya–Six cascade is required in the endoderm (yellow); Hoxa3 and Eya1 might also be required in neural crest cells (NCCs). c | E11.5–E12.5: outgrowth and patterning of the rudiment. Regionalization of the rudiment into thymus- and parathyroid-specific domains. This patterning actually begins at E10 with the expression of glial cells missing homologue 2 (Gcm2; red) in the third pouch, controlled at least in part by the Hox–Pax–Eya–Six cascade. High-level expression of forkhead box N1 (Foxn1; blue) begins at E11.25. Lymphoid progenitors (not shown) also begin to arrive at this time, entering the thymus through the capsule by a chemoattractive mechanism. d | E12–E13.5: separation from the pharynx and migration of the rudiment. Pax9 is required for separation from the pharynx. Migration might be controlled by Hox3 genes expressed by NCCs. Separation of the parathyroid from the thymus might be regulated by Gcm2. e | E12–birth: differentiation. Foxn1 is required for the generation of all thymic epithelial-cell (TEC) subtypes — cortical and medullary. Initial differentiation is thymocyte independent. Final differentiation requires thymocyte-derived signals, and depends on the Foxn1 amino-terminal domain (Foxn1Delta). Wnt signalling (through the regulation of Foxn1Delta) has been implicated in both autocrine- (TEC–TEC) and paracrine- (TEC–thymocyte) mediated differentiation. The NCC mesenchyme (not shown) might support growth and differentiation of TECs, possibly through fibroblast growth factors, whereas a lymphotoxin-receptor-dependent signalling pathway seems to control late-stage differentiation and maintenance of medullary TECs. Eya1, eyes absent 1 homologue; Six1, sine oculis-related homeobox 1 homologue. (text from original figure 5 legend)

Links: Thymus Development

Reference

<pubmed>15057786</pubmed>| Nat Rev Immunol.

Copyright

Reprinted by permission from Macmillan Publishers Ltd: [Nat Rev Immunol.] (Nature Reviews Immunology 4, 278-289 (April 2004) | doi:10.1038/nri1331), copyright (2004)

Cite this page: Hill, M.A. (2026, Mayıs 12) Embryology Mouse model thymus development 01.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Mouse_model_thymus_development_01.jpg

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