Abstract
On the basis of light and electron microscopic observations of the cross-section, the total count of optic nerve fibers in the eastern chipmunk (Tamias Sibiricus asiaticus) was estimated to be 5.65 × 105. Almost all the fibers were myelinated and only 0.9% were unmyelinated. Axon diameters of myelinated fibers showed a skewed unimodal distribution ranging from 0.2 to 3.6 μm (mean, 0.83) with the peak at 0.6-0.7 μm. Myelin sheath thickness positively correlated with the axon diameter. In the cross-section fiber density was highest in the naso-dorsal to the central part and lowest in the temporo-ventral part. Large axons are concentrated in the temporo-ventral part of the optic nerve, corresponding to the localisation of large ganglion cells in temporal crescent of the retina. A gross retinotopic organisation was verified among the optic nerve fibers in the cross-section after localised lesions by laser beam in the nasal and temporal periphery. However, when the retinal lesion was made in or around the central high density area, a non-retinotopic arrangement of the optic nerve fibers was suggested.
Original language | English |
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Pages (from-to) | 1891-1901 |
Number of pages | 11 |
Journal | Vision Research |
Volume | 27 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1987 |
Keywords
- (Tamias sibiricus asiaticus)
- Axon diameter
- Eastern chipmunk
- Optic nerve
- Retinotopy
- Total fiber count
ASJC Scopus subject areas
- Ophthalmology
- Sensory Systems