| 1. |
- Agardh, E., et al.
(författare)
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Gamma‐aminobutyric acid‐ and glutamic acid decarboxylase‐immunoreactive neurons in the retina of different vertebrates
- 1987
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 258:4, s. 622-630
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Tidskriftsartikel (refereegranskat)abstract
- The localization of gamma‐aminobutyric acid (GABA)‐ and L‐glutamate 1 carboxy‐lyase (GAD)‐immunoreactive neurons was compared in the skate, frog, pigeon, chicken, rabbit, and man. Horizontal cells show both GABA and GAD immunoreactivity in the skate, frog, and bird. Certain amacrine cells show GABA and GAD immunoreactivity in all species. The distribution of GABA‐ and GAD‐immunoreactive cell bodies and cell processes was very similar, if not identical, in the skate and man. In the other species, cell populations with GAD immunoreactivity also showed GABA immunoreactivity. However, in the bird, frog, and rabbit, the GABA‐immunoreactive amacrine cells were at least twice as numerous as the GAD‐immunoreactive cells. In birds, the distributions of the GAD and GABA immunoreactivities were different in the sublayers of the inner plexiform layer. The reason for the difference is currently unknown. GABA‐immunoreactive bipolar‐like cells were seen in the frog.
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| 2. |
- Bras, H., et al.
(författare)
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Demonstration of initial axon collaterals of cells of origin of the ventral spinocerebellar tract in the cat
- 1988
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 273, s. 584-592
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Tidskriftsartikel (refereegranskat)abstract
- Neurones of origin of the ventral spinocerebellar tract were stained with intracellularly applied horseradish peroxidase to investigate whether they give off any initial axon collaterals. The neurones were located in the fourth and fifth lumbar segments and were identified by their antidromic activation following stimulation in the contralateral superior cerebellar peduncle. Nine of the 23 neurones with well‐stained axons were found to give off axon collaterals soon after the axons crossed the midline. The collaterals entered the contralateral ventral horn and branched within lamina VII and the dorsal part of lamina VIII. Collaterals were found arising only from neurones located in the middle of lamina VII and from axons which took a mediorostral direction. In all of these neurones excitatory postsynaptic potentials were evoked from group Ia afferents of at least some nerves, in addition to such potentials from Ib or unidentified group I afferents, and inhibitory postsynaptic potentials were evoked from group I and II afferents. The area of terminal branching of the collaterals suggests that they may supply contralateral ventral spinocerebellar neurones with information from muscles and/or mediate crossed reflexes from group I afferents. Copyright © 1988 Alan R. Liss, Inc.
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| 3. |
- Bras, H., et al.
(författare)
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Morphology of midlumbar interneurones relaying information from group II muscle afferents in the cat spinal cord
- 1989
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 290, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- The morphology of midlumbar interneurones with peripheral input from group II muscle afferents was analysed after intracellular injection of horseradish peroxidase (HRP). Twenty‐three interneurones were stained intrasomatically and five others intra‐axonally. The majority (10 of 13) of interneurones located in lamina VII (intermediate zone and ventral horn interneurones) were found to project ipsilaterally. They had medium‐sized somata and dendrites projecting radially over a distance of more than 1 mm. All of these neurones had axons that projected caudally within the ventral part of the lateral funiculus or in the lateral part of the ventral funiculus, although four had in addition an ascending secondary axonal branch. Numerous axon collaterals were given off from these axons, both before and after they left the grey matter. The collaterals arborized within laminae VII, VIII, and IX, where they covered the area of several motor nuclei. Intra‐axonal labelling of five neurones with similar input and axon trajectories revealed several axon collaterals given off between the cell body and the terminal projection areas in L7 or S1 segments. Only three of the labelled interneurones located in lamina VII and displaying the same kind of input had axons with different destinations; their axons crossed to the opposite side of the spinal cord and ascended within the contralateral ventral funiculus. These were large neurones with extensive dendritic trees, which had fairly thick axons with initial axon collaterals that branched primarily ipsilaterally (within laminae V‐VIII). Interneurones located in lamina V and in the bordering parts of laminae IV and VI (dorsal horn interneurones; n = 10) constituted a very nonhomogenous population. They projected either ipsilaterally or contralaterally and had either ascending or descending axons running in either the lateral or ventral funiculi. Generally, dorsal horn interneurones had cell bodies smaller than those of intermediate zone and ventral horn interneurones, and their dendrites extended less extensively and less uniformly around the soma. Their initial axon collaterals branched primarily in the dorsal horn, or in lamina VII, but not in or close to the motor nuclei. Our results support the conclusions of previous physiological studies that the intermediate zone and ventral horn midlumbar interneurones with group II input and that project to motor nuclei have collateral actions on other interneurones in the L4‐L6 segments, and that dorsal horn interneurones do not project to motoneurones, but have as their targets other interneurones or ascending cells. On the other hand, we have not found any projections of L4 interneurones with input from either group I or group I1 muscle afferents, to Clarke's column, in contrast to the projections of interneurones in reflex pathways from tendon organs from more caudal segments. Copyright © 1989 Alan R. Liss, Inc.
