Fgf components are expressed in the epithalamus during parapineal formation in zebrafish. (A-C) fgf8a (red) is expressed in the anterior pineal complex (white arrowheads) of foxd3:GFP/flhBAC:Kaede (green)-expressing embryos during parapineal development. A, anterior; L, left; P, posterior; R, right. (A′-C′) Optical cross sections at the level of the dashed lines in A-C, respectively. fgf8a is expressed in the ventral region of the anterior pineal complex anlage (white arrowheads). (D-F) Dorsal views of in situ hybridizations of fgf17 (blue) relative to the pineal complex (otx5, red). fgf17 is expressed in the anterior pineal complex (black arrowheads) at 24 hpf, but is almost gone by 30 and 36 hpf. Dashed line indicates plane of sectioning. (D′-F′) Cryosections at the levels of the dashed lines in D-F, respectively. fgf17 expression is evident in the region ventral to the anterior pineal complex anlage (black arrows) at 24 hpf. (G-I). Confocal projections show that fgfr4 (red) is expressed within the pineal complex anlage including the anterior portion (white arrowheads). (G′-I′) Optical cross sections at the level of the dashed lines in G-I, respectively, showing fgfr4 expresseion in the anterior pineal complex anlage where parapineal precursors are located (white arrowheads). (J-L) Dorsal views of in situ hybridization of erm (blue) relative to the pineal complex anlage (otx5; red). erm expression shows that Fgf signaling activity is high in the anterior pineal complex (white arrowheads). White dashed lines indicate the plane of sectioning. (J′-L′) Cryosections at the level of the dashed lines in J-L, respectively, of in situ hybridizations of erm. erm is detected in the anterior pineal complex anlage at all stages (black arrowheads). Scale bar: 25 μm.
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