Retinal Projections in the Cane Toad, <i>Bufo marinus</i>

Abstract

The location and extent of retinorecipient areas in the cane toad, Bufo marinus, were established by anterograde transport of cobaltic-lysine complex from the cut optic nerve. Most of the labeled optic axons travelled in the marginal optic tract, while others were in the axial optic tract, and/or the basal optic tract. Retinal projections terminated in both contralateral and ipsilateral targets. In addition to the optic tectum, the main visual center, retinorecipient areas included the suprachiasmatic nucleus, rostral visual nucleus, neuropil of Bellonci, corpus geniculatum thalamicum, ventrolateral thalamic nucleus (dorsal part), posterior thalamic neuropil, uncinate neuropil, pretectal nucleus lentiformis mesencephali and basal optic nucleus. While all of these retinorecipient areas receive optic fibers from both eyes, the ipsilateral retinal projections were observed to be generally sparser than those from the contralateral retina. A sparse optic fiber projection covers the surface of the ipsilateral optic tectum and is most prominent rostromedially and caudolaterally. The position and the extent of each of the retinorecipient areas were determined in relation to a three-dimensional coordinate system. Morphometric analysis showed that 85.3% of the retinorecipient area is in the contralateral optic tectum, 10.4% in contralateral non-tectal areas, 1.6% in the ipsilateral optic tectum and 2.7% in ipsilateral non-tectal areas. The presence of an ipsilateral tectal projection and the well defined pretectal visual neuropil complex may be related to the highly developed visual behavior and visual acuity of Bufo marinus.

Retinal Projections and Retinal Ganglion Cell Distribution Patterns in a Sturgeon <i>(Acipenser transmontanus),</i> a Non-Teleost Actinopterygian Fish

“…Except for the telencephalic projections, all retinal recipient areas were bilateral, but projections were heavier contralaterally in most target areas. The results coincide basically with those in Acipenser gülden-städti [Repérant et al, 1982], Polypterus palmas, Lepisosteus osseus [Braford and Northcutt, 1983], Lepisosteus platyrhincus [Collin and Northcutt, 1995], Amia calva [Butler and Northcutt, 1992], and Platyrhinoidis triseriata [Northcutt and Wathey, 1980], Lamperta fluviatilis [Vesselkin et al, 1980], Eptatretus burgeri [Kusunoki and Amemiya, 1983], Eptatretus stouti [Wicht and Northcutt, 1990], European Salamandridae [Salamandra salamandra, Triturus cristatus and Triturus alpestris ;Fritzsch, 1980], Ichthyophis kohtaoensis [Himstedt and Manteuffel, 1985], and Bufo marinus [Wye-Dvorak et al, 1992] in that a part of the optic nerve does not decussate at the chiasm, and reaches the ipsilateral target areas. However, Braford and Northcutt [1983] reported that projections to the accessory optic nucleus in Polypterus palmas and Lepisosteus osseus, and to the ventrolateral thalamic nucleus and superficial pretectal nucleus in Lepisosteus osseus are only contralateral.…”

“…We also compare the present data with those obtained in four species of chondrichthyans [Nagaprion brevirostris, Graeber and Ebbesson, 1972;Ginglymostoma cirratum, Luiten, 1981a, b; Rhinobatos productus, Ebbesson and Meyer, 1980; Platyrhinoidis triseriata, Northcutt and Wathey, 1980] as well as several teleost species [e.g. Vanegas and Northcutt and Wullimann, 1988;Butler and Saidel, 1991;Ito et al, 1992], lampreys [Vesselkin et al, 1980[Vesselkin et al, , 1984, hagfishes [Kusunoki and Amemiya, 1983;Wicht and Northcutt, 1990], lungfishes [Northcutt, 1977], and amphibians [Fritzsch, 1980;Fritzsch and Himstedt, 1981;Himstedt and Manteuffel, 1985;Uchiyama, 1989;Wye-Dvorak et al, 1992].…”

LacZ‐reporter mapping ofDlx5/6expression and genoarchitectural analysis of the postnatal mouse prethalamus

“…Based on comparable topology and connections, SG is the homolog of the classic sauropsidian and amphibian ventrolateral nucleus (e.g., reptiles, Bass & Northcutt, 1981; Derobert et al, 1999; Kenigfest et al, 1997; Medina & Smeets, 1992; Reiner, Zhang, & Eldred, 1996) (birds, Ehrlich & Mark, 1984a; Ehrlich & Mark, 1984b; Inzunza & Bravo, 1993; Marín et al, 2001; Norgren & Silver, 1989) (amphibians, Montgomery & Fite, 1989; Wye‐Dvorak, Straznicky, & Tóth, 1992). It accordingly was duly proposed to use this term also in birds (implicitly likewise in reptiles) to replace the previous “ventrolateral nucleus” name, which has clearcut wrong columnar connotations (Puelles, Martinez‐de‐la‐Torre, et al, 2019; Puelles et al, 2007); of course, “subgeniculate” is also columnar‐inspired—and strictly wrong, topologically, since it actually is a “pre‐pregeniculate” entity rather than “subgeniculate,” but this term is clumsy, and we thought it preferable to keep the known topographic SG name for the sake of clarity.…”

“…Based on comparable topology and connections, SG is the homolog of the classic sauropsidian and amphibian ventrolateral nucleus (e.g., reptiles, Bass & Northcutt, 1981;Derobert et al, 1999;Kenigfest et al, 1997;Medina & Smeets, 1992;Reiner, Zhang, & Eldred, 1996) (birds, Ehrlich & Mark, 1984a;Ehrlich & Mark, 1984b;Inzunza & Bravo, 1993;Marín et al, 2001;Norgren & Silver, 1989) (amphibians, Montgomery & Fite, 1989;Wye-Dvorak, Straznicky, & Tóth, 1992).…”

Gene expression analysis of developing cell groups in the pretectal region of Xenopus laevis

“…Its deeper cell layers apparently receive auditory afferents (Weber et al, 1986) and somesthetic projections from the dorsal column nuclei (Wiberg and Blomqvist, 1984). This pattern is reflected by the PcP in amphibians, which receives connections from the retina, torus semicircularis, obex region, and spinal cord (Neary and Wilczynski, 1977;Neary, 1988;Montgomery and Fite, 1989;Wye-Dvorak et al, 1992;Muñoz et al, 1997). The APt and PtN in Xenopus are thus surely homologous to the APTS multimodal complex.…”