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| 4. |
- Ekström, Peter, et al.
(författare)
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Antibodies against retinal photoreceptor‐specific proteins reveal axonal projections from the photosensory pineal organ in teleosts
- 1987
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 265:1, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- With the aid of specific antisera to the retinal proteins S‐antigen and α‐transducin and to the rhodopsin apoprotein opsin, we have labeled various cell populations in the pineal organ, parapineal organ, habenular nucleus, and subcommissural organ in two teleost species: the rainbow trout and the European minnow. Although these proteins are associated with photoreceptor functions, not only photoreceptor cells but also the majority of parenchymal cells in the pineal organ were immunoreactive. Immunoreactive cells with dendrite‐ and axonlike processes were observed also in the parapineal organ and the habenular nucleus. Furthermore, S‐antigen‐immunoreactive, long, axonal processes were observed in the pineal organ and could be traced from the pineal organ to the habenular nucleus and to the pretectal area. In the light of recent HRP electron microscopical and immunocytochemical studies we propose (1) that not only the classical pineal photoreceptor cells of poikilothermic vertebrates but also other types of CSF‐contacting neurons may be the phylogenetic ancestors of mammalian pinealocytes, and (2) a close interrelationship between the pineal organ and the limbic system, effectuated by the direct projections from pineal photoreceptors/CSF‐contacting neurons/pinealocytes to the habenular nucleus, and by displaced “pinealocytelike” elements scattered in the habenular nucleus.
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| 5. |
- Ekström, Peter
(författare)
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Distribution of choline acetyltransferase‐immunoreactive neurons in the brain of a cyprinid teleost (Phoxinus phoxinus L.)
- 1987
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 256:4, s. 494-515
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of putative cholinergic neurons in the brain of a cyprinid teleost was investigated by immunocytochemistry, with well‐characterized polyclonal antibodies to porcine choline acetyltransferase (ChAT), correlated with acetylcholinesterase (AChE) histochemistry. AChE‐positive neurons were more numerous than GhAT‐immunoreactive (ChAT‐IR) neurons. Regions with ChAT‐IR neurons generally also contained AChE‐positive ones, but regions with AChE‐positive neurons often did not contain (or contained only small numbers of) ChAT‐IR neurons. ChAT‐IR neurons were located in the brainstem cranial nerve motor nuclei, in the brainstem reticular formation, in the nucleus laterals valvulae and an adjacent subnucleus “a,” in the nucleus isthmi, and in the stratum griseum periventriculare of the tectum opticum. All neurons in these areas were AChE positive. ChAT‐IR neurons were also observed within the boundaries of the nucleus sensibilis nervi trigemini and the n. descendens nervi trigemini. The periventricular hypothalamus and the paraventricular organ, the pineal organ, and (possibly) the nucleus suprachiasmaticus also contained ChAT‐IR neurons. In these areas, AChE activity was either low or located mainly in neurons other than the ChAT‐IR ones. A small population of ChAT‐IR neurons was observed in area ventralis telencephali pars lateralis. This was the only telencephalic ChAT‐IR cell group. Furthermore, some previously unrecognized cell groups were observed. A small number of ChAT‐IR neurons, located on the dorsal aspect of the fasciculus longitudinalis medialis (caudal to n. raphe dorsalis), emitted axons that passed caudally along the raphe midline and innervated some of the large reticular neurons. Another group of ChAT‐IR neurons was observed caudal to the thalamic nucleus centralis posterior and was tentatively designed n. tractus rotundus, on the basis of the neuronal morphology. The almost Golgilike staining of some of the ChAT‐IR cell groups permitted the identification of their efferent connections and the areas covered by their dendrites.
