Fig. 1

Inactivation of Piezo1 in chondrocytes impairs postnatal trabecular bone formation. a Representative von Kossa-stained sections of vertebral bodies from Piezo1^fl and Piezo1^Col2a1Cre littermates immediately after birth (P0), at postnatal days 7, 14 and 21 (P7, P14, P21) or at 6 weeks of age (6 W). Mineralized bone is stained in black. Scale bars: 500 µm. Bottom images show representative sections of vertebral bodies from Piezo2^Col2a1Cre and Piezo1/2^Col2a1Cre mice at postnatal day 21. b Histomorphometric quantification of the trabecular bone volume per tissue volume (BV/TV) and the trabecular number (Tb.N) in mice of different ages and genotypes, as indicated (n ≥ 3). c Representative Safranin O-stained sections of the lumbar spine showing growth plates from Piezo1^fl and Piezo1^Col2a1Cre littermates at postnatal day 7, 14 and 21. Cartilage is stained in red. Scale bar: 100 µm. d Histomorphometric quantification of the growth plate (GP) thickness in mice of different ages and genotypes, as indicated (n ≥ 5). e Histomorphometric quantification of proliferative zone (PZ) and hypertrophic zone (HZ) thickness in mice at P7 (n ≥ 5). f Representative Safranin O-stained sections of the lumbar spine in mice at P14, demonstrating the absence of trabecular bone structures below the growth plate in Piezo1^Col2a1Cre mice. Scale bar: 250 µm. g Representative sections of the lumbar spine at the age of P14 stained for TRAP activity. Scale bar: 50 µm. h Quantification of the number of TRAP-positive cells per tissue perimeter (TRAP⁺ cells/T.Pm) below the growth plate (n ≥ 4). Statistical analysis was conducted with Student’s t test comparing different genotypes for each age. *P < 0.05, **P < 0.01, ***P < 0.001