Abstract
The fine structural arrangement of neural terminals on outer hair cell (OHC) of guinea pig was investigated by both thick and thin consecutive sectioning techniques. Specimens collected on single hole grids were observed under electron microscopes (H-700, H-1250, JEM-100C and JEOL-1000).
Complete serial sections from 89 OHCs were available for the present study. Both afferent and efferent neural terminals on each OHC varied in number from 5 to 35. Minimum and maximum values were obtained at the hook portion and at the second and third rows of the third turn respectively. As regarding the afferent nerve, numerous endings were seen in the second and third rows of the second and third turns. In contrast with afferent terminals, efferent endings showed less remarkable changes in number from the basal end to the apex, ranging from 1 to 11. OHCs in the first row possessed maximum innervation density of efferents at the upper part of the second and third turns. On the other hand, those in the second and third rows had maximum number of endings in the basal turn.
Maximum diameters of the afferent nerve terminals were measured, varying from 500 to 3300nm. Most of endings ranged in size from 600 to 1700nm.
