Fundulus heteroclitus scales were chemically fixed with 2.5% glutaraldehyde, 2% formaldehyde in 0.1M cacodylate buffer (pH 7.3), then post-fixed in 4% osmium tetroxide and stained en bloc in 1% uranyl acetate. The scales were then dehydrated in a graded series of ethanol and infiltrated with Spurr’s resin. Thin sections of 70 nm were trimmed using a diamond knife and post-stained in uranyl acetate and lead citrate. This micrograph was imaged using a Phillips CM 100 transmission electron microscope at an accelerating voltage of 80 kV.