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  • 1
    Electronic Resource
    Electronic Resource
    The onset of synaptogenesis in rat temporal cortex (1975)
    Springer
    Anatomy and embryology 148 (1975), S. 73-87 
    Details
    ISSN: 1432-0568
    Keywords: Rat ; Temporal cortex ; Synaptogenesis ; Retzius-Cajal cells ; Poly morphous cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The onset of synaptogenesis was studied in the temporal cortex of rat fetuses whose age ranged between 15 and 19 days of gestation. First synapses were found at a surprisingly early stage of cortical development: on day 16. These contacts showed relatively few vesicles and very inconspicuous membrane-thickenings. They were located in the marginal layer, above as well as below the narrow band formed by the newly arrived first neuroblasts of the prospective cortical plate. The postsynaptic structures were probably dendrites of the horizontally or obliquely orientated neurons scattered throughout the marginal layer (such neurons were seen even within the cell-dense band). On day 17, the cortical plate separated the differentiated cells definitely into a superficial and a deep population. As on the following days, synapses were found above and below the cortical plate but not within it. In addition to contacts showing the same features as those described on day 16, there were already synapses with numerous vesicles and clearly asymmetric membrane thickenings. On days 18 and 19 the borders of the cortical plate became more clear-cut. The well-differentiated neurons situated above and below this plate could now be identified as Retzius-Cajal cells of the prospective molecular layer and as polymorphous cells of the layer VI b respectively. The presence of axo-somatic contacts on these neurons provided direct evidence that both cell types are targets for synapses. Desmosome-like junctions were found even in the youngest fetuses studied. Their roughly symmetric membrane thickenings were clearly more conspicuous than those of earliest synapses. Desmosome-like junctions occurred very frequently between structures which subsequently were never seen to become synaptically linked. During the entire period studied, numerous coated vesicles fused with cell membranes were noted. Such “open” vesicles were seen on neurons (sometimes in the immediate vicinity of synapses) but also on non-nervous, extracortical as well as intracortical structures. Thus there does not seem to be a specific relationship between desmosome-like junctions and coated vesicles on the one hand and synapse formation on the other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315564
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  • 2
    Electronic Resource
    Electronic Resource
    Cinétique des processus de dégénérescence axonique dans le système nerveux central: Étude expérimentale à court terme dans le corps calleux chez le rat (1974)
    Springer
    Acta neuropathologica 29 (1974), S. 311-323 
    Details
    ISSN: 1432-0533
    Keywords: Axonal Degeneration ; Corpus Callosum ; Kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Transection of the corpus callosum was carried out on 20 adult rats and the spatio-temporal pattern of the degeneration process was studied on the 2nd, 8th, 15th and 30th days following the operation for 3 segments of the axon, from the point of severance to the cerebral cortex. In the distal segment of the severed axons degeneration set in simultaneously at the point of severance and in the terminal boutons. Anterograde progression of the process may exist, at least over a short distance. There is definite, though perhaps limited retrograde progression starting from the terminal boutons. The conditions under which the total length of the fibre is affected, kinetically speaking, are the subject of a discussion. At the stages chosen for examination, only a part of the proximal endings are affected by Wallerian degeneration. At the same periods the proximal segment of the axons leading in the opposite direction in the corpus callosum, still appears intact, although the corresponding cellular bodies are in an advanced state of chromatolysis. During the degeneration of the distal segments the myelin sheath remains apparently normal, whereas the axoplasm is in an advanced state of desintegration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685484
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  • 3
    Electronic Resource
    Electronic Resource
    Désafférentation expérimentale de l'écorce cérébrale: Étude par la méthode de Golgi-Cox en microscopies optique et électronique (1972)
    Springer
    Acta neuropathologica 22 (1972), S. 245-256 
    Details
    ISSN: 1432-0533
