bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the influence of optic stalk melanin on the chiasmatic pathways in the developing rodent visual system
Authors: Colello R. J. , Jeffery Glen 
Published: January 2005

AbstractIn a number of mammalian species, fibre outgrowth in the developing retinofugal pathway is coincident with the presence of melanin in the retinal part of the optic stalk. The presence of melanin is transient in this developing system and has been proposed to play a role in the guidance of retinofugal fibres. Further, it has been suggested that this stalk melanin accounts for the differences between the size of the uncrossed retinal component in pigmented and nonpigmented strains. However, a recent study showed that there is no melanin in the optic stalk of Manchester rats during fibre outgrowth. Since such rats supposedly have a normal pigment distribution and a normal pattern of decussation at the optic chiasm, this finding appears to undermine the suggested role played by stalk melanin in establishing the laterality of retinal fibre projections in other mammalian species.The aim of this study was to re‐evaluate the relationship between melanin in the stalk and the development of the retinofugal pathway in three strains of rat: the Wild type, Long Evans Hooded, and the Albino. The Albino rat, which lacks melanin‐bearing cells entirely, was shown to have the smallest uncrossed projection, approximately 1,340 ipsilaterally projecting cells (ipc), whereas the Long Evans (2,760 ipc) and the Wild‐type strain (2425 ipc) were found to have a larger uncrossed retinal component. In both pigmented strains, melanin was restricted to the eye cup and absent from the optic stalk throughout all stages of development. These results extend the finding that in the rat no correlation can be found between the size of the adult uncrossed retinofugal pathway and the existence of stalk melanin during development. Further, it was found that during initial outgrowth the distribution of fibres in the distal stalk was similar for all three strains, providing evidence that fibre topography does not account for the differences in the number of ipsilaterally projecting ganglion cell fibres.Finally, the position of earliest uncrossed fibres in the stalk was determined in the mouse, an animal with melanin‐bearing cells in this region. It was found that these fibres intermingled with crossed fibres throughout the length of the stalk and that their position within the stalk was similar in both pigmented and albino strains. These observations suggest that stalk pigment plays no specific role in the development of the chiasmatic pathway of retinofugal fibres in either the rat or the mouse.
Differential projections of the main and accessory olfactory bulb in the frog
Authors: Scalia Frank , Gallousis Gregory , Roca Suri 
Published: January 2005

AbstractThe central projections of the main olfactory bulb and the accessory olfactory bulb of the adult leopard frog (Rana pipiens) were reexamined, by using a horseradish peroxidase anterograde tracing method that fills axons with a continuous deposit of reaction product. The fine morphology preserved by this method allowed the terminal fields of the projection tracts to be delineated reliably, and for the first time. Herrick's amygdala has been newly subdivided into cortical and medial nuclei on the basis of cytoarchitecture, dendritic morphology, and the differential projections of the main and accessory olfactory tracts.The main olfactory bulb projects through the medial and lateral olfactory tracts to the postolfactory eminence, the rostral end of the medial cortex, the rostral end of the medial septal nucleus, the cortical amygdaloid nucleus, the nucleus of the hemispheric sulcus, and both the dorsal and ventral divisions of the lateral cortex, including its retrobulbar fringe. The lateral olfactory tract overlaps the dorsal edge of the striatal plate along the ventral border of the lateral cortex, but it is not certain whether any striatal cells are postsynaptic to the tract fibers. The lateral cortex is the largest of these territories, and receives the terminals of the main olfactory projection throughout its extent. It extends from the olfactory bulb to the posterior pole, and from the striatum to the summit of the hemisphere, where it borders the dorsal cortex. The medial and lateral olfactory tracts combine in the region of the amygdala to form a part of the stria medullaris thalami. These fibers cross in the habenular commissure and terminate in the contralateral cortical amygdaloid nucleus and periamygdaloid part of the lateral cortex. Cells projecting to the main olfactory bulb are found in the diagonal band and adjacent cell groups, but there is no evidence of an interbulbar projection arising from either the olfactory bulb proper or a putative anterior olfactory nucleus.The accessory olfactory bulb projects through the accessory olfactory tract to the medial and cortical amygdaloid nuclei. A fascicle of the tract crosses in the anterior commissure to terminate in the contralateral amygdala. While the main and accessory olfactory projections may converge in the cortical amygdaloid nucleus, the medial amygdaloid nucleus is connected exclusively with the accessory olfactory bulb.
Histamine: A putative afferent neurotransmitter in Limulus eyes
Authors: Battelle B.‐A. , Calman B. G. , Andrews A. W. , Grieco F. D. , Mleziva M. B. , Callaway J. C. , Stuart A. E. 
Published: January 2005

