Bioluminescent imaging of Vegfr2 activity in failed pregnancy and Vegfr2-luc neonates. (a) Minimal signal was detected on gestational day (GD) 12 and 13. Light emission increased on GD 14 and 15; however, light emission drastically declined on GD 16, 17, and 18. This decrease in light emissions was associated with a poor pregnancy outcome, in which there were no surviving offspring. (b) Light emissions were detected in the neonates, and from PND 7 to 21, there was an 83-fold reduction in light emissions (P < 0.0001), indicating a decrease in Vegfr2 gene expression as the neonates progressed in development. The inserted graph depicts the increase in average pup weight (P < 0.0001) occurring during this period as an indicator of growth. The images are a representative group of animals imaged during this period.a,b,cmeans without a common superscript differ (P ≤ 0.05).