Fig. 3

eya1 mutants fail to initiate pomc and gsuα expression and to maintain gh and tshβ expression, whereas prl expression persists. All panels except panel E show whole-mount in situ hybridizations of eya1 mutants (lower panels) and wild-type siblings (upper panels) with probes indicated in upper right corners and at stages indicated in lower right corners of lower panels; lateral views, anterior to the left. In panels A, B, arrowheads indicate pomc-positive cells of the arcuate nucleus (diencephalon), arrows indicate pomc-positive cells of the adenohypophysis. (E) Semiquantitative RT-PCR to amplify lhβ (35 cycles) or, as control, gaph (25 cycles) transcripts from pools of wild-type, or lia/fgf3 or dog/eya1 mutant larvae at 78 hpf or 120 hpf. In lia mutants, all adenohypohyseal cells die around 30 hpf (Herzog et al., 2004b), suggesting that the residual lhβ signal is due to low level hormone gene expression in tissues outside the pituitary. Similar results were obtained for fshβ and in three independent experiments. In panel H, the border of the roof of the oral cavity (oc) is outlined by dots. Note that in the eya1 mutant, parts of the adenohypophysis, including the lactotropes, have protruded into the mouth cavity. In addition, lactotropes are dispersed throughout the entire gland, rather than being confined to the anterior domain, as in wild-type siblings (compare with Herzog et al., 2003). This suggests that Eya1 function and/or Eya-dependent cell specification is required for proper adhesion between adenohypophyseal cells and/or proper segregation of the different cell types into distinct subdomains of the gland. Scale bars are 50 μm.