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Pannese, Ennio; Gioia, Magda; Carandente, Orazio; Ventura, Raoul
doi: 10.1002/cne.902140302pmid: 6853754
With a quantitative method and serial sections a study was carried out under the electron microscope of the perikaryal projections of the neurons in the thoracic spinal ganglia of cat and rabbit. These projections usually appear as finger‐shaped evaginations which run roughly parallel to the surface of the nerve cell body. Their length ranges between 0.3 and 3.25 μm, and they show a nearly circular cross section with a rather uniform transverse diameter having an average value of about 0.2 μm.
Goshgarian, Harry G.; Koistinen, Jeanne M.; Schmidt, Eric R.
doi: 10.1002/cne.902140303pmid: 6853755
Most of the hypotheses that have been proposed to explain why the injured mammalian spinal cord is not capable of extensive regeneration have suggested that the internal milieu of the injured spinal cord is not conducive to repair. Relatively little attention has been directed toward neuronal cell death as being contributory to the minimal amount of spinal cord regeneration. The present study suggests that the availability of regenerating axons in the injured spinal cord may be limited by the death of axotomized supraspinal neurons in the adult mammal. Adult rats were subjected to a right spinal cord hemisection at T1 followed by a second, more rostral right hemisection at C2 Horseradish peroxidase (HRP) was injected into the rostral hemisection site to acquire information on the metabolic changes that occur in HRP‐labeled rubrospinal neurons after axotomy. In the experimental animals, a delay of 9‐219 days occurred between the two operations whereas there was no delay between the two procedures in the control animals. An analysis of neuronal counts indicated that although there was a statistically significant (P < 0.01) decrease in the number of labeled rubrospinal neurons in the contralateral red nucleus of the experimental animals compared to controls, there was also a smaller, yet significant (P < 0.01) increase in the number of nonlabeled neurons in the experimental animals. The mean total number (both labeled and nonla beled) of neurons in the experimental animals (2,269 ± 348 cells), however, was significantly lower (P < 0.01) than the mean total number of neurons in the control animals (3,473 ± 488 cells). Thus, it is concluded that extensive cell death occurs in the red nucleus of the adult rat following spinal cord hemisection.
Seil, Fredrick J.; Leiman, Arnold L.; Blank, Nathan K.
doi: 10.1002/cne.902140304pmid: 6853756
Granuloprival cerebellar cultures were transplanted after 9 or 16 days in vitro with cerebellar explants that had been exposed to kainic acid. The latter contained granule cells and differentiated glia, elements lacking in granuloprival cultures. Changes induced by transplantation observed by light microscopy included interposition of granule cells among the large cortical neurons of host explants; a reduction of the excess neurites of the Purkinje cell axon collateral system that is characteristic of granuloprival explants; and the appearance of myelinated fibers in previously unmyeli‐nated cultures. The most notable electrophysiologic consequence of transplantation was the disappearance of inhibition of cortical spontaneous activity in response to antidromic stimulation of Purkinje cell axons, correlating with the disappearance of excess neurites, and suggesting that Purkinje cell recurrent collateral inhibition was no longer the dominant mode of cortical inhibition. Restoration of missing elements in granuloprival cultures incited development of structural and functional characteristics resembling those of normal cerebellar explants.
Blank, Nathan K.; Seil, Fredrick J.
doi: 10.1002/cne.902140305pmid: 6853757
Cytosine arabinoside‐induced granuloprival cerebellar cultures lack both granule cells and differentiated glia and demonstrate marked synaptic reorganization. After kainic acid‐exposed cerebellar explants, which contain granule cells and mature glia, were transplanted to the granuloprival cultures, the following ultrastructural features were noted: (1) parallel fibers formed normal synapses with Purkinje cell dendritic spines as well as with basket/stellate cell somata; (2) sprouted Purkinje cell recurrent axon collateral terminals were markedly reduced in number; (3) Purkinje cells matured and lost perisomatic spines; (4) astroglia formed sheaths around Purkinje cell somata and dendrites; and (5) axonal myelination occurred. The transplanted cultures demonstrated ultrastructural restitution toward normal after addition of missing elements.
Porter, Linda L.; White, Edward L.
doi: 10.1002/cne.902140306pmid: 6853758
The afferent and efferent connections of the vibrissal representation within the mouse primary motor cortex (Msl) were identified by using the retrograde transport of horseradish peroxidase (HRP) and the anterograde transport of tritiated amino acids injected into Msl. Following aldehyde perfusion brains were frozen‐sectioned at 40 μm and reacted for HRP using the 3‐3′ diaminobenzidine‐cobalt chloride technique of Adams (77). Alternate HRP reacted sections were processed for autoradiography.
doi: 10.1002/cne.902140307pmid: 6853759
The development of the Purkinje cell in the cerebellar cortex of the opossum, Didelphis virginiana, was analyzed by using Golgi preparations and electron microscopy. The maturation process of the Purkinje cell was observed to occur in five stages: the immature stage, the perisomatic den‐drite stage, the perisomatic spine stage, the main dendrite stage, and the adult stage. These stages were first defined by Hendelman and Aggerwal (′80), using Golgi preparations of immature mouse cerebellum.
