Nicotine Delays Bone Growth Figure 5. Maternal nicotine exposure in wild-type mice. Ovulation-induced pregnant mice were mated and were given drinking water with nicotine during pregnancy. At noon on gestational day 15, the fetuses were sacrificed, and their legs were histologically investigated. A: Skeletal growth estimated by measuring the femur length (FL) and the length of the hypertrophic zone of the femur (HL). B: FL (mm), C: HL/FL (%) of E15.5 fetuses whose mothers were given drinking water with or without nicotine. Nicotine significantly decreased FL and HL/FL. doi:10.1371/journal.pone.0003945.g005 Figure 6. Maternal nicotine exposure in alpha7 nAChR-disrupted mice. A–C: FL, HL/FL, and body weight (BW) of alpha7 nAChR 2/2 and alpha7 nAChR +/+ E15.5 littermate fetuses. Alpha7 nAChR +/2 female were mated with alpha7 nAChR +/2 male, and given drinking water with or without nicotine during pregnancy. Relative FL, HL/FL, and BW were calculated, each value in mice that did not receive nicotine was regarded as equal to 1.0. Nicotine significantly reduced FL and HL/FL in alpha7 nAChR +/+ fetuses but not in alpha7 nAChR 2/2 fetuses (A,B). Nicotine did not significantly reduce BW in either genotype (C). D: Scatterplot and correlation between the FL and BW of mice with (red line) or without (black line) exposure to nicotine. In alpha7 nAChR +/+ fetus, Nicotine downwardly shifts the linear slope in alpha7 nAChR +/+ fetuses but not in alpha7 nAChR 2/ 2 fetuses. doi:10.1371/journal.pone.0003945.g006 PLoS ONE | www.plosone.org 7 December 2008 | Volume 3 | Issue 12 | e3945