    Keywords: Cat Cerebral Cortex ; Deafferentation ; Golgi-Cox ; Light and Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The auditive cortical area of the cat, which had been deafferentated from the medial geniculate body by electrolytic lesion and impregnated by the Golgi-Cox method, was studied by light and electron microscopy at various intervals after the intervention and compared with normal animals. In light microscopy the gradual breakdown of the dendrites, followed by that of cellular body of the majority of the impregnated neurons was observed. On the 25th day after the intervention the only visible cellular elements were neuroglial. In the thin sections the impregnated neurons revealed similar modifications to those mentioned above and coexisted with the unimpregnated neurons and the neuroglial elements. In electron microscopy, the impregnated neurons appeared dark and homogenous in the normal animal. The disappearance of the endoplasmic organisation contrasted with the conservation of the nucleus. After deafferentation the cytoplasm revealed an ever increasing loss of substance in the form of rounded shapes corresponding approximately to the size of the metallic deposits. On the basis of previous results, where the deafferentation was studied by electron microscopy without metallic impregnation, these results can be interpreted as expressing, on the part of the deafferented neurons, the gradual loss of affinity for the mercury. However this fact does not exclude the possibility of a certain number of neurons, already impregnated by the mercury actually desintegrating after the first 3 weeks following the intervention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00684527
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  • 4
    Electronic Resource
    Electronic Resource
    Dégénérescence Wallérienne expérimentale dans les noyaux vestibulaires: Etude en microscopies optique et électronique après imprégnation argentique (1974)
    Springer
    Acta neuropathologica 27 (1974), S. 119-129 
    Details
    ISSN: 1432-0533
    Keywords: Axonal Degeneration ; Vestibular Nuclei ; Silver Impregnation ; Light and Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study of Wallerian degeneration in the vestibular fibres was carried out on the adult cat after electrolytic destruction of the nerve at its point of entry in the brain stem. Histological observation was restricted to the ventral part of the lateral vestibular nucleus and the adjacent portion of the descending vestibular nucleus: — the classic insertion points of primary afferent fibres —. Once embedded in paraffin wax and stained by ammoniacal silver (following Nauta and Gygax, 1951), the sections were studied conjointly by light and electron microscopy. Ultrastructural analysis revealed the high density of the silver deposit inside the neurons and its relative rareness in the terminal boutons. As a result the latter were basely identifiable by light microscopy, in spite of their being larger than the preterminal segment of the neuron. These results are compared with those obtained by methods which have undergone similar stringent tests, such as those of Fink and Heimer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687162
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  • 5
    Electronic Resource
    Electronic Resource
    La réaction de Marchi: Aspects ultrastructuraux (1975)
    Springer
    Acta neuropathologica 32 (1975), S. 199-207 
    Details
    ISSN: 1432-0533
    Keywords: Marchi Reaction ; Secondary Demyelination ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A secondary demyelination process was brought about in the optic tract by unilateral enucleation of 10 adult rats which were sacrificed at 8, 15, 20, 30 and 45 days respectively, after the intervention. The Marchi reaction, which is identifiable by the presence of granular bodies, is positive at all stages, but tends to lessen towards the 45th day. The granular bodies are inside the disintegrating myelin sheath, and gradually fill the space made available by the degenerate axoplasm. The granular bodies are at first bulky and compact before breaking up and disappearing. The remains of the myelin sheath are then resorbed. Satellite cells occur from the 15th day onwards. The interest of the Marchi reaction for the tracing of nervous pathways is confirmed by these findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696569
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  • 6
    Electronic Resource
    Electronic Resource
    Etude quantitative du marquage radioautographique dans le système nerveux du rat II. Caractéristiques finales dans le cerveau de l'animal adulte: Lois d'interprétation et concept de chronoarchitectonie corticale (1975)
    Springer
    Experimental brain research 22 (1975), S. 37-56 
    Details
    ISSN: 1432-1106
    Keywords: Quantitative radioautography ; Chronoarchitectony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Une étude radioautographique quantitative a été pratiquée sur des neurones de rats adultes qui avaient été marqués prénatalement avec de la thymidine tritiée. Elle aboutit à établir des histogrammes globaux de formes complexes, qui résultent en réalité de l'addition d'histogrammes primitifs poissonniens. Basées sur le calcul des probabilités, des règles théoriques ont été établies. A partir de certaines caractéristiques de l'histogramme final relevé dans une région définie, il devient ainsi possible par cette méthode de connaître le nombre et l'importance des générations cellulaires qui la constitue (chronologie). En outre, en partant de l'étude graphique du pourcentage des cellules marquées et de la moyenne des grains, les caractéristiques de stratification de la population neuronique peuvent être définies (architectonie). Ces notions sont réunies dans un nouveau concept : la chronoarchitectonie. L'application de ce concept au néocortex montre qu'il existe toujours une profonde interpénétration des différentes générations cellulaires au niveau d'une couche déterminée. D'autre part, la production neuronique est un phénomène de type continu, qui est sans correspondance avec les différentes couches corticales.
