Analysis of the retinas and optic nerves of achiasmatic belgian sheepdogs

Dale Hogan, Robert Williams

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

An autosomal recessive mutation carried in a family of black Belgian sheepdogs eliminates the optic chiasm—all retinal ganglion cell axons extend directly into the ipsilateral optic tract. One key issue we are trying to resolve is whether the retina or the chiasm is the principal site of mutant gene action. In this study, we have examined retinas of mutants to discover any associated changes in retinal structure. Retinas of mutant animals are relatively normal. Inner and outer nuclear layers are qualitatively indistinguishable from those of normal dogs. The principal difference is that the area centralis of mutants is smaller and has a lower peak ganglion cell density than that of normal dogs (8,100 vs. 10,500/mm2, P < 0.05). This mutant phenotype is similar to that seen in retinas of Siamese cats and albino ferrets. Beyond area centralis, the central‐to‐peripheral gradient in ganglion cell density is normal in mutants. The size of the optic nerves, density of axons, and total number of axons do not differ between mutant and normal dogs. One of three mutant dogs had a small abnormal optic chiasm. Retrograde labeling of ganglion cells demonstrated that the residual crossed projection originated from cells in a widespread region in nasal retina and not solely from the peripheral nasal region, as might be expected of an anti‐albino. Although our analysis does not rule out the retina as a site of mutant gene action, the modest differences between mutant and normal retinas suggest that the mutation either acts outside the retina or exerts a highly specific effect on ganglion cell trajectories alone. © 1995 Wiley‐Liss, Inc.

Original languageEnglish (US)
Pages (from-to)367-380
Number of pages14
JournalJournal of Comparative Neurology
Volume352
Issue number3
DOIs
StatePublished - Jan 1 1995

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Optic Nerve
Retina
Ganglia
Dogs
Axons
Nose
Cell Count
Optic Chiasm
Ferrets
Mutation
Retinal Ganglion Cells
Genes
Cats
Phenotype

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

Analysis of the retinas and optic nerves of achiasmatic belgian sheepdogs. / Hogan, Dale; Williams, Robert.

In: Journal of Comparative Neurology, Vol. 352, No. 3, 01.01.1995, p. 367-380.

Research output: Contribution to journalArticle

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