Cre is selectively expressed in PV interneurons in PV-Cre mice. A, Confocal image showing immunostaining for PV (left) and tdTomato (middle) in PV-Cre::Ai14 mice. Right, Merge image. Arrows indicate cells double-labeled for PV and tdTomato. Arrowhead indicates a cell positive for PV but negative for tdTomato. Scale bars, 50 μm. pyr, Stratum pyramidale. B, Bar chart indicating the average percentage of double-labeled cells in PV-Cre::Ai14 mice within the whole PV (green) or tdTomato (red) populations. Counting was performed in 15 slices from 2 animals; n = 443 total tdTomato+ cells. Error bars indicate SEM.