AbstractHistamine has been proposed as a photoreceptor neurotransmitter in two major groups of arthropods, the insects and the Crustacea. In this study biochemical and immunocytochemical approaches were used to examine the synthesis, endogenous content, and cellular distribution of histamine in the visual system of the horseshoe crab Limulus polyphemus, an ancient chelicerate arthropod. Studies with this animal have been critical to our understanding of the basic processes of vision. High‐voltage paper electrophoresis was used to assay for histamine synthesis in Limulus tissues incubated with radiolabeled histidine; histamine synthesis was detected in the lateral, median, and ventral eyes and optic nerves and in the visual centers in the brain. Endogenous histamine, assayed as its orthophthalaldehyde derivative by high‐performance liquid chromatography and electrochemical detection, was also detected in these tissues. Immunocytochemical analyses, with an antiserum directed against a protein conjugate of histamine, revealed histamine‐like immunoreactivity in the somata of photoreceptors in each of the eyes and in the regions of the brain where the photoreceptors terminate. Histamine‐like immunoreactivity was also intense in the cell bodies and axon collaterals of eccentric cells in the lateral eye and in eccentric cell projections in the brain. These results show that histamine is a major biogenic amine in the Limulus visual system, and they suggest that this amine is involved in transmitting visual information from the eyes to the brain and in lateral inhibition, a fundamental mechanism for processing visual information in the lateral eye.
Guinea pig pancreatic ganglia: Projections, transmitter content, and the type‐specific localization of monoamine oxidase
Authors: Kirchgessner A. L. , Pintar J. E. 
Published: January 2005

AbstractThe ganglionated plexus of the guinea pig pancreas was investigated by using histochemical, immunocytochemical, and tract‐tracing methods in order to determine whether pancreatic ganglia are analogous to the ganglia of the enteric nervous system (ENS). Three lines of evidence suggest that the ganglia of the pancreas appear to be interconnected with one another, as are enteric ganglia. First, microinjections of the retrograde tracer Fluoro‐Gold into individual pancreatic ganglia labeled the perikarya of neurons in distant pancreatic ganglia, whereas no labeling of neurons was observed if injections were placed in the connective tissue adjacent to pancreatic ganglia. Second, when the intercalating dye DiI was microinjected into single pancreatic ganglia in fixed tissues, DiI‐labeled terminals were found in additional pancreatic ganglia. Finally, microinjections of the β subunit of cholera toxin into individual pancreatic ganglia yielded similar results.The ganglionated plexus of the pancreas also expresses a diversity of transmitter content and cell type‐specific localization of monoamine oxidase (MAO) that is analogous to the ENS. In common with guinea pig enteric ganglia, pancreatic ganglia contain highly varicose 5‐hydroxytryptamine (5‐HT)‐immunoreactive axons and intrinsic neuropeptide Y (NPY)‐ and substance P (SP)‐immunoreactive neurons. The vast majority, but not all, of SP‐immunoreactive fibers in the pancreatic parenchyma also contain calcitonin gene‐related peptide (CGRP) immunoreactivity. MAO‐B was the primary type of MAO found in the intrinsic elements of the pancreas where it was located in neurons and fibers in the pancreatic parenchyma. In common with serotoninergic enteric neurons, MAO‐B immunoreactivity was not found at the LM level in pancreatic serotoninergic neurites. In contrast, NPY‐ and tyrosine hydroxylase (TH)‐immunoreactive perivascular axons were found to contain abundant MAO‐A, but no MAO‐B immunoreactivity. It is concluded that MAO‐B immunoreactivity is characteristic of a portion of the intrinsic innervation of the pancreas, whereas MAO‐A immunoreactivity is a marker for the extrinsic sympathetic innervation of the pancreas. Because of its receipt of a direct neural innervation from myenteric ganglia of the bowel (Kirchgessner and Gershon, '90: J. Neurosci 10:1626–1642), similar connections, transmitter content and localization of type‐specific MAO, the ganglionated plexus of the pancreas should be regarded as an extension or subset of the ENS.
Dendritic morphology of pyramidal neurones of the visual cortex of the rat: II. Parameter correlations
Authors: Larkman Alan U. 
Published: January 2005

