Fig. 1.

Comparison of structural features in chemically fixed and high-pressure frozen optic nerves imaged by FIB-SEM. All images are extracted from FIB-SEM datasets. A) Chemically fixed axons in a WT optic nerve. B) High-pressure frozen axons in a WT optic nerve. Note that axonal microtubules are better visible in the chemically fixed sample. The overall structure of mitochondria is well visible in both preparations in this imaging mode. Fine details of the cristae structure are not resolved. C) Chemically fixed axons in Plp^−/Y optic nerve. D) High-pressure frozen axons in optic nerve of a Plp^−/Y mouse. Note that PLP-deficient myelin is prone to fixation artifacts; the compact myelin ultrastructure can be appreciated only in the HPF prepared sample. Arrow heads point to My = Myelin, M = Mitochondria. Scale bars, 500 nm.