Following the immunoperoxidase or immunogold procedure, tissue sections were fixed for 15 min in 1.0% osmium tetroxide in 0.1 M PB, washed for 10 min in 0.1 M PB, dehydrated through a graded series of ethanols, placed into propylene oxide, and then a propylene oxide:EMBed (1:1) solution overnight. Sections were then incubated in EMBed for 2 h, embedded between two sheets of Aclar plastic, and placed in an oven for 24 h at 60 °C. Regions of amygdala were glued to plastic blocks formed in Beem capsules and ultrathin sections (75 nm) from an area just below the surface of the tissue at the tissue/plastic interface, where the penetration of antibodies is optimal were collected onto copper grids. The thin sections were counterstained with uranyl acetate and Reynolds lead citrate and examined using an FEI Tecnai 12 electron microscope (Hillsboro, OR). Immunoreactive (ir) profiles were captured using an AMT camera (Woburn, MA).