VGLUT1 and VGLUT2 mRNA expression in auditory cortex. VGLUT1 mRNA (A – C) is expressed in neurons spanning layers II – VI. VGLUT2 mRNA (E – G) expression is strongest in layer IIIb, weaker in layers II, IIIa, and IV, and very low or absent in layers V and VI. Paired panels (C – D) and (G – H) are images of the same sections through A1, dual-labeled for mRNA by in situ hybridization (C, G) and fluorescent Nissl stain (D, H) to show laminar details. Scale bars = 500 um.