The choice between the positive and negative structures for nerve myelin.
D000818:Animals; D001001:Anura; D002462:Cell Membrane; D005990:Glycerol; D008959:Models, Neurological; D009186:Myelin Sheath / Q000166:cytology*; D009992:Osmium; D012584:Sciatic Nerve / Q000166:cytology*; D013194:Staining and Labeling; D014961:X-Ray Diffraction
D009992:Osmium; D005990:Glycerol