Centrifugal visual system of <i>Crocodylus niloticus</i>: A hodological, histochemical, and immunocytochemical study

Médina, Monique; Repérant, J; Ward, Roger; Miceli, D.

doi:10.1002/cne.10959

Cited by 16 publications

(12 citation statements)

References 124 publications

(200 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the IOC of the Chilean Tinamou has a much more congregate organization than the IO neurons of crocodiles, which lie dispersed over a widespread area around the isthmus (Médina et al, ). In fact, the dense IOC “core” region which contains the majority of the centrifugal neurons, is somewhat reminiscent of the neognathous ION, while relatively few neurons lie scattered over a wider area like ectopic centrifugal neurons (Figure b,c).…”

Section: Discussionmentioning

confidence: 99%

“…However, the tectal fibers have not been conclusively shown to contact the IO neurons, and the putative tecto‐IO neurons have so far not been identified. The tecto‐ION neurons of pigeons can be conveniently labeled by retrograde transneuronal transport of intraocularly injected RITC (Miceli et al, ), while this has unfortunately failed both in crocodiles (Médina et al, ) as well as in preliminary experiments performed by us in the Chilean Tinamou. Possibly, very dense connections are necessary for detectable transneuronal RITC transport to occur.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The centrifugal visual system of a palaeognathous bird, the Chilean Tinamou (Nothoprocta perdicaria)

Krabichler

Vega‐Zuniga

Carrasco

et al. 2017

J of Comparative Neurology

View full text Add to dashboard Cite

The avian centrifugal visual system, which projects from the brain to the retina, has been intensively studied in several Neognathous birds that have a distinct isthmo-optic nucleus (ION). However, birds of the order Palaeognathae seem to lack a proper ION in histologically stained brain sections. We had previously reported in the palaeognathous Chilean Tinamou (Nothoprocta perdicaria) that intraocular injections of Cholera Toxin B subunit retrogradely label a considerable number of neurons, which form a diffuse isthmo-optic complex (IOC). In order to better understand how this IOC-based centrifugal visual system is organized, we have studied its major components by means of in vivo and in vitro tracing experiments. Our results show that the IOC, though structurally less organized than an ION, possesses a dense core region consisting of multipolar neurons. It receives afferents from neurons in L10a of the optic tectum, which are distributed with a wider interneuronal spacing than in Neognathae. The tecto-IOC terminals are delicate and divergent, unlike the prominent convergent tecto-ION terminals in Neognathae. The centrifugal IOC terminals in the retina are exclusively divergent, resembling the terminals from "ectopic" centrifugal neurons in Neognathae. We conclude that the Tinamou's IOC participates in a comparable general IOC-retina-TeO-IOC circuitry as the neognathous ION. However, the connections between the components are structurally different and their divergent character suggests a lower spatial resolution. Our findings call for further comparative studies in a broad range of species for advancing our understanding of the evolution, plasticity and functional roles of the avian centrifugal visual system.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The centrifugal visual system of a palaeognathous bird, the Chilean Tinamou (Nothoprocta perdicaria)

Krabichler

Vega‐Zuniga

Carrasco

et al. 2017

J of Comparative Neurology

View full text Add to dashboard Cite

show abstract

“…C–F). Because tinamous represent a “basal” avian group, their centrifugal visual system may represent the link between the well‐defined ION of most neognathous birds and the centrifugal visual system of the closest living relatives to birds, crocodiles (Müller and Reisz, ), who like the Chilean tinamou, also show a diffuse arrangement of the isthmo‐optic neurons (Médina et al, ).…”

Section: Discussionmentioning

confidence: 99%

The visual system of a Palaeognathous bird: Visual field, retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

