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. Author manuscript; available in PMC: 2013 Dec 27.
Published in final edited form as: Development. 2002 Jul;129(13):3033–3044. doi: 10.1242/dev.129.13.3033

Fig. 2.

Fig. 2

The 3rd pharyngeal pouches do not separate as buds to form the primordia of thymus/parathyroid. (A,B) Transverse sections showing that in wild-type embryos (A), the 3rd pouches evaginate and then separate as buds to form the primordia of thymus/parathyroid (th/pt) at around E12.5, while the 4th pouches separate to form the rudiments of the ultimobranchial bodies (ub) at the same time; however in Eya1−/− embryos (B), the primordia of thymus/parathyroid failed to form, while the rudiments of ultimobranchial bodies (ub) were formed but with a slight indentation (arrow in B). (C–F) Transverse sections showing Pax1 and Pax9 expression in the rudiments of the thymus/parathyroid and ultimobranchial bodies at E12.0 of wild-type embryos (C,E). In Eya1−/− embryos, the expression of Pax1 and Pax9 was only detected in the rudiments of ultimobranchial bodies (arrows). The absence of Pax1 and Pax9 expression in the prospective region of the thymus/parathyroid rudiments confirms the absence of these structures in Eya1−/− embryos (D,F). Dorsal is up. ph, pharynx; tr, trachea.