Biomedical subjects

G Pinganaud

Publications and source records attributed to G Pinganaud.

22 records · Page 2Linked to original sources

PubMed1983

[Retinotopic projections of the trout (Salmo gairdneri)].

The retinotopic organization of the thalamic and tectal and visual centres was studied by Fink and Heimer method and radioautography. Quadratic lesions were achieved in the right retina of 21 adult trouts and 23 six month old specimens. Fourteen animals (adults) were kept alive for 20 to 25 days after operation, in running water at 13 degrees C and prepared for the Fink technique. In the remaining 7 adults and in the 23 six month specimens, we injected, 48 hours after the lesion, respectively, 2,5 microCi (in 20 microliters) and 0,5 microCi (in 1 microliter) of 14 C proline into the operated eye. The brains were prepared for radioautography. Results show that the thalamic pathways is not correlated with a peculiar quadrant. Nevertheless the temporo dorsal hemiretina sends the more numerous projections at this level. A topographic parallelism exists between retino-geniculate and retino-tectal projections. At the tectal level our data are somewhat at variance with those of electrophysiological mapping, since quadratic projections show a partial overlapping. In the optic tract, the fibres from every quadrant follow always the same pathway.

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PubMed1980

[Development of the trout visual system (Salmo irideus) (author's transl)].

The organization of the primary visual system of the larval trout (Salmo irideus) was studied at different stages of development: 5 days before hatching, 1 and 2 months post-hatching, by Fink and Heimer's method and radioautography. After ablation of the right retina or injection of 14C Proline (0,05 microCi in 0,5 microliter) in the right eye, animals were kept at 13 degrees C for 6 hours to 7 days and fixed according to the technic used. We also stained transverse sections of larval stages (14 days before hatching to hatching stage) with Bodian's method. The results show that the retino-tectal fibers are precocious. They are present five days before hatching. The retino-thalamic projections appear at hatching. The geniculate nucleus has a mesencephalic origin. The radioautograms show this structure at hatching. The optic tectum differentiates progressively latero-medially and from the anterior level to the posterior level. Among the 3 correspondent optic tectal layers of the adult (superficial, intermediate and deep), the second is present at hatching while the two others appear progressively between one and two months. A comparison of the fish brain with that of other vertebrates is difficult. We try to discuss some problems of homology (geniculate nucleus, pretectum, accessory optic centre).

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PubMed1979

The visual system of the trout Salmo irideus Gibb. A degeneration and radioautographic study.

The organization of the primary visual system of the trout (Salmo irideus Gibb.) was studied by Fink-Heimer methods and radioautography. In addition to normal fiber, Nissl and Golgi staining techniques, we carried out total ablation of the retina on the right side on 16 animals which survived post-operatively at 13 degrees C for 9 to 31 days. The brains were cut at 35 micrometer and then stained by the Fink-Heimer techniques. Furthermore, we injected 20 microliter (2 microCi) of 14C proline into the right eye of 8 trouts which were then fixed between 24 and 72 hours after the injection, and then prepared for radioautography. The primary visual system projections are entirely contralateral. The optic tract is divided into three bundles which pass into tectal layers 2, 4 and 6. In the trout, a very obvious deep optic layer is present which extends throughout the length of the medial part of the tectum. In addition to the accessory optic tract and to a projection at the level of the preoptic area, the trout possesses a well-developed thalamic visual system composed of a ribboned geniculate nucleus and two medial thalamic visual centres fed by the retinothalamic pathways as well as a small retinal target located in the lateral thalamus. The pretectum receives only a few small sparse retinal projections. An interpretation of the trout visual system as the whole is discussed.

Animals↗

PubMedDate not supplied

[Architecture of the pathways and primary optical centers in trout (Salmo irideus Gibb.)].

The retinal projections of the Trout were examined on fifteen adult specimens (eighteen months) unilaterally enucleated. After a post-operative survival period of six to 31 days, the degenerating fibers were stained with Fink-Heimer technique. The optic tract is entirely crossed. At the rostral end of the thalamus a first fascicle diverges which runs to aventral thalamic center and to a dorsal thalamic center. The latter extends caudally as a pretectal center. The second fascicle is a retinogeniculo-tectal pathway which borders the geniculate body and enters the external tectal layer. The corpus geniculatum is large, well laminated and contains terminal degeneration. The main part of the optic tract includes three fascicles. Each of them sends fibers to all three tectal layers.

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