Dense core vesicles during photoreceptor development

Summary The presence of dense core vesicles in the terminal expansions of photoreceptors in development is decribed in the chick embryo retina, from the 16th to the 18th day of incubation.Acknowledgment. J.M.G.-G. was supported by a grant from the Comision Asesora de Investigacion Cientifica y Tecnica, Madrid, Spain.     

Brain stem projections to the cerebral cortex in the rat.

By means of the HRP method it was shown that the entire cerebral cortex, but in greater proportion the frontal and posterior temporo-parietal regions, receive fibres from the dorsal and medial raphe nuclei and from the locus coeruleus. In contrast, the pars compacta substantiae nigrae and the tegmental area send projections to the motor and cingular areas respectively.     

Cajal cells of the rabbit cerebral cortex

Resumen Las células deCajal en los animales estudiados, no poseen axon. Morfológicamente son similares a las grandes amacrinas de la plexiforme interna de la retina.

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Supported by a grant from The Seguridad Social, Instituto Nacional de Previsión.     

The cerebral cortex regulates immune responses in the mouse

Ablation of the left cerebral cortex abrogates the production of thymic hormone, reduces the number of spleen T cells and impairs immunization with sheep erythrocytes. In addition, partial decortication inhibits the ability of sodium diethyldithiocarbamate (DTC) to increase the level of circulating thymic hormone, as well as the number of splenic T cells. Therefore, the cerebral cortex would display an important role to maintain body integrity and relations with the external environment, through its effects on the immune system.     

Getting there and being there in the cerebral cortex

The mammalian neocortex is composed of functional areas that are specified to process particular aspects of information. How is this specification achieved during development? Since cells migrate to their final positions in the developing nervous system, a central issue is the relation between cellular migration and positional information. This review combines evidence for early positional specification in the developing cortex with evidence for cellular dispersion during migration. A model is suggested whereby stable cues provide positional information and minorities of ‘displaced’ cells are respecified accordingly. Comparison with other parts of the CNS reveals that cellular dispersal is ubiquitous and has to be included in any mechanism relaying positional specification. Ontogenetic and phylogenetic considerations suggest that radial glial cells might provide the positional information in the developing nervous system.     

The specification of neuronal identity in the mammalian cerebral cortex

Summary The determination of neuronal fate in the developing cerebral cortex has been studied by tracking normal cell lineages in the cortex, and by testing the commitment of young cortical neurons to their normal fates. These studies together suggest that neuronal progenitors are multipotent during development and have the potential to produce neurons destined for many or all of the cortical layers. However, the laminar identity of an individual neuron appears to be specified through environmental interactions at the time of the cell's temrinal mitotic division, prior to its migration into the cortical plate.     

Depression of neurones in the rat cerebral cortex by leptazol

Summary The convulsant drug leptazol was applied by microiontophoresis to 116 neurones in the cerebral cortex of rats. The firing of 101 cells was reduced. Only 6 cells were excited.     

The specification of neuronal identity in the mammalian cerebral cortex

The determination of neuronal fate in the developing cerebral cortex has been studied by tracking normal cell lineages in the cortex, and by testing the commitment of young cortical neurons to their normal fates. These studies together suggest that neuronal progenitors are multipotent during development and have the potential to produce neurons destined for many or all of the cortical layers. However, the laminar identity of an individual neuron appears to be specified through environmental interactions at the time of the cell's terminal mitotic division, prior to its migration into the cortical plate.     

Brain stem projections to the cerebral cortex in the rat

Summary By means of the HRP method it was shown that the entire cerebral cortex, but in greater proportion the frontal and posterior temporo-parietal regions, receive fibres from the dorsal and medial raphe nuclei and from the locus coeruleus. In contrast, the pars compacta substantiae nigrae and the tegmental area send projections to the motor and cingular areas respectively.     

Alteration in catecholamines in local cerebral cortex lesions

Zusammenfassung Nachweis, dass corticale Läsionen eine Akkumulation von Noradrenalin an der Läsionsstelle hervorrufen.

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I wish to express my thanks to Dr.Catherine Mytilineou, Dr.Lucien Côté and Mrs.Irene Tar for their assistance in this study.     

Monoamine pathways to the cerebellum and cerebral cortex

Zusammenfassung In kombinierter histochemischer und biochemischer Untersuchung werden Dopamin-, Noradrenalin-und 5-Hydroxytryptamin-Neurone nach Entfernung von Cortex cerebri und Cerebellum studiert. Es ergibt sich, dass die Noradrenalin-Nerventerminale, welche Cortex cerebri und Cerebellum innervieren, vermutlich von feinen Axonen her stammen, deren Zellkörper mindestens zum Teil in der Formatio reticularis der Medulla oblongata gelegen sind. Die Noradrenalin-und 5-Hydroxytryptamin-Axone, die nach dem Cortex cerebri ziehen, passieren vermutlich zur Hauptsache das Cingulum.     

Cell lineage and cell migration in the developing cerebral cortex

Summary Modern techniques which trace lineages of individual progenitor cells have provided some clues about the processes that determine cell fate in the brain, and have also given us some information about migratory patterns of clonally related cells. In many parts of the central nervous system, progenitors are multipotent; single clones can contain multiple neuronal types or even mixtures of neurons and glia. In addition, one can observe a wide distribution in clone size, even when marking is done in a narrow time window. This suggests that progenitor cells may be fairly plastic and responsive to environmental signals. In the developing cortex, clonally related cells are initially grouped near each other, as in the retina and tectum. However, the subsequent migration of these cells from the ventricular zone to the cortex along glial fibers is accompanied by a progressive dispersion of clonally related neurons.