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, D) indicate the thyroid primordium. The arrow in D indicates forebrain hypoplasia in Rbpj -/-mutants. Fb, forebrain; Ot, otic vesicle. Figure 4: Forebrain hypoplasia in Rbpj L/L

L. Rbpj and R. ,

, Whole-mount in situ hybridisation analysis of Nkx2.1, Shh, Fgf10 and BMP7 in embryos of the indicated genotype and stage (A D). (A), Nkx2.1 mRNA was absent in the AH of the mutant embryo (arrowhead). (B), Expression of Shh was variable in mutant embryos are from the same litter. Asterisk indicates hypoplasic telencephalic vesicle, CreER T2 tamoxifen-treated embryos at E7.75

, In the mutant embryo

, CreER T2 Fgf10 expression was expanded in a more anterior region of the hypothalamus (large bracket). (D), Bmp7 expression in the telencephalic vesicles (bracket). AH, anterior hypothalamus

H. , H. Ot, and . Ov,

T. and T. Vesicle,

, Figure 5: Brain and cranial bone defects were observed in Shh +/-;Rbpj +/-mutant embryos (A-C) Hematoxylin and eosin staining of frontal section through E18.5 heads. Note the remnant connection (yellow arrow) between the anterior part of the pituitary gland and the oral ectoderm (OE)

, Ventral views of cranial preparations of E18.5 embryos stained with Alizarin red and Alcian blue for bone and cartilage, respectively. Mandibles have been removed for visualisation. (E) White arrow indicates the persistent buccohypophyseal canal at the level of the midline in Shh +/-mutants

, Asterisk indicates the enlarged canal in Shh +

+. Rbpj, , vol.3

H. Oc,

P. and P. Gland,

;. Ps, . Px, and . Pharynx,