Fig. 1

Histological and biochemical evaluation of the auricular cartilage proliferation model following bFGF administration. a–f: Histological staining of rabbit perichondrium tissue with hematoxylin and eosin (HE), g–l: biochemical evaluation of rabbit perichondrium tissue immunostained with anti-type-1 collagen peroxidase-conjugated antibody, m–r: biochemical evaluation of rabbit perichondrium tissue immunostained with anti-type-2 collagen peroxidase-conjugated antibody. a, g, m: pre-injection of bFGF; b, h, n: day 1 post bFGF-injection; c, i, o: day 3 post bFGF-injection; d, j, p: week 1 post bFGF-injection; e, k, q: week 2 post bFGF-injection; f, l, r: month 3 post bFGF-injection. Abbreviations: Pre, pre-injection of bFGF (control); D1, day 1 post bFGF-injection; D3, day 3 post bFGF-injection; W1, week 1 post bFGF-injection; W2, week 2 post bFGF-injection; M3, month 3 post bFGF-injection. a There were a few fibroblasts and endothelial cells in subcutaneous tissues. g Pericartilage cells shaped like fibroblasts in pericartilage located in the outer layer of cartilage that was immunostained for type 1 collagen. m Cartilage was immunohistochemically stained for type 2 collagen. One to 3 days after injection of a bFGF, mononuclear cell infiltrates mostly comprised macrophages (b, c), and volume expansion of the perichondrium layer was observed in the superficial perichondrium and the subcutaneous layer proximal to the perichondrium (h, i), but no changes in the cartilage were observed (n, o). One week after injection of bFGF, proliferation of the perichondrium cells with spindle and spider shapes (d) and thick extracellular matrix with type 1 collagen fiber were observed (j), but the cartilage was not changed (p). Two weeks after injection of bFGF, the superficial perichondrium layer and the deep neo-chondrium layer with neocartilage cells differentiated from the pericartilage cells (e), extracellular matrix with decreased type 1 collagen (j), and type 2 collagen fiber were observed (q). Three months after the injection, there were neocartilage cells with hypertrophy of the cytoplasm, and the cartilage was similar to mature tissue (f), whereas the extracellular matrix with type 1 collagen was limited in the outer layer of the neo-chondrium and abundant extracellular matrix with type 2 collagen was observed (r). The graph shows the mean thickness of the cartilage over the duration of the study. The differences in the thickness of cartilage between 1 week and 2 weeks were statistically significant, with P < 0.0001. “Reprinted with permission from (Yagishita, M. 2013. Involvement of mesenchymal tissue stem cells and aquaporin 1 in rabbit auricular cartilage regeneration from perichondrium with full reference. Journal of Kanazawa Medical University, 38, 43–52.). Copyright (2013) publication administration of Kanazawa Medical University”