Fig. 2.

Embryo treatment with 0.003% PTU affects pituitary and thyroid gene expression as demonstrated by WISH. At 55 hpf, pituitary expression of tshb (see ventral views in A–C) and thyroidal expression of slc5a5 (see lateral views in D–F) does not differ between PTU-treated WT, PTU-treated casper, and nontreated casper embryos. However, by 80 hpf, expression of tshb (see ventral views in G–I) and slc5a5 (see ventral views in J–L) is markedly increased in PTU-treated larvae relative to nontreated larvae. All embryos are oriented with anterior to the left. Long arrows point to pituitary, and short arrows point to thyroid.