AbstractThis study concerns the correlations between the various morphometric parameters obtained for the dendrites of neocortical pyramidal cells. The primary aims were to uncover underlying design principles in dendritic morphology, to see if these differed between different types of dendrite, and to see if estimates of parameters such as total dendritic shaft membrane area could be obtained from a limited number of measurements, avoiding the need to measure every dendritic segment. The data were from a sample of 39 pyramidal neurones, from layers 2/3 and 5 of the visual cortex of the rat, that had been injected with horseradish peroxidase, reconstructed, and measured with the light microscope as part of an earlier study (Larkman and Mason, '90: J. Neurosci. 10:1407–1414).Correlations between the somal area or the combined diameters of the stem segments and measures of the overall size of the dendrites were generally weak. For basal dendrites, the size of a tree was correlated with both its number of tips and the diameter of its stem segment, but these correlations were weaker for apical dendrites. Within individual cells, the diameter of any basal segment was closely related to the size of the tree arising from it, and quantitatively similar relations applied to apical oblique trees from the same cell. Terminal arbor trees showed relations that were similar in pattern but differed quantitatively, whereas apical trunk segment diameter correlations were often weak. In all cases, the number of tips in a tree was closely related to its size. Segment lengths, however, were not closely related to the size of the trees arising from them.It appears that at least some aspects of pyramidal dendritic morphology obey simple design rules. There was heterogeneity between trees of different types, although basal and oblique trees were very similar in most respects. It should prove possible to make use of correlations to estimate the sizes of basal, oblique, and terminal arbor trees from a limited number of measurements, but this does not seem to be possible for apical trunks.
Retinohypothalamic tract in the female albino rat: A study using horseradish peroxidase conjugated to cholera toxin
Authors: Levine Joel D. , Weiss Mark L. , Rosenwasser Alan M. , Miselis Richard R. 
Published: January 2005

AbstractThere are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT‐HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT‐HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri‐SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, alight projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.
Olfactory projections to the hypothalamus
Authors: Price J. L. , Slotnick B. M. , Revial M.‐F. 
Published: January 2005

AbstractElectrophysiological recording, together with anterograde and retrograde axonal tracers, was used to provide a comprehensive description of the origin and distribution of the olfactory input to the lateral hypothalamus. This input was much more substantial to the caudal part of the hypothalamus than to the rostral part and originates from several different areas of the olfactory cortex.Positive responses to electrical stimulation of the olfactory bulb were found consistently in the postero‐lateral hypothalamus, but only occasionally at more rostral levels. In agreement with this, injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in the posterior half of the lateral hypothalamus labeled cells in four cortical areas that receive input from the olfactory bulb: the anterior olfactory nucleus, the piriform cortex (in the deepest layer or ventral endopiriform nucleus), the olfactory tubercle (in the deep polymorphic layer), and the anterior cortical nucleus of the amygdala. Injections of WGA‐HRP in the anterolateral hypothalamus labeled cells only in the anterior cortical nucleus of the amygdala.Anterograde axonal tracing confirmed these projections. Injections of 3H‐leucine in the anterior olfactory nucleus, the piriform cortex, and the olfactory tubercle produced axonal label that was light and confined to the medial forebrain bundle in the rostral hypothalamus but was more substantial and extended throughout the lateral hypothalamic area caudally. Injections in the anterior cortical amygdaloid nucleus labeled axons in the anterior hypothalamus and in the premammillary nuclei as well as in the posterolateral hypothalamic area. In addition, a projection was demonstrated to the nuclei gemini from the polymorphic zone deep to the olfactory tubercle.Injections of two fluorescent retrograde tracers into the mediodorsal nucleus of the thalamus and the posterolateral hypothalamus showed that cells projecting to both diencephalic sites were intermingled in all of the olfactory cortical areas except the anterior olfactory nucleus, where cells were labeled only from the hypothalamus. In the deep layer of the piriform cortex and in the anterior cortical amygdaloid nucleus cells were also double labeled, indicating that they send collateral axons to both parts of the diencephalon.
Cortical connections of dorsal cortex rostral to V II in squirrel monkeys
Authors: Weller R. E. , Steele G. E. , Cusick C. G. 
Published: January 2005

