摘要:

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.

ISSN:0006-8977    

DOI:10.1159/000113344

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.

ISSN:0006-8977    

DOI:10.1159/000316299

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The world's deep oceans are home to a number of teleosts with asymmetrical or tubular eyes. These immobile eyes possess large spherical lenses and subtend a large binocular visual field directed either dorsally or rostrally. Derived from a lateral non-tubular eye, the tubular eye is comprised of a thick main retina, subserving the rostrally or dorsally directed binocular visual field, and a thin accessory retina subserving, the lateral, monocular visual field. The main retina is thought to receive a focussed image, while the accessory retina is too close to the lens for a focussed image to be received. Several species also possess retinal diverticula, which are small evaginations of differentiated retina located in the rostrolateral wall of the eye and thought to increase the visual field. In order to investigate the spatial resolving power of these retinae (main, accessory and diverticulum), the distribution of cells within the ganglion cell layer was analysed from retinal wholemounts and sectioned material in ten species representing four genera. In all species, the main retina possesses a marked increase in cell density towards a specialised retinal region (area centralis), with a centro-peripheral gradient range between 7:1 and 60:1 and a peak density range of between 30 and 55x103 cells per mm2. The accessory retinae and the transitional zone between the main and accessory retinae possess relatively low cell densities (between 1 and 10 x 103 cells per mm2) and lack an area centralis. Retinal diverticula examined in four species possess mean ganglion cell densities of between 7.2 and 109.4xl03 cells per mm2. Analyses of soma areas show that the ganglion cell layer of most species possesses cells with areas in a range of 8.0 to 15.4 μm2 in the main retina and between 15.1 and 17.4 μm2 in the accessory retina. The peak spatial resolving power of the main retina of the ten species varies from 4.1 to 9.1 cycles per degree. The positions of the retinal areae centrales relative to each species' binocular visual field are discussed in relation to what is known of feeding behaviour of these fishes in the deep-sea.

ISSN:0006-8977    

DOI:10.1159/000113345

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The world's deep oceans are home to a number of teleosts with asymmetrical or tubular eyes. These immobile eyes possess large spherical lenses and subtend a large binocular visual field directed either dorsally or rostrally. Derived from a lateral non-tubular eye, the tubular eye is comprised of a thick main retina, subserving the rostrally or dorsally directed binocular visual field, and a thin accessory retina subserving, the lateral, monocular visual field. The main retina is thought to receive a focussed image, while the accessory retina is too close to the lens for a focussed image to be received. Several species also possess retinal diverticula, which are small evaginations of differentiated retina located in the rostrolateral wall of the eye and thought to increase the visual field. In order to investigate the spatial resolving power of these retinae (main, accessory and diverticulum), the distribution of cells within the ganglion cell layer was analysed from retinal wholemounts and sectioned material in ten species representing four genera. In all species, the main retina possesses a marked increase in cell density towards a specialised retinal region (area centralis), with a centro-peripheral gradient range between 7:1 and 60:1 and a peak density range of between 30 and 55x103 cells per mm2. The accessory retinae and the transitional zone between the main and accessory retinae possess relatively low cell densities (between 1 and 10 x 103 cells per mm2) and lack an area centralis. Retinal diverticula examined in four species possess mean ganglion cell densities of between 7.2 and 109.4xl03 cells per mm2. Analyses of soma areas show that the ganglion cell layer of most species possesses cells with areas in a range of 8.0 to 15.4 μm2 in the main retina and between 15.1 and 17.4 μm2 in the accessory retina. The peak spatial resolving power of the main retina of the ten species varies from 4.1 to 9.1 cycles per degree. The positions of the retinal areae centrales relative to each species' binocular visual field are discussed in relation to what is known of feeding behaviour of these fishes in the deep-sea.

ISSN:0006-8977    

DOI:10.1159/000316300

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Anti-Zebrin II is an antibody directed against a 36kDa aldolase epitope expressed by Purkinje cells. Two patterns of Zebrin II immunolabeling have been described in the cerebellar corpus. In mammalian cerebella, the anti-Zebrin II labels longitudinal zones of Purkinje cells, whereas in teleosts, all Purkinje cells of the cerebellar corpus are Zebrin II immunopositive. An outgroup analysis is required to determine which of these distribution patterns represents the primitive condition for jawed vertebrates. The sister group of the Osteichthyans (ray-finned fishes, amphibians, and amniotes) is the Chondrichthyans (sharks, skates, and rays). In the present study the distribution of Zebrin II irnmunopositivity was examined in the Atlantic stingray and the Southern stingray. Western-blot analysis demonstrates that the Zebrin II antibody recognizes an antigen of the same molecular weight in stingrays, teleosts, and mammals. In stingrays, anti-Zebrin II immunohistochemistry reveals a staining pattern in which all Purkinje cells are immunopositive, no banding pattern or zonal compartmentation is observed. Purkinje cell axon projections to the cerebellar nucleus and the octaval nuclei are also revealed. Within the octaval nuclei, immunopositive Purkinje cell axon terminals and boutons en passant were found in the anterior, descending, and posterior nuclei. These immunopositive profiles are found throughout these nuclei, but they are most dense in the lateral and ventral portions. Except for the dorsolateralmost portion, the magnocellular nucleus does not appear to receive Purkinje cell inputs. Based on these results it is concluded that the Zebrin II distribution pattern in which all Purkinje cells of the cerebellar corpus are immunopositive is the primitive condition for jawed vertebrates.

ISSN:0006-8977    

DOI:10.1159/000113346

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000113347

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000113348

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000113349

出版商:S. Karger AG    

年代:1997

数据来源: Karger