Animals are anesthetized and perfused with normal Ringer’s solution (see protocol for Ringer's solution) containing xylocaine (0.2 mg/ml) and heparin (20 units/ml) for 2 minutes at 35°C followed by 0.15M cacodylate buffer (Product No. 18851, Ted Pella Inc.) pH 7.4 containing 2.5% glutaraldehyde (Product No: 18426, Ted Pella, Inc.)(Electron Microscopy Sciences, Hartfield, PA), 2% paraformaldehyde (Product No. 19202, Electron Microscopy Sciences) (see protocol for creating fixative solution) with 2mM calcium chloride at 35°C for 5 minutes.