Figure 2

Electron micrographs of myelinated axons in white matter below STG taken from two human brain samples case 1 and case 2. (A): Low magnification electron micrograph shows numerous myelinated axons of varying sizes in case 1. (B, C) High magnification EM demonstrates ultrastructural details of myelinated axons in cross and sagittal orientation. Note fine structure of microtubules and other subcellular organelles can be identified. The compactness of myelin sheaths differs among axons; bars = 0.5 μm. (D) Higher magnification EM of thick compact myelinated axon indicated in (C) by asterisk. Layers of myelin sheath can be clearly identified and counted. Axon diameter is defined by double arrow pointing to axoplasmic membranes labeled as a, the diameter of the myelinated fiber is defined by a double arrow pointed to the out layers of myelin sheath labeled as A; g-ratio = a/A. bar = 0.1 μm. (E) Low magnification EM shows myelinated axons and a few oligodendrocytes cell bodies in case 2. Note space between axon profiles is smaller compared to (A) indicating better structural preservation; bar = 2 μm. (F, G) High magnification EM showing some myelinated axons of varying sizes and myelin thickness. Note microtubules and neurofilaments can be clearly identified within axons; bar = 0.5 μm.