Figure 4. uantitative determination of gene expression measured in a growing post-natal mandibular condylar cartilage with real-time RT-PCR using SYBR Green chemistry and laser microdissection. The values were normalized against GAPDH. Data are the means ± SEM taken from three experiments. (A) The expression of IGF-I. IGF-I expression levels in the mandibular condylar cartilage progressively increased between 1 and 21 days old, reaching a peak at 21 days. (B) The expression of IGF-II. IGF-II expression levels started to decrease gradually immediately after birth. (C) The expression of FGF2. FGF-2 expression levels were relatively well-maintained until 35 days old. (D) The expression of TGFbeta2. TGFbeta2 expression levels peaked at 21 days, and rapidly decreased until 35 days. (E) The expression of Ihh. Ihh gene expression levels also peaked at 7 days old and rapidly decreased from 21 days old. (F) The expression of PTHrP. PTHrP gene expression levels were constant between 1 and 7 days old, and tended to decrease markedly from 21 days onward. (G) The expression of aggrecan. Aggrecan gene expression increased from 7 days old, peaked at 21 days old, and then began to decrease. (H) The expression of osteopontin. Osteopontin gene expression levels increased gradually over 7–35 days