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Figure 4. Expression of bmp-4, gdf-5, and sox-9 in regenerating froglet blastema. A-C: Middle stage of a blastema. Bmp-4 expression was detectable in the distal region of the blastema (A, arrowheads). A′: Higher magnification of A. Bmp-4 was expressed in the mesenchyme beneath the epidermis. Gdf-5 expression was also observed in the region corresponding to bmp-4 expression (B, arrowheads). B′: Some signals of gdf-5 transcription were present not only beneath the epidermis but also in the interior. Sox-9 was expressed in chondrocytes (C,C′). D–F: Late stage of a blastema. Arrowheads point to several bmp-4 expressing cells (D,D′). Note the “salt and pepper” pattern characteristics of the bmp-4 signal. The accumulation of bmp-4 expressing cells was not detectable in the peripheral region of the cartilage. In the peripheral region of the cartilage, bmp-4 was expressed sparsely (D′). E: Gdf-5 expression in the late stage of blastema. E′,E′: Higher magnifications of E. In many cases, blastema consisted of some cartilage elements. The blastema expressed Gdf-5 in the boundaries of each element (E,E′, arrowheads), which expressed sox-9 (F). Gdf-5 was also expressed in the proximal cartilage (E, E′, arrows). Scale bar = 500 μm (A′,B′,C′,D′,E′,E′) and 100 μm (A–F). |