AbstractA region of dorsal cortex along the rostral border of V II has been described as comprising a visual area or areas separate from more lateral cortex in both New and Old World primates. To evaluate these possibilities in squirrel monkeys, we studied patterns of cortical connections by injecting Fast Blue, Fluoro‐Gold, horseradish peroxidase, and wheat germ agglutinin conjugated to horseradish peroxidase into the dorsal region and related results to distinctions in myeloarchitecture. Our major conclusions are as follows. (1) The dorsal region (D) has distinctly different connections from the area found laterally, the caudal subdivision of the dorsolateral area (DLC). These include major connections with the rostral subdivision of the dorsolateral area (DLR), ventral posterior parietal cortex in the Sylvian fissure, the middle temporal area (MT), the medial superior temporal area (MST), ventral cortex just rostral to V II, and cortex in the inferior temporal sulcus. Weaker connections are with V I, V II, DLC, the fundal superior temporal area (FST), and the frontal lobe. In contrast, DLC, has strong connections with V II and inferior temporal (IT) cortex, weaker connections with DLR, and lacks connections with ventral posterior parietal cortex (Steele et al: J Comp Neurol 306:495–520, 1991). (2) Caudal and rostral aspects of dorsal cortex differ in the magnitude of connections with V I, V II, DLR, and FST. These differences are consistent with the previous proposal that at least two visual areas, caudal and rostral, occupy the dorsal region in squirrel monkeys (Krubitzer and Kaas: Visual Neurosci 5:165, 1990), but they could also reflect regional differences in the connections of a single visual area. (3) The dorsal region is more densely myelinated than surrounding cortex; however, rostral aspects of dorsal cortex are less myelinated than caudal aspects, again suggesting the existence of at least two areas. (4) The distinctiveness of connections between dorsal cortex and rostral as compared to caudal dorsolateral cortex provides further evidence for dividing the region of DL into two visual areas, DLC and DLR (Cusick and Kaas: Visual Neurosci 1:211, 1988; Steele et al: J Comp Neurol 306:495–520, 1991).
Alz‐50 immunoreactivity in the hypothalamus of the normal and Alzheimer human and the rat
Authors: Byne W. , Mattiace L. , Kress Y. , Davies P. 
Published: January 2005

AbstractAlz‐50 is a monoclonal antibody recognizing a 68 kilodalton protein that is abundant in Alzheimer's disease (AD) but not detectable by immunoblotting methods in normal brains. When used for immunohistochemistry in AD cortex, Alz‐50 recognizes large numbers of neurofibrillary tangles (NFT), neuritic plaques, and some neurons that show no evidence of neurofibrillary degeneration by conventional histopathological staining methods, Alz‐50 immunoreactivity is described at the light and electron microscopic levels in the hypothalamus of brains obtained at autopsy from normal and AD subjects. Alz‐50 immunoreactivity in the rat hypothalamus is also described. A well‐defined population of Alz‐50 immunoreactive hypothalamic neurons was identified in both the normal human and rat. At the light microscopic level in the normal human, immunoreactive neurons were most concentrated in the periventricular region, but were also scattered throughout the arcuate nucleus (ARC), lateral hypothalamic area, and tuberal region. Immunoreactive fibers were seen in the periventricular region, dorsal division of the ventromedial nucleus (VMNd), ARC, and external layer of the median eminence (ME). In the rat, reactive neurons were seen only in the periventricular region, and reactive fibers were seen in the periventricular zone, medial preoptic nuclear complex, suprachiasmatic nucleus, VMNd, ARC, and external layer of the ME. Ultrastructurally, all immunoreactivity in the normal human and rat hypothalamus was associated with intraneuronal vesicles. In the AD hypothalamus, Alz‐50 identified numerous senile plaques and NFT in addition to the cells and fibers that were stained in the normal brains. Immunoreactive plaques and NFT were most numerous in regions previously reported to undergo neurofibrillary degeneration. At the ultrastructural level, the immunoreactivity in the AD hypothalamus was associated with filaments as well as vesicles. The significance of the selective staining of a specific population of vesicles by Alz‐50 is unknown; however, the present results suggest that it is independent of AD pathology.
Differential innervation patterns of three divisions of frog auditory midbrain (torus semicircularis)
Authors: Feng Albert S. , Lin Wenyu 
Published: January 2005

AbstractThe connectivity pattern of the laminar, principal, and magnocellular nuclei of the frog torus semicircularis (TS) was investigated. A small amount of horseradish peroxidase was injected focally into individual divisions of the TS and anterograde and retrograde transport patterns were observed. Results of our tracing study showed that these divisions of the TS possessed distinct innervation patterns. The principal nucleus appeared to be the primary input port of the TS receiving extensive inputs from all caudal brainstem auditory nuclei bilaterally, but especially from the contralateral dorsal medullary nucleus and the ipsilateral superior olivary and lateral lemniscus nuclei. Descending projection to this nucleus was limited to that from the posterior thalamic nucleus. In contrast, the laminar nucleus, but even more markedly the magnocellular nucleus, received extensive descending inputs from numerous structures in the dorsal thalamus and less pronounced ascending afferents from caudal brainstem auditory nuclei. Similar to the afferent connection patterns, the efferent projections originating from these three toral divisions differed substantially. The principal nucleus gave restricted ascending projections, limited mainly to the caudal region of the posterior thalamic nucleus, a region important in processing spectral information of complex sounds, and the pretectal gray. Its descending projection was also somewhat restricted, being limited to the superior olivary and lateral lemniscus nuclei. The laminar nucleus and especially the magnocellular nucleus gave robust descending as well as ascending projections; these nuclei serve as the main output paths for the TS and provide the main routes by which auditory input reaches the central thalamic nucleus, a structure previously shown to be involved in temporal information processing.