Retinal projections in the blind mole rat: a WGA—HRP tracing study of a natural degeneration

doi:10.1016/0165-3806(91)90002-Z

Developmental Brain Research

Volume 58, Issue 2, 22 February 1991, Pages 159-170

https://doi.org/10.1016/0165-3806(91)90002-Z Get rights and content

Abstract

The mole rat Spalax ehrenbergi is a fossorial rodent. Although its peripheral visual system — eye and optic nerve — is highly degenerated, it shows some sensitivity to light. However, in the usual sense, it is essentially blind. An auditory take-over of the visual lateral geniculate nucleus and at least part of the visual cortices was recently demonstrated. In order to visualize the retinal projections during ontogeny, we used an anterograde tracing technique, with monocular injection of wheat germ agglutinin-labeled horseradish peroxidase (WGA—HRP). In the newborn mole rat the retina projects to most of its normal targets as compared with seeing rodents, with bilateral projections to the suprachiasmatic nuclei, the dorsal and ventral lateral geniculate nuclei, the lateroposterior nuclei, the optic tract nuclei and the superior colliculi. During the course of ontogeny, the retinohypothalamic connection is stabilized but the main optic tract undergoes progressive degeneration. In adults, only a few retinal fibers enter the contralateral ventral lateral geniculate nucleus, the lateroposterior nucleus, the optic tract nucleus and the superior colliculus. No retinal fibers could be detected in the dorsal lateral geniculate nucleus. Thus, the retinofugal projections in the adult mole rat could explain its reduced sensitivity to light, whereas the complete degeneration of the retino-dorsal lateral geniculate nucleus projection could underlie the invasion of auditory input into this normally visual center.

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^☆: This study is part of the Ph.D thesis of G.B.

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Research reportRetinal projections in the blind mole rat: a WGA—HRP tracing study of a natural degeneration☆

Abstract

Neurosci. Res.

Neurosci. Lett.

Anim. Behav.

Neuroscience

Brain Res.

Brain Res. Bull.

Brain Res.

Dev. Brain Res.

Trends Neurosci.

Exp. Neurol.

Exp. Neurol.

Neuroscience

Brain Res. Bull.

Metabolic responses of a fossorial rodent (Spalax ehrenbergi) to simulated burrow conditions

Physiol. Zool.

The subterranean mole rat: an analysis of the subdermal eye

Soc. Neurosci. Abstr.

Auditory pathway and auditory activation of primary visual targets in the blind mole rat (Spalax ehrenbergi): I. A 2-deoxyglucose study of subcortical centers

J. Comp. Neurol.

Auditory activation of cortical visual fields in the blind mole rat

Ontogenetic degeneration of retinal projections in the blind mole rat (Spalax ehrenbergi)

Retinohypothalamic projections: correlation with onset of the adrenal rhythms in infant rats

Endocrinology

Ortogenesi parallela e degenerazione degli organi dello visto negli Spalacidi

Monitore Zool. Ital.

Steady diffuse light decreases, flashing diffuse light increases, colliculus metabolic activity: change detector?

Soc. Neurosci. Abstr.

Subcortical connections of the superior colliculus in the mustache bat, Pteronotus parnellii

J. Comp. Neurol.

Regressive events in neurogenesis

Science

Ontogeny of circadian rhythms

The primary and accessory optic systems in the golden hamster, Mesocricetus auratus

Acta Anat.

Mechanisms of structural and functional development in the thalamus: retinal projections to the auditory and somatosensory systems in normal and experimentally manipulated hamsters

Cross-modal projections in the study of central nervous system development

Research report
Retinal projections in the blind mole rat: a WGA—HRP tracing study of a natural degeneration☆