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250 μm coronal sections of CLARITY hybrids were fixed overnight in 4% PFA with 2% Glutaraldehyde in 0.1 M sodium cacodylate Buffer (pH 7.3). Samples were treated consecutively with ferrocyanide-reduced OsO4 (1% OsO4 with 1.5% tetrapotassium ferricyanide) (1 h), freshly prepared and syringe-filtered, 1% Thiocarbohydrazied (TCH) (40 min), 2% OsO4 (1 h) and 1% Uranyl Acetate (overnight), before dehydration in a graded ethanol series (50, 70, 90, 100%, 10 min each), followed by 2 × in 100% Acetonitrile (10 min each). Repeated washing with H₂O (3 × 5 min) was included between steps of staining and before dehydration. Tissue was then infiltrated with 25%, 50% and 75% EMBed (Electron Microscopy Sciences, Hatfield, PA) in Acetonitrile, followed by 100% EMBed (2 × 3 h) and finally EMBedding in pure EMBed with polymerization for 48 h at 60 oC. Serial ultrathin sections (200 nm each) were collected on conductive (carbon-coated) glass and Si wafer substrates, and visualized with a Zeiss Sigma FESEM (Zeiss Microscopy, Thornwood, NY) operated at 5–7 kV using BSE detection.