prox1 functions are required for proper otp1 and TH phenotypes in the hypothalamic area. Anterior is left, dorsal is up except for (B,B'), dorsal view. In (A) eyes have been removed. (A) prox1/otp1 double WISH. Double staining of prox1 (blue) and otp1 (red) mRNAs at 36 hpf stage reveals that otp1 and prox1 colocalize in the hypothalamus. (B,B') 36 hpf prox1/otp1 double WISH combined with TH immunohistochemistry. (B) A group of prox1/otp1-positive cells in the hypothalamus are also positive (B') for TH; for better orientation, some of these cells have been numbered (1–5) and indicated by black (B) and white (B') arrowheads, respectively. otp1 hypothalamic expression in (C) standard control morpholino and (D) prox1 MO injected embryos at 48 hpf. The following abbreviations are used: posterior tuberculum (PT), preoptic area (PO), standard control morpholino oligonucleotide (stdr MO). The following abbreviations are used: posterior tuberculum (PT), preoptic area (PO), pituitary (Pit), hypothalamus (Hy). Scale bars indicate 20 μm (A,B,B') or 30 μm (C,D).