Right-left asymmetry of myelin development in epiretinal portion of rabbit optic nerve

Abstract

DOMINANCE is the priority or preferential activity of one member of any bilateral pair of structures in the body. The phenomenon of dominant hand, foot and eye for example is well known in humans and this basic sidedness is thought to be cerebral in origin. Based on experiments on audiogenie seizures evidence has been produced for an asymmetry of cerebral function in certain inbred strains of mice¹. In other animal species dogs are known to have preference of paw, and right–left eye dominance in the visual cortex of cats has been demonstrated². Various theories have emerged to explain ocular dominance^3,4. It is generally accepted that this is not associated with significant structural differences between the two halves of the brain⁵. Apart from morphological evidence for left–right asymmetries in temporal lobes of speech regions⁶, very little evidence for anatomical differences has been produced in humans or other animals. The rabbit retina is unique in having bundles of myelinated nerve fibres extending equatorially from the optic disk, which are unmyelinated at birth but in which myelination begins at 9–10 days of age⁷. I present here results which indicate that the sequence of myelination is asymmetrical between the right and left eyes, one being dominant.