    Notes: Summary In this work a statistical study is made of the final outcome of the quantification of the nerve cell labelling in the adult, after prenatal injection of tritiated thymidine. This outcome is presented in the form of histograms which are the super-position of elementary Poisson distributions. A theoretical model, based on Probability theory, has been developed explaining the experimental outcome. Studying the final histograms of a defined region, according to this model, we can find out the number and the importance of the constitutive cell generations (chronology). From the graphic study of the percentage of labelled cells and that of the average of grains, the characteristics of the stratification of the neuronic populations (architectony) can be defined. All these notions have been gathered into a new concept: chronoarchitectony. This concept has also been applied to the neocortex. The results show that there is a strong interpenetration of the different cell generations in a given layer. The cortical neuronic production is a continuous phenomenon and there is no correspondence with the discontinuity of the cortical layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235410
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  • 7
    Electronic Resource
    Electronic Resource
    Maturation postnatale du tractus optique chez le Rat: Identification et quantification de la névroglie sur radio-autographies (1973)
    Springer
    Experimental brain research 16 (1973), S. 466-475 
    Details
    ISSN: 1432-1106
    Keywords: Neuroglia ; Radio-autography ; Myelination ; Optic tract ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Resume Une étude, basée sur l'identification et la quantification histologique des cellules névrogliques, a été entreprise dans le tractus optique du Rat sur radio-autographies après injection de thymidine tritiée. Ce bilan a été effectué entre 2 jours et demi et 20 jours après la naissance. D'un point de vue qualitatif, trois catégories cellulaires peuvent être distinguées: les oligodendrocytes, euxmêmes subdivisés en trois classes (grands, moyens, petits), les astrocytes et d'autres varieties cellulaires parmi lesquelles la microglie. D'un point de vue quantitatif, les oligodendrocytes, en particulier les petits, sont largement majoritaires. En effet, sur toute la période examinée les oligodendrocytes représentent près de 81% de la population totale. Sur le plan radio-autographique, l'index de marquage prédomine dans la classe des moyens oligodendrocytes. Ces résultats sont discutés, notamment par rapport aux processus de myélinisation dont les phénomènes de gliose constituent le préambule direct.
    Notes: Summary A study based on the histological identification and quantifying of the neuroglia cells, was carried out in the optic tract of the Rat on radioautographs after injection of tritiated thymidine. The assessment was made two and a half days and twenty days after birth. Qualitatively speaking, three cellular categories can be distinguished: the oligodendrocytes, themselves divided into three sorts (big, medium., small) the astrocytes and other cellular varieties including the microglia. Quantitatively speaking the oligodendrocytes, in particular the small ones, are decidedly more numerous. In fact, over the whole period under consideration the oligodendrocytes represent nearly 81% of the total population. From the point of view of the radio-autography the labeling index predominates in the medium oligodendrocyte group. These results are discussed with reference in particular to the myelination process which is preceded directly by the phenomena of gliosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234473
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  • 8
    Electronic Resource
    Electronic Resource
    Etude quantitative du marquage radioautographique dans le système nerveux du rat (1974)
    Springer
    Experimental brain research 21 (1974), S. 455-461 
    Details
    ISSN: 1432-1106
    Keywords: Quantitative radioautography ; Neural tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Une étude basée sur la quantification du marquage radioautographique a été conduite dans différentes régions du tube neural embryonnaire chez le Rat après injection de thymidine tritiée. Quand le délai entre l'injection et le sacrifice est court (moins de 5 heures), l'histogramme de distribution du nombre des grains recouvrant les cellules suit généralement la loi de Poisson. D'importantes modifications apparaissent, d'une part, quand ce délai augmente et, d'autre part, lorsque la quantification concerne les zones ventriculaires en régression fonctionnelle. La comparaison entre la méthode de comptage visuel des grains et la méthode semi-automatique montre que cette dernière introduit une légère dispersion des résultats. Ces observations permettent de définir les conditions primitives du marquage radioautographique et sont, par conséquent, les bases indispensables d'un modèle mathématique expliquant les caractéristiques du marquage dans les structures du cerveau chez l'animal adulte.
    Notes: Summary A study based on the quantification of radioautographic labelling was carried out in different regions of the neural tube of the rat embryo after injection of tritiated thymidine. When the period of time from injection to sacrifice is short (less than 5 hours), the histogram of the distribution of the number of grains on the cells generally follows Poisson's law. Noticeable variations appear on one hand, if the period between injection and sacrifice increases, and, on the other hand if the quantification concerns ventricular regions in functional regression. The comparison between the classical visual grain counting method and a semi-automatic one shows that the latter introduces a slight dispersion of the results. These observations enable us to specify the primary conditions of the radioautographic labelling, and are consequently the indispensable basis for a mathematical pattern, explaining the distribution of the labelling which is characteristic of the brain structures in the adult.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237164
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