Age-related changes in MBP expression in human ears.

<p><b>A–B:</b> A thin MBP⁺ myelin layer (arrows) around the perikarya of some type I neurons in both the middle (<b>A</b>) and basal (<b>B</b>) turns of ears from middle-aged donors. The inset in <b>A</b> shows a type I neuron with an intact MBP⁺ myelin layer at higher magnification. <b>C</b>: A MBP⁺ myelin layer was not observed enveloping any neurons in a mid-modiolar section taken from a 74-year-old donor. There was also a marked loss of MBP⁺ fibers between neurons and a reduction in the number of PI⁺ glial cell nuclei, relative to the middle-aged specimens. <b>D, E:</b> Confocal images of the MBP⁺ myelin layer (arrows) around the perikarya of some type I neurons in the spiral ganglion from a 38-year-old and a 46-year-old donor. <b>F:</b> A MBP⁺ myelin layer was not observed in a mid-modiolar section taken from a 91-year-old donor. Scale bar, 12 µm in <b>C</b> (applies to <b>A–C</b>); 12 µm in <b>F</b> (applies to <b>D–F</b>).