Epoxide resin 618

The antennae used for Transmission electron microscopy (TEM) were excised and prefixed for 2 days with paraformaldehyde (4%) and glutaraldehyde (2.5%) in 0.1 M phosphate buffered saline (PBS, pH 7.2), then postfixed for 1 h with 1% OsO₄ in 0.1 M PBS (pH 7.2), and followed by dehydration in an ethanol series solutions (30, 50, 70, 80, 90, 95–100%) for 3 min each. After being dehydrated with pure acetone three times for 10 min each, the samples were embedded in Epoxide resin 618 through mixtures of 2: 1, 1: 1, 1: 2 of acetone and Epoxide resin 618 (Serva, Heidelberg, Germany) and then kept in pure Epoxide resin 618 overnight. Polymerization was accomplished with heating from 30 to 60°C (5°C/6 h), at 60°C for 48 h in tightly closed gelatin capsules filled completely with the resin monomer. Ultrathin sections were cut with a diamond knife (Diatome, Bienne, Switzerland) on a Leica EM UC6 microtome (Wetzlar, Germany) and then mounted on Formvar-coated grids. The sections were observed on a HITACHI H-7500 TEM (Hitachi, Tokyo, Japan). Pictures were only adjusted for brightness and contrast.