Fig. 4-S1
Parapineal cells impose left habenula character on right dorsal habenula neurons.
(A–D) Parapineal cells from an H2B:RFP mRNA-injected Tg(foxD3:GFP);(flh:eGFP) donor embryo transplanted to the right side of a Tg(foxD3:GFP);(flh:eGFP) recipient at 32 hpf send projections to the habenula at 50 hpf (arrows in A and C), whereas transplanted pineal cells (B, D) do not (but reintegrate into the pineal and/or locate to the midline). Scale bars 25 µm. (A’–D’) By 4 dpf, the right habenula adjacent to the transplanted parapineal cells acquires a left habenula phenotype, as shown by increase in kctd12.1 mRNA expression (A’) and anterogradely labelled efferent habenula-IPN projections (dorsal and lateral views) (C’). Note the innervation of dorsal IPN (dIPN) by both, the left and right habenula (lHb, rHb) in parapineal-transplanted larvae. Larvae with pineal cell transplants exhibit a wild-type habenular phenotype at four dpf (B’,D’).