The number of myelinated and unmyelinated fibers in the optic nerve of vertebrates

Bruesch, S. R.; Arey, Leslie B.

doi:10.1002/cne.900770310

Cited by 175 publications

(38 citation statements)

References 68 publications

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“…Using the light microscope, it has been estimated (Bruesch & Arey, 1942) that there are approximately 80,000 visual fibers in the optic nerve and tract of the pigmented rat and approximately 75,000 fibers in the optic nerve and tract of the albino rat. The majority of these fibers are myelinated, with the pigmented rat showing approximately 99070 myelination and the albino rat showing some 20% less myelination.…”

Section: The Optic Nerve and Tractmentioning

confidence: 99%

The primary visual system of the rat: A primer of its anatomy

LeVere

1978

Psychobiology

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Section: The Optic Nerve and Tractmentioning

confidence: 99%

The primary visual system of the rat: A primer of its anatomy

LeVere

1978

Psychobiology

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“…These studies [e.g. Bruesch and Arey, 1942;Lassek, 1942;and Towe, 1973] have not dem onstrated scaling to the 2/3 power of sur face area. But because these types of stud ies are scarce and problematic, further work is needed.…”

Section: Introductionmentioning

confidence: 99%

Allometry of Major CNS Divisions: Towards a Reevaluation of Somatic Brain-Body Scaling

Fox

Wilczynski²

1986

Brain Behav Evol

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For each of four rodent species, average weights for the brainstem, cerebellum, and forebrain were determined and average cross-sectional area of the cervical spinal cord (SCA) was calculated. Linear regression analyses against log body weight were performed on these data (log translated), along with data (except SCA) from the literature for insectivores and primates. Results indicate that the different CNS divisions scale by different powers of body weight in different mammals and that the rodent SCA varies by less than the 2/3 power of body weight. Based on the results, we conclude that (1) there are at least two general brain scaling factors, somatic and nonsomatic, that necessitate a more complex general allometric equation; (2) the exponent for somatic brain scaling is approximately 0.52, and (3) body surface area is not a primary determinant of brain size.

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“…22 and 48 for general accounts]. Similarly, the optic nerve fiber count provides a basic measure of relative visual capacity in different species [7] and is important as an independent check of the retinal ganglion cell count obtained by integration of the ret inal ganglion cell density map. The latter may be an overestimate if displaced amacrine cells and intraretinal association neurons, present in the ganglion cell layer in many species [23], are counted as ganglion cells.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of the Retinal Ganglion Cell Layer and Optic Nerve of the Barn Owl <i>Tyto alba</i>

Wathey

Pettigrew

1989

Brain Behav Evol

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The visual capacity of the common barn owl (Tyto alba) was studied by quantitative analysis of the retina and optic nerve. Cell counts in the ganglion cell layer of the whole-mounted retina revealed a temporal area centralis with peak cell density of 12,500 cells/mm² and a horizontal streak of high cell density extending from the area centralis into the nasal retina. Integration of the ganglion cell density map gave an estimated total of 1.4 million cells for the ganglion cell layer. Electron microscopy of a single, complete section of the optic nerve revealed a bimodal fiber diameter spectrum (modes at 0.3 and 0.9 µm; bin width = 0.2 µm), with diameters ranging from 0.15 µm (unmyelinated) to 6.05 µm (myelinated, sheath included). The total axon count for the optic nerve was estimated from sample counts to be about 680,000 axons (25% unmyelinated). Therefore, roughly half of the cells in the retinal ganglion cell layer do not send axons into the optic nerve. With certain assumptions the data predict a visual spatial acuity for barn owls on the order of 8 cycles/degree, a value similar to the known behaviorally measured acuities of masked owls (10 cycles/degree) and domestic cats (6 cycles/ degree).

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The number of myelinated and unmyelinated fibers in the optic nerve of vertebrates

Cited by 175 publications

References 68 publications

The primary visual system of the rat: A primer of its anatomy

The primary visual system of the rat: A primer of its anatomy

Allometry of Major CNS Divisions: Towards a Reevaluation of Somatic Brain-Body Scaling

Quantitative Analysis of the Retinal Ganglion Cell Layer and Optic Nerve of the Barn Owl <i>Tyto alba</i>

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