Fig. 4. Tbx1 in thymic development and palatogenesis. (A-C) Mediastinum of E18.5 TgCAGG-CreER^TM;Tbx1^flox/- embryos exposed to TM at E8.5 (A) and E9.5 (B), compared with a Tbx1^flox/- control (C). Asterisks indicate thymic lobes (absent in A). Cranial is upwards. (D,E) Histological sections of X-gal stained E12.5 Tbx1^mcm/+;R26R embryos showing the thymic primordium (Th) after exposure to TM at E8.5 (D) and E9.5 (E). Coronal sections, cranial is up. (F,G) Secondary palate in a E18.5 TgCAGG-CreER^TM;Tbx1^flox/- embryo exposed to TM at E11.5 (F, cleft palate between the arrows), compared with that of a Tbx1^flox/- control (G, normal fusion between the arrows). Cranial is upwards. Scale bars: 0.5 mm in C and G; 50 µm in E.