TGF-β signaling in the brain does not fluctuate with the estrus cycle or gender and is equivalent between individuals. A.) Images depicting each stage of the estrus cycle. Vaginal swabs were stained by a Hema 3 Stat Pack. B.) Average bioluminescence for each day of the estrus cycle (n = 9). C.) Representative bioluminescence showing the consistency of reporter gene (luciferase) expression (4 females shown). D.) Average bioluminescence from 9 females imaged for 10 days. There is no significant difference between individuals. E.) Average bioluminescence from 5 males imaged for 10 days. There is no significant difference between individuals. Error bars, SEM.