Fig. 7

Exogenous IGF-1 promotes committed differentiation of resting chondrocytes under dietary restriction. a Schematic diagrams of the fate-mapping analysis of Axin2⁺ cells in the proximal tibial growth plate in Axin2Cre^ERT2;R26R^ZsGreen mice (pulsed on P23–25 and traced for 11 days). b Representative images of descendants of initially labeled Axin2⁺ cells (ZsGreen⁺ cells) in the proximal tibial growth plate in the DR + vehicle (b) and DR + rhIGF-1 (c) groups. d, e Quantification of the ZsGreen⁺ columns in the growth plate (d) and ZsGreen⁺ cells in the top 50 µm (e). DR + vehicle group (n = 12), DR + rhIGF-1 group (n = 12). f, g Representative images of in situ hybridization of Clu in the proximal tibial growth plate in the DR + vehicle (f) and DR + rhIGF-1 (g) groups. h Quantification of Clu⁺ cells in the top 50 μm. DR + vehicle group (n = 11), DR + rhIGF-1 group (n = 11). i, j Representative images of hematoxylin and eosin staining in the proximal tibial growth plate in the DR + vehicle (i) and DR + rhIGF-1 (j) groups. k–m Quantification of growth plate length (k), hypertrophic zone length (l) and column number per 100 µm width (m). P = 0.666 9 (ns) (k), P = 0.426 4 (ns) (l), **P = 0.008 4 (m). Data are presented as the mean ± SD. n, o Representative images for in situ hybridization of Ki67 and ZsGreen⁺ cells in the proximal tibial growth plate in the DR + vehicle group (n) and the DR + rhIGF-1 group (o). Arrowheads, ZsGreen⁺ cells expressing Ki67 (n, o). p Percentage of Ki67⁺ cells among ZsGreen⁺ cells in the top 50 µm. q Graphical summary of how the dynamics of chondroprogenitors change during DR and refeeding. Scale bars: 200 μm (b, c, f [left], g [left], i, j, 50 μm f [right], g [right]), 20 µm (n, o). All data are presented as the mean ± SD. Statistical significance was determined by one-way analysis of variance and Tukey’s multiple comparison test (b, f, j, r) or by unpaired two-tailed t test (k, n)