Chaouch, A.; Menetrey, D.; Binder, D.; Besson, J. M.
doi: 10.1002/cne.902140308pmid: 6853760
An anatomical technique based on the retrograde transport of horseradish perodidase (HRP) was used to investigate the progections of sponal cord neurions to the reticular formations in the rat. Both large and restricted injections were staggered all along the bulbar and pontine levels, involving the nucleus gigantocellularis, the nuclei reticularis pontis, pars oralis and cauladis and in some cases the nucleus raphé magnus.
Wilczynski, Walter; Northcutt, R. Glenn
doi: 10.1002/cne.902140309pmid: 6602152
Afferents to the dorsal and ventral striatum of the bullfrog (Rana catesbeiana) were revealed by horseradish peroxidase (HRP) histochemistry. Anterograde tracing techniques (autoradiography and anterograde HRP transport) were then used to confirm the projections and to describe their terminal fields within the striatum. The major input arises from the ipsi‐lateral lateral anterior and central thalamic nuclei, which receive tectal (Rubinson, ′68) and toral (Neary, ′74) input, respectively. These projections terminate in a dense, homogeneous field within the striatal neuropil adjacent to the cell plates of both striatal divisions. A second heavy input arises from the anterior entopeduncular nucleus bilaterally, with axons from the contralateral side crossing in the anterior commissure. This input terminates in both striatal divisions but is heaviest ventrally, Sparser inputs are present from the ipsilateral lateral and medial amygdalar nuclei, the preoptic area (mainly from the very caudal suprachiasmatic division), the posterior tuberculum, and the ipsilateral superficial isthmal reticular nucleus of the tegmentum. All these afferents, with the possible exception of the preoptic input, ascend to the striatum via the lateral forebrain bundle, and all innervate both striatal divisions. The preoptic input terminates within the cell plates, as well as subpially in a pattern similar to that described for tubercular input (Neary and Wilczynski, ′77). The tegmental input is very sparse and is most apparent superficially. Afferents from pallial telencephalic areas are not present, suggesting that although an‐urans receive striatal input from the diencephalon and mesencephalon, they do not possess a homolog of the mammalian corticostriatal system. Further, the extremely heavy input from the middle dorsal thalamic zone suggests that a major function of the anuran striatum involves processing sensory information from the midbrain roof.
Wilczynski, Walter; Northcutt, R. Glenn
doi: 10.1002/cne.902140310pmid: 6602153
Autoradiographic and degeneration techniques were used to describe striatal efferents in the bullfrog (Rana catesbeiana). Horseradish peroxidase (HRP) was then placed in the major terminal fields to reveal the striatal cells responsible for these projections. Except for the small ventral eminence of the lateral pallium immediately adjacent to the dorsal striatum, no pallial region receives a striatal projection. Most striatal efferents descend in the lateral forebrain bundle (LFB), passing through the anterior entopedun‐cular nucleus, where one large fascicle decussates in the anterior commissure and innervates the contralateral anterior entopeduncular nucleus and caudal ventral striatum. A smaller fascicle exits the LFB to terminate in the ipsilateral lateral amygdala. The remaining efferents continue caudal in the LFB through the posterior entopeduncular nucleus, with sparse projections to the ventral thalamus, the adjacent preoptic areas, and the posterior tuberculum leaving the bundle at various points. At pretectal levels, some efferents leave the LFB to run dorsally, through the caudal pole of the central thalamic nucleus and into the posterior division of the lateral nucleus and the lateral portion of the posterior thalamic nucleus. Efferents also continue caudal, through the superficial tegmental cell groups (nucleus profundus mesencephali and superficial isthmal reticular nucleus) before turning dorsomedially into the ventral anterodorsal, lateral anteroventral, and rostral pole of the posterodorsal tegmental fields. A small superficial projection continues to isthmal levels but cannot be traced beyond. Tegmental HRP injections retrogradely fill cells in the dorsal and ventral striatum as well as nucleus accumbens and the anterior entopeduncular nucleus. Pretectal HRP injections fill cells only in the caudal ventral striatum and anterior entopeduncular nucleus. Anterior entopeduncular nucleus HRP injections fill numerous cells in all striatal divisions, but some of this filling may be due to interrupted fibers of passage. Thus the anuran striatum, which receives its major input from thalamic nuclei relaying tectal and toral input, can in turn influence the midbrain roof via several disynaptic pathways: through the anterior entopeduncular nucleus, pretectum, and tegmentum, all of which project directly to the tectum and torus (Wilczynski and Northcutt, ′77; Wilczynski, ′81). Additional trisynaptic routes through the anterior entopeduncular nucleus and its pretectal and tegmental connections parallel the striatal routes.
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