Correlation of gene expression and THs in the GD20 fetus. A, Camk4 expression in the fetal forebrain is well correlated to serum T4. B, Thrb is not as linearly related to graded reductions in serum T4. For both Camk4 and Thrb, percent change in gene expression is also linearly correlated to percent change in fetal brain T4, but with higher support values than those observed for serum. Gene expression is also highly correlated to changes in brain T3 (E, F) in the fetus. Error bars represent 6 SEM for both the x and y values, and R2 values are noted on each panel.