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Fig. 6 Zebrafish rfx6 is expressed in pancreatic endocrine progenitors as well as in mature endocrine cells. (A) Lateral view of fluorescent wholemount in situ hybridization (WISH) performed on stage 19S embryos with an rfx6 antisense probe (arrowhead). (B) Ventral view of WISH with an rfx6 probe on 24 hpf embryos. (C-N) Lateral views of the pancreas area from embryos analyzed by double-fluorescent WISH, anterior to the left, dorsal to the top. (C) The expression domains of isl1 and sox4b are distinct. (D-F) Relative location of the hormone-expressing cells in relation to the neurod-, isl1- and sox4b-expressing cells. Hormone expression was detected by WISH using a cocktail of insulin, glucagon, somatostatin and ghrelin probes. The diagram shows the respective locations of sox4b-, isl1-, neurod-, and hormone-positive cells within the pancreatic area in a lateral view at 24 hpf. (G-I) At 18S, rfx6 and sox4b expression domains completely overlap, whereas at 24 hpf and 30 hpf sox4b is maintained only in the ventral part of rfx6 domain. (J-L) The expression pattern of rfx6 completely overlaps the pancreatic neurod expression pattern. (M,N) The isl1-expressing cells are located in the dorsal part of the rfx6 expression domain at 24 hpf and 30 hpf.