Gene expression levels of D21 scaffolds cultured under normal versus low oxygen tension. Inner and outer MFCs were expanded to P3 then chondrogenically stimulated in scaffold culture under normal (21%, white bars) or low (3%, black bars) O2 in vitro for 21 days (D21). Data represents the mean ± SEM of pooled values for inner and outer MFC constructs cultured under 21% compared to those cultured under 3% oxygen tension. Expression levels were normalized to β-actin using 2-ΔCT method. * = p < 0.05 using Student’s two-tailed t-test.