Relative liver weight (RLW) of male C57BL/6 mice orally gavaged with sesame oil vehicle or 30 µg/kg TCDD every 4 days for 28 days. Data points represent the average of at least 3 individual mice ± standard error of the mean. Statistical significance (*p ≤ 0.05) between vehicle and TCDD was determined using a two-way ANOVA analysis followed by Sidak’s multiple comparison test. JTK_CYCLE determined RLW in control animals exhibited daily oscillations (# BH q ≤ 0.1), while RLW rhythmicity was not detected in TCDD-treated mice. Data are double-plotted along the x-axis for better visualization of rhythmicity.