title: Arteries define the position of the thyroid gland during its developmental relocalisation.
abstract: During vertebrate development, the thyroid gland undergoes a unique relocalisation from its site of induction to a distant species-specific position in the cervical mesenchyme. We have analysed thyroid morphogenesis in wild-type and mutant zebrafish and mice, and find that localisation of growing thyroid tissue along the anteroposterior axis in zebrafish is linked to the development of the ventral aorta. In grafting experiments, ectopic vascular cells influence the localisation of thyroid tissue cell non-autonomously, showing that vessels provide guidance cues in zebrafish thyroid morphogenesis. In mouse thyroid development, the midline primordium bifurcates and two lobes relocalise cranially along the bilateral pair of carotid arteries. In hedgehog-deficient mice, thyroid tissue always develops along the ectopically and asymmetrically positioned carotid arteries, suggesting that, in mice (as in zebrafish), co-developing major arteries define the position of the thyroid. The similarity between zebrafish and mouse mutant phenotypes further indicates that thyroid relocalisation involves two morphogenetic phases, and that variation in the second phase accounts for species-specific differences in thyroid morphology. Moreover, the involvement of vessels in thyroid relocalisation sheds new light on the interpretation of congenital thyroid defects in humans.
authors.affiliation: Institute for Developmental Biology, University of Cologne, Gyrhofstrasse 17, Köln, Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Alt
authors.forename: Osama A
authors.initials: OA
authors.lastname: Elsalini
authors.forename: Pamela
authors.initials: P
authors.lastname: Schrumpf
authors.forename: Nele
authors.initials: N
authors.lastname: Haufs
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Lawson
authors.forename: Georg C
authors.initials: GC
authors.lastname: Schwabe
authors.forename: Stefan
authors.initials: S
authors.lastname: Mundlos
authors.forename: Annette
authors.initials: A
authors.lastname: Grüters
authors.forename: Heiko
authors.initials: H
authors.lastname: Krude
authors.forename: Klaus B
authors.initials: KB
authors.lastname: Rohr
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000196:embryology*; D002339:Carotid Arteries / Q000196:embryology*; D047108:Embryonic Development; D004730:Endothelium, Vascular / Q000196:embryology; D053823:Hedgehog Proteins / Q000235:genetics; D051379:Mice / Q000196:embryology* / Q000235:genetics; D008817:Mice, Mutant Strains; D009024:Morphogenesis / Q000235:genetics; D009154:Mutation; D013961:Thyroid Gland / Q000033:anatomy & histology / Q000098:blood supply* / Q000196:embryology*; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics
chemical_list: D053823:Hedgehog Proteins