Histochemical (A, C) and ELISA-based (B, D) quantification was performed for collagens and proteoglycans. With advanced age, total collagen (A) and type I collagen (B) decreased and total proteoglycan (C), and intact and cleaved versican (D) increased in both Eln+/− and WT valves (p<0.0001) (WT values reported (Krishnamurthy et al., 2011)). For all stages, Eln+/− valves demonstrated decreased type I and III collagens, as compared to WT group (B, p<0.0001). In addition, aged Eln+/− valves showed increased total proteoglycan content in both regions (C, p<0.005), possibly due to increased cleaved versican (D, p<0.0001), as compared to WT group. (* different from WT; # different from 1 mo).