Krabichler

Vega‐Zuniga

Morales

et al. 2014

J of Comparative Neurology

View full text Add to dashboard Cite

Most systematic studies of the avian visual system have focused on Neognathous species, leaving virtually unexplored the Palaeognathae, comprised of the flightless ratites and the South American tinamous. We investigated the visual field, the retinal topography, and the pattern of retinal and centrifugal projections in the Chilean tinamou, a small Palaeognath of the family Tinamidae. The tinamou has a panoramic visual field with a small frontal binocular overlap of 20°. The retina possesses three distinct topographic specializations: a horizontal visual streak, a dorsotemporal area, and an area centralis with a shallow fovea. The maximum ganglion cell density is 61,900/ mm(2) , comparable to Falconiformes. This would provide a maximal visual acuity of 14.0 cycles/degree, in spite of relatively small eyes. The central retinal projections generally conform to the characteristic arrangement observed in Neognathae, with well-differentiated contralateral targets and very few ipsilateral fibers. The centrifugal visual system is composed of a considerable number of multipolar centrifugal neurons, resembling the "ectopic" neurons described in Neognathae. They form a diffuse nuclear structure, which may correspond to the ancestral condition shared with other sauropsids. A notable feature is the presence of terminals in deep tectal layers 11-13. These fibers may represent either a novel retinotectal pathway or collateral branches from centrifugal neurons projecting to the retina. Both types of connections have been described in chicken embryos. Our results widen the basis for comparative studies of the vertebrate visual system, stressing the conserved character of the visual projections' pattern within the avian clade.

show abstract

“…While a similar feedback loop exists in birds and crocodiles, in these organisms the dendrites of the centrifugal neurons do not penetrate the optic tectum, and the feedback loop contains an additional mono-or polysynaptic pathway (cf. Repérant et al 1989Repérant et al , 2006Repérant et al , 2007Uchiyama 1989;Ward et al 1991;Médina et al 2004). …”

Section: Retinal Terminals (At1)mentioning

confidence: 97%

Synaptic circuitry in the retinorecipient layers of the optic tectum of the lamprey (Lampetra fluviatilis). A combined hodological, GABA and glutamate immunocytochemical study

et al. 2009

Self Cite

View full text Add to dashboard Cite

The ultrastructure of the retinorecipient layers of the lamprey optic tectum was analysed using tract tracing techniques combined with GABA and glutamate immunocytochemistry. Two types of neurons were identified; a population of large GABA-immunonegative cells, and a population of smaller, highly GABA-immunoreactive interneurons, some of whose dendrites contain synaptic vesicles (DCSV). Five types of axon terminals were identified and divided into two major categories. The first of these are GABA-immunonegative, highly glutamate-immunoreactive, contain round synaptic vesicles, make asymmetrical synaptic contacts, and can in turn be divided into AT1 and AT2 terminals. The AT1 terminals are those of the retinotectal projection. The origin of the nonretinal AT2 terminals could not be determined. AT1 and AT2 terminals establish synaptic contacts with DCSV, with dendrites of the retinopetal neurons (DRN), and with conventional dendritic (D) profiles. The terminals of the second category are GABA-immunoreactive and can similarly be divided into AT3 and AT4 terminals. The AT3 terminals contain pleiomorphic synaptic vesicles and make symmetrical synaptic contacts for the most part with glutamate-immunoreactive D profiles. The AT4 terminals contain rounded synaptic vesicles and make asymmetrical synaptic contacts with DRN, with DCSV, and with D profiles. A fifth, rarely observed category of terminals (AT5) contain both clear synaptic vesicles and a large number of dense-core vesicles. Synaptic triads involving AT1, AT2 or AT4 terminals are rare. Our findings are compared to these of previous studies of the fine structure and immunochemical properties of the retinorecipient layers of the optic tectum or superior colliculus of Gnathostomes.

show abstract

Centrifugal visual system of Crocodylus niloticus: A hodological, histochemical, and immunocytochemical study

Cited by 16 publications

References 124 publications

The centrifugal visual system of a palaeognathous bird, the Chilean Tinamou (Nothoprocta perdicaria)

The centrifugal visual system of a palaeognathous bird, the Chilean Tinamou (Nothoprocta perdicaria)

The visual system of a Palaeognathous bird: Visual field, retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

Synaptic circuitry in the retinorecipient layers of the optic tectum of the lamprey (Lampetra fluviatilis). A combined hodological, GABA and glutamate immunocytochemical study

Contact Info

Product

Resources

About