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. 2012 Jul 17;7(7):e41095. doi: 10.1371/journal.pone.0041095

Figure 2. Expression analysis of FGFR1–4 and Sema3A.

Figure 2

(A’–J’) The subdivisions of the LMC and the MMC are identified by immunohistochemistry against FoxP1 and Isl1. Motor neurons in the LMCm are FoxP1+/Isl1+ (green dashed lines), LMCl motor neurons are FoxP1+/Isl1− (red dashed lines) and MMC motor neurons are FoxP1−/Isl1+ (cyan dashed lines). (A, B) FGFR1 is expressed by motor neurons in the LMCm, LMCl and MMC of control and FGFR2flox/flox;Olig2-Cre+ mutant embryos, respectively. (C) FGFR2 mRNA is found in motor neurons of the LMCm and subpopulations of LMCl and MMC motor neurons in control embryos. (D) Expression of Cre recombinase under the Olig2 promotor tissue-specifically ablates FGFR2 expression in motor neurons of the LMC and MMC, while in the ventricular zone FGFR2 mRNA is still detected (compare arrows in C and D). (E, F) FGFR3 mRNA is detected in motor neurons of the LMC and MMC in both control and FGFR2flox/flox;Olig2-Cre+ mutant embryos. (G, H) In situ hybridization against FGFR4 shows expression of the FGF receptor gene in the ventral horn of the spinal cord of control and FGFR2flox/flox;Olig2-Cre+ mutant embryos. (I) Sema3A is expressed by motor neurons in the LMCm, LMCl and MMC, respectively, in control embryos. (J) Sema3A is expressed by motor neurons of the LMCm, LMCl and MMC, respectively, in FGFR2flox/flox;Olig2-Cre+ mutant embryos. (K, L) Expression of FGFR2 in sensory neurons is not affected by ablation of FGFR2 by Olig2-Cre. (K’, L’) Immunohistochemistry against Isl-1/2 to illustrate sensory neurons in the DRG. (M) Quantification of expression levels reveals a significant decrease of FGFR2 in situ hybridization signal in the LMC of FGFR2flox/flox;Olig2-Cre+ mutant embryos, while expression levels of FGFR1, FGFR3 and FGFR4 in the LMC remain unchanged (pFGFR1 = 0,52; pFGFR3 = 0,45, pFGFR4 = 0,78). (N) Also in the MMC, expression levels of FGFR1, FGFR3 and FRGR4 remain unchanged upon loss of FGFR2 in motor neurons, while a significant decrease of FGFR2 in situ hybridization signal is observed in FGFR2flox/flox;Olig2-Cre+ mutant embryos when compared to control littermates (pFGFR1 = 0,95; pFGFR3 = 0,60, pFGFR4 = 0,20). Scale bar in J’ equals 45 µm for all panels.