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| 6. |
- Ekström, Peter, et al.
(författare)
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Distribution of noradrenaline in the brain of the teleost Gasterosteus aculeatus L. : An immunohistochemical analysis
- 1986
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 254:3, s. 297-313
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of noradrenergic neurons in the brain of the threespined stickleback was demonstrated with the indirect peroxidase‐antiperoxidase (PAP) immunohistochemical method with antibodies against a noradrenaline‐bovine serum albumin conjugate. Noradrenergic neuronal somata were exclusively located in the isthmal area of the brain stem and in the lower medulla. Noradrenergic varicose axons innervate the reticular formation, motor nuclei, and interpeduncular nucleus of the brain stem, the hypothalamus and habenular nuclei, various parts of the area dorsalis telencephali (forebrain pallium), and the olfactory bulbs. Scattered noradrenergic axons were observed in the optic tectum and in various parts of the cerebellum. It is concluded that the isthmal cell group of the stickleback is, on topological and cytoarchitectonic grounds, equivalent to the ventral portion of the locus coeruleus/subcoeruleus area of amniotes, but that its efferent connections display features characteristic both of those originating in the locus coeruleus, and in the lateral tegmental cell groups of mammals.
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| 7. |
- Nilsson, O G, et al.
(författare)
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Comparison of growth and reinnervation properties of cholinergic neurons from different brain regions grafted to the hippocampus
- 1988
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 268:2, s. 22-204
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Tidskriftsartikel (refereegranskat)abstract
- Grafts of five different types of central cholinergic neurons, from the septal-diagonal band region, the nucleus basalis magnocellularis region (NBM), the striatum, the pontomesencephalic tegmentum of the brainstem, and the spinal cord, were compared with respect to their ability to grow and to reinnervate the cholinergically denervated hippocampal formation of adult rats. The areas were dissected from 14 to 15-day-old rat fetuses, and the same number of viable cells (35 X 10(4) from each of the different regions were stereotaxically injected as cell suspensions into the hippocampus of rats subjected to a transection of the intrinsic septo-hippocampal cholinergic pathways. At 17-19 weeks after transplantation, the various graft types differed considerably in their volume, the total amount of acetylcholinesterase (AChE)-positive fiber outgrowth, and the innervation pattern and morphology of the AChE-positive fibers growing into the host hippocampus. On average the NBM and spinal cord grafts had grown to become three to four times larger than the septal and the brainstem grafts, and 15-20 times larger than the striatal grafts. By contrast, the total ingrowth score of AChE-positive fibers in the host hippocampus from the septal grafts was about twice that of the NBM and brainstem grafts, about five times greater than the striatal grafts, and about six times greater than that of the spinal cord grafts. The large NBM grafts thus exhibited similar fiber outgrowth to the much smaller brainstem grafts, and the AChE-positive neurons of the grafted spinal cord grew very poorly into the hippocampus despite the fact that they survived very well. The innervation pattern and morphological features of the ingrowing AChE-positive fibers in the host hippocampus proper and in the dentate gyrus resembled those of normal rats in animals with grafts from any of the three forebrain regions (i.e., septum, NBM, or striatum), whereas ingrowth from the brainstem and spinal cord grafts were markedly abnormal with respect to both innervation pattern and fiber morphology. These results provide further evidence that the overall survival, growth, and fiber outgrowth of intracerebral neural grafts depend on interactions with the surrounding host tissue. Since the ability to reinnervate the previously denervated host target was greatest for the neuron type normally innervating that area, i.e., the septal-diagonal band neurons, we conclude that neuronal properties beyond the transmitter type are essential for the optimal performance of implanted neurons in intracerebral grafting experiments.
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