| 51. |
- Ekström, Peter, et al.
(författare)
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Distribution of 5‐hydroxytryptamine (serotonin) in the brain of the teleost Gasterosteus aculeatus L.
- 1984
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 226:3, s. 307-320
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of serotoninergic neurons in the brain of the three‐spined stickleback was demonstrated with the indirect peroxidase‐antiperoxidase (PAP) immunohistochemical method with antibodies against serotonin. Serotoninergic perikarya were demonstrated in the brainstem reticular formation (nucleus raphe dorsalis, nucleus raphe medialis, and nucleus tegmenti dorsalis lateralis) and in the periventricular ventral thalamus and hypothalamus (nucleus ventromedialis thalami, nucleus posterioris periventricularis, nucleus recessus lateralis, and nucleus recessus posterioris). After pharmacological pretreatment of the animals with a monoamine oxidase inhibitor, serotoninergic perikarya were also visualized in area praetectalis and in the medial brainstem, caudal to nucleus raphe medialis. Whereas the cell groups of the brainstem give rise to both ascending and descending pathways, it was not possible to analyze the distribution of efferent projections from the diencephalic cell groups. Distribution of serotoninergic axons showed marked regional differences. Only scattered varicose fibers were demonstrated in the cerebellum, the facial lobes, and the lateral line lobes. In the mesencephalon, the dorsal periventricular tegmentum and the central gray receive only small numbers of serotoninergic axons, while torus semicircularis and the visual layers of tectum opticum are profusely innervated. In the diencephalon, the hypothalamus and ventral thalamus generally display the highest density of serotoninergic axons. Exceptions are found in nucleus glomerulosus and the ventromedial portion of lobus inferioris, where densities are low. In the telencephalon, the density of serotoninergic axons is very high in area dorsalis pars medialis and pars lateralis dorsalis, but low in area dorsalis pars dorsalis and pars lateralis ventralis, and intermediate in area ventralis.
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| 52. |
- 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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| 53. |
- 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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| 54. |
- Ekström, Peter, et al.
(författare)
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Electron microscopic analysis of S‐antigen‐ and serotonin‐immuoreactive neural and sensory elements in the photosensory pineal organ of the salmon
- 1990
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 292:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- Photoreceptor cells in the pineal complex of poikilothermic vertebrates are regarded as homologous with the neuroendocrine pinealocytes in the mammalian pineal organ. They possess an indolamine metabolism, and they contain a number of substances that are immunochemically similar to phototransduction‐related proteins otherwise found in photoreceptors of the lateral eye retina. Using correlative light and electron microscopic pre‐embedding immunocytochemistry, we have identified photosensory and neural elements that are immunoreactive with specific antisera against serotonin (5‐hydroxytryptamine) and the 48 kDa soluble protein S‐antigen (arrestin). One type of serotonin‐immunoreactive (5HTir) photoreceptor cell was identified. This was characterized by a short basal pole, into which an immunoreactive (postsynaptic?) element protruded. Two types of ‐antigen‐immunoreactive (SAir) photoreceptor cells were observed, one characterized by a short basal pole, similar to that of the 5HTir photoreceptors and the other characterized by a long, extensively branching basal pole. In addition, two types of neurons bearing no morphological specializations typical of photoreceptor cells were SAir: bipolar neurons and multipolar neurons. These were often situated dorsally in the pineal organ. The results indicate an emergence of multiple lines of photoreceptor‐derived “pinealocytes” either early in phylogeny, or independently in different taxa. The results are discussed in relation to current theories of pineal evolution.
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| 55. |
- el Jundi, Basil, et al.
(författare)
-
Neuroarchitecture of the dung beetle central complex
- 2018
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 526:16, s. 2612-2630
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Tidskriftsartikel (refereegranskat)abstract
- Despite their tiny brains, insects show impressive abilities when navigating over short distances during path integration or during migration over thousands of kilometers across entire continents. Celestial compass cues often play an important role as references during navigation. In contrast to many other insects, South African dung beetles rely exclusively on celestial cues for visual reference during orientation. After finding a dung pile, these animals cut off a piece of dung from the pat, shape it into a ball and roll it away along a straight path until a suitable place for underground consumption is found. To maintain a constant bearing, a brain region in the beetle's brain, called the central complex, is crucially involved in the processing of skylight cues, similar to what has already been shown for path-integrating and migrating insects. In this study, we characterized the neuroanatomy of the sky-compass network and the central complex in the dung beetle brain in detail. Using tracer injections, combined with imaging and 3D modeling, we describe the anatomy of the possible sky-compass network in the central brain. We used a quantitative approach to study the central-complex network and found that several types of neuron exhibit a highly organized connectivity pattern. The architecture of the sky-compass network and central complex is similar to that described in insects that perform path integration or are migratory. This suggests that, despite their different orientation behaviors, this neural circuitry for compass orientation is highly conserved among the insects.
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| 56. |
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| 57. |
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| 58. |
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| 59. |
- Elofsson, Ulf O. E., et al.
(författare)
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Relationships between sex and the size and number of forebrain gonadotropin-releasing hormone-immunoreactive neurones in the ballan wrasse (Labrus berggylta), a protogynous hermaphrodite.
- 1999
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Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 410:1, s. 158-70
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Tidskriftsartikel (refereegranskat)abstract
- This study is the first to examine the brain gonadotropin-releasing hormone (GnRH) cell population phenotype in a protogynous and monandric sequentially hermaphroditic fish. Male ballan wrasse (Labrus berggylta) had on average higher numbers of GnRH-immunoreactive (GnRH-ir) cells within the brain preoptic area (POA) than females, a difference not found in GnRH-ir cells in other brain regions. Furthermore, in males, but not females, the number of these POA GnRH-ir cells correlated with body size. Maturational state (prespawning or postspawning) had marked effects on mean profile sizes (but not numbers) of both GnRH-ir cell bodies and cell nuclei, even when existing differences in body size and allometric relationships had been taken into account. Postspawning males tended to have larger GnRH-ir profiles in all brain regions relative to both prespawning males and females. Moreover, the GnRH-ir cell number in POA, and the cell body profile size in both POA and at the level of the anterior commissure, correlated with gonad size in spermiated prespawning males, indicating a relationship between both size and number of GnRH cells and male gonadal development. These results suggest that temporary changes in the size of brain GnRH-ir neurones are coupled to the male spawning cycle, and that permanent POA GnRH-ir cell number changes are involved in the process of sex change in sequential hermaphrodites. However, smaller males had no more preoptic GnRH-ir cells than equally sized females, which may argue against a proximate inducing role of GnRH cell number changes in naturally occurring sex reversal.
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| 60. |
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