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Figure 2. In situ hybridization of mRNAs of platelet-derived growth factor A (PDGF-A) and PDGF receptor (PDGFR) - alpha on skin sections of tadpoles. Sagittal sections of the body skin were prepared from tadpoles at stage 57 (A-D), early stage 58 (E-H), late stage 58 (I-L), and stage 59 (M-P). Sections A,E,I,M; B,F,J,N; C,G,K,O; and D,H,L,P are for hematoxylin and eosin (H&E) stains, Xenopus adult keratin (XAK) -C immunostains, in situ hybridization of PDGF-A mRNAs, and in situ hybridization of PDGFR- alpha mRNAs, respectively. A,E,I,M: The epidermis at stage 57 (A) was composed of apical (ap), skein (sk), and larval basal cells (lb). XAK-C-positive preadult basal cells (pab) emerged at early stage 58 (E,F) and larval basal cells disappeared at stage 59 (M). Skein cells were well developed and an outstanding population in the epidermis at stage 59 (M). Primordial secretory glands (PSGs) were well developed at early stage 58 (E) and differentiated into secretory glands (sg) at stage 59 (M). The collagen lamella (cl) was directly attached to the basement membrane at stage 57 (A). Beneath the collagen lamella, p-ct was present where fibroblasts (f) were sparsely scattered. The s-ct began to be formed beneath PSGs at early stage 58 (E), developed at late stage 58 (I), and further developed to secretory glands (sg) at stage 59 (M). B,F,J,N: There were no immunopositive cells at stage 57 (B). XAK-C-positive preadult basal cells (pab) were observed around PSGs at early stage 58 (arrows; F), and these cells spread to other regions on the basement membrane at late stage 58 (J) and 59 (N). C,G,K,O: No cells expressed PDGF-A mRNAs at stage 57 (C). PDGF-A mRNAs were detected in basal cells (arrows) around PSGs at early stage 58 (G), and these cells spread along the basement membrane at late stage 58 (K). The basal cells (pab) ceased the expression of PDGF-A mRNAs at stage 59 (O). Some of secretory glands were positive. D,H,L,P: Fibroblasts in p-ct weakly expressed PDGFR- alpha at stage 57 (D). Fibroblasts in the newly formed s-ct at early (H) and late stage 58 (L) intensively expressed the mRNAs and continued to express them intensively until stage 59 (P). Dashed lines in photographs represent the location of the basement membrane. Scale bar = 50 mu m in H (applies to A-J), in L (applies to K,L), in P (applies to M-P). |
