Changes in expression of (A) type I collagen (COL1A1), (B) type II collagen (COL2A1), (C) aggrecan (ACAN), (D) chondroadherin (CHAD), (E) cartilage intermediate layer protein (CILP), and (F) cartilage oligomeric matrix protein (COMP) from freshly isolated tissue, F; tissue explant culture, T; and isolated cells grown in monolayer culture at first, second, and third passage (p1, p2, p3) measured by RT-qPCR. Data are expressed as mean fold-change (+ SEM) relative to inner zone tissue explant culture (n=6/group). Within each zone (inner or outer), groups not sharing a letter are significantly different. *: significantly different from fresh inner (p<0.05, Bonferroni post-hoc).