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Figure 3 | BMC Developmental Biology

Figure 3

From: Fgfr1 signalling in the development of a sexually selected trait in vertebrates, the sword of swordtail fish

Figure 3

Expression of fgfr1 and msxC in the developing sword. X. helleri fgfr1 is up-regulated during sword development. When maturation is induced by exogenous testosterone, fgfr1 is up-regulated in the ventral-most caudal fin rays in developing swords at 5 and 10 days of treatment (dt)(A, F). Weaker expression of fgfr1 can also be detected in non-sword rays (A, D, E). fgfr1 is not up-regulated in untreated control fins (C). fgfr1 expression overlaps with msxC, which is also up-regulated in developing sword rays ([23], B and I). In later stages of treatment, up-regulation of both genes in the distal part of the dorsal-most rays is observed in some individuals (G), which may develop a small "upper sword" ([20]). Like fgfr1, msxC expression is also detected in non-sword rays (G, H). When maturation is induced by exogenous testosterone in the platyfish, X. maculatus fgfr1 and msxC are similarly expressed in all caudal fin rays after 5 dt (J and K). The expression levels are comparable to untreated fish (L). After 10 dt fgfr1 is more strongly expressed in the ventral-most fin-rays (O) compared to other rays (M, N), which may correspond to the formation of a small ventral swordlet [20, 22]. White arrowheads indicate gene expression. (X. helleri: n = 10 for every stage and probe; X. maculatus: 5 dt: n = 5; 10 dt and controls: n = 3; scale bars: 200 μm)

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