In situ expression analysis of transcripts possibly involved during cartilage differentiation. A-J: Expression of five cartilage genes at 3 days postamputation (dpa; A-E) and 5 dpa (F-J). Arrowheads represent the site of amputation. The rug1, prohibitin, ENTPD5. and osterix are expressed in a region adjacent to the blastema (asterisks). The prohibitin and ENTPD5 show additional expression in a more proximal region of the regenerates. The expression of biglycan is seen only in the proximal region. A slight staining of biglycan in the blastema seems to be a background signal. K-R: Expression of cartilage genes during the embryonic and larval development. K-N: At stage 39, the expression of the four genes, except biglycan, is observed in the developing cartilage of branchial arches (arrowheads). O-R: At stage 39, the expression in the fin primordia begins in the basal region of median fin fold (arrows), at which location the cartilage of hemirays (lepidotrichium) is differentiating from the osteoblasts.

In situ expression of transcripts that may have a role in blastema and basal wound epidermis. A-I: Three genes, tsp2, sppl2, and rug2, are expressed in the basal epidermal layer at 3 days postamputation (dpa; A-F) and 10 dpa (G-I). D-F: The localization of the transcripts in the basal wound epidermis was confirmed in the cross-sections of stained fins (arrows). J-U: Expression of the blastema genes beta ig-h3 rug3, neurocan, and angptl2, at 3 dpa (J-Q) and 10 dpa (R-U). N-Q: No expression in the basal epidermal layer was seen in the cross-sections of the respective samples. Only the beta ig-h3 expression is retained in fins at 10 dpa (R), but only a faint expression was detected for rug3, neurocan, and angptl2 at that time. Arrowheads represent the site of amputation.

Embryonic and larval expression of transcripts up-regulated in the blastema or basal wound epidermis. A-I: Expression of the basal wound epidermis genes tsp2 (A-C), sppl2 (D-F), and rug2 (G-I). At stage 28 of embryonic development (A,D,G), these genes begin to be expressed in the basal region of the median fin fold (arrowheads). Until stage 39, a strong expression is seen in the periphery of the pectoral fins (pf, pectoral fins; B, E, H) and in the whole region of the median fin fold (arrowheads in C, F, I). J-L: Expression of blastema genes. J: At stage 28, the expression of neurocan is seen in cells of the nervous systems (arrows). The beta ig-h3 is expressed in the somites and ubiquitous cells.