Figure 2.

(A) Young's modulus of elasticity (E_C, MPa) as a function of stromal depth. Data (n = 4) were collected with a nanoconical indenter at 15-μm/s approach speed. The modulus of elasticity showed a logarithmic decrease with increasing depth (y = −1.52ln(x) + 10.49; R² = 0.86). Vertical bars indicate standard deviation. (B) E_C values from each sample (n = 4) were also collected with a nanoconical indenter at 2-μm/s approach speed. The modulus of elasticity showed logarithmic decrease with increasing depth (y = 1.75ln(x) + 11.45; R² = 0.90). Vertical bars indicate standard deviation. At the molecular level, E_C showed slight differences, ranging between 1% and 12%, between the two indentation rates used in this study; the differences increased with increasing stromal depth.