A quantitative study of the effects of microphthalmia on the organisation of the primary visual system of the mouse.
The retinal projections of C57BL/Orl mice homozygous for the mutation microphthalmic-white (Miwh) were investigated by autoradiographic and HRP tracing techniques, and compared to those of heterozygous and normal mice of the same inbred strain; the anatomy of the eyes and optic nerves of the three genotypes were also examined. The eye of homozygous mutant mice is considerably reduced in size; the optic nerve shows a decrease in the number of myelinated fibres which is partially compensated by an increase in the proportion of unmyelinated axons. All primary visual centres that are labelled in normal mice receive retinal projections in mutant mice, although these centres are reduced in size in mutants. The reduction is most evident for those centres forming the thalamic relays of the retino-telencephalic pathway, to a lesser extent for the retino-collicular pathway and least of all for the retino-hypothalamic projections. These findings are compared to those obtained in naturally microphthalmic rodent species, and also to the effects of another mutation at the mi locus, maintained on a different background.
D'Agostini
E
E
Laboratoire d'Anatomie Comparée, M. N. H. N., Paris.
Herbin
M
M
Repérant
J
J
Ward
R
R
Wasowicz
M
M
D000818:Animals; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009900:Optic Nerve / Q000502:physiology*; D014793:Visual Cortex / Q000033:anatomy & histology*; D014795:Visual Pathways / Q000033:anatomy & histology*