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Figure 3. Expression patterns of bmp-4, gdf-5, and sox-9 during hindlimb development. A,B: Bmp-4 expression in Xenopus st52 hindlimb bud. Section revealed that bmp-4 was expressed in both proximal and distal regions (A). Bmp-4 was also expressed in the distal region (B). C: In st54 limb bud, bmp-4 was expressed in the interdigital regions. D: The section of the st54 hindlimb bud revealed the expression in perichondrial cells surrounding the skeletal element. E: Higher magnification of the boxed region in D. F,G: In st59 hindlimb, bmp-4 was expressed in the joint region (F,G, arrows) and the perichondrium (F, arrowheads). Bmp-4 expression was detectable in the digit-joint region, that is, before the differentiation into three layers (G, arrowheads). H-L: Gdf-5 expression in the developing hindlimb bud. In st52 hindlimb bud, gdf-5 was expressed at low levels in the posterior region, which was similar to the expression of bmp-4 (H). In the st53 hindlimb bud, gdf-5 expression was detectable in the autopodium (I). Gdf-5 expression was restricted to the joint region (J). In the st58 hindlimb bud, clear signals of gdf-5 expression were detectable in the joint region (K). The section revealed that the expressions were restricted to the joint region and also slightly detectable in chondrocytes (L). M: Sox-9 was strongly expressed in chondrocytes. The sox-9 expression was detectable broadly from the distal to proximal regions. N: In the st55 hindlimb bud, sox-9 expression in the presumptive joint region was decreased (arrows). Scale bar = 200 mu m. |