The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye

Abstract

The projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which one eye is of reduced size while the other is normal). In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.

Retinal Afferent and Efferent Connections in Congenitally Monophthalmic Chicks

“…This re sult is comparable to early eye enucleation in hamsters [Woo et al, 1985], rats [Lund et al, 1973] and mice [Godemet et al, 1980], where an expanded projection to the ipsilateral superior colliculus has been noted. Recently, in a similar study to that of Raffin and Repérant [1975], , using the tracer rhodamine iso thiocyanate (R1TC), reported that ipsilat eral fibres were absent in the late embryo.…”

Migration of phagocytotic cells and development of the murine intraretinal microglial network: An in vivo study using fluorescent dyes

“…The mouse retina is one of the preferred animal models to study normal histogenesis and assess cellular changes during pre-and postnatal development (Godement et al, 1980(Godement et al, , 1984Balkema and Dräger, 1990). The postnatal mouse retina contains about 80,000 ganglion cells (Jeffery, 1984(Jeffery, , 1985Jeffery and Perry, 1982), which mainly form connections with the contralateral superior colliculus (SC) and to a much lesser extent with visual centers of the accessory system (Dräger andOlsen, 1980, 1981;Jeffery, 1985;Balkema and Dräger, 1990).…”

“…The mouse visual system differs in this respect to that of the primate visual system. The basic mouse retinal cytoarchitecture, the types of RGCs (Doi et al, 1995) and the retinofugal projections to the thalamic nuclei and midbrain develop during embryogenesis (Godement et al, 1980(Godement et al, , 1984Cunningham, 1982;Jeffery and Perry, 1982;Adler, 1986). By embryonic day E13-14 retinofugal axons cross at the chiasm, invade the dorsal lateral geniculate nucleus (dLGN) at E16 and densely innervate the SC at birth (Godement et al, 1984).…”

Is Binocular Competition Essential for Layer Formation in the Lateral Geniculate Nucleus?

“…Even given this possibil ity, size alone would not explain why a limited ipsi lateral projection would not spread sufficiently to occupy all of the LGN territory available to it. Cer tainly, there is evidence that following early monocu lar enucleation ipsilateral retinocoliicular axons re main within topographically inappropriate parts of the superior colliculus even in rodents with a very lim ited ipsilateral projection [Finlay et al, 1979;Godement et al, 1980;Land and Lund, 1979;Lund et al, 1973], Presumably, in the case of the LGN certain ter ritories, such as the monocular segment, are either prescribed to receive specific retinal inputs, or other nonretinal but retinotopically organized inputs play some role in restricting retinal axons to specified LGN regions. Regardless, developmental restrictions on the potential territories retinogeniculate axons can occupy could also help to explain why the reported overall final increases in RGC number in the remain ing eye of early monocular enucleates (i.e.…”