bluuebunny/crossref_metadata_2025_split huggingface dataset:
Afferent and efferent connections of cerebellar lobe C3 of the mormyrid fish Gnathonemus petersi: An HRP study
Authors: Meek J. , Nieuwenhuys R. , Elsevier D. 
Published: January 2005

AbstractThe present paper is devoted to the extrinsic connections of lobe C3 of the highly differentiated corpus cerebelli of the electric fish Gnathonemus petersi. For this purpose, HRP injections or gels were placed in distinct parts of lobe C3 or its peduncle, in the pretectal region, and in the eye. Moreover, the presence of serotonin and tyrosine‐hydroxylase was studied with immunohistochemical methods.The afferent connections of the rostral and caudal part of lobe C3 appear to differ considerably. Although both parts receive comparable projections from two pretectal nuclei (termed nucleus geniculatus and dorsal anterior pretectal nucleus) and the inferior olive, they receive projections from different parts of the nucleus lateralis valvulae, a large cell mass in the midbrain tegmentum, composed of small, tightly packed neurons. The caudal part of lobe C3 receives a projection from the most rostromedial cap of cells of this nucleus, whereas the rostral cap of lobe C3 receives efferents from the neighboring, more caudolateral, zone of cells of the nucleus lateralis valvulae. The caudal part of lobe C3, but not its rostral part, receives an additional projection from a nucleus in the isthmus region, termed nucleus Q. This nucleus sends a collateral projection to the torus longitudinalis.The efferents of both parts of lobe C3 project to slightly different parts of the midbrain tegmentum and the nucleus reticularis superior, and originate at least partly from eurydendroid cells. None of the nuclei and fiber tracts labeled could be shown to contain serotonin or catecholamines.The connections of lobe C3, as revealed by the present study, are compared with those of other parts of the mormyrid cerebellum and with those of the corpus cerebelli of other teleosts, with emphasis on the homology and functional significance of pretectocerebellar connections, the topical order in the cerebellar projections of the nucleus lateralis valvulae, and the relations between the cerebellum and torus longitudinalis. Comparison of the cerebellar connections in different teleostean species suggests that the strong development and the considerable differentiation of the cerebellum of mormyrids are related to at least two types of changes in the extrinsic connections, i.e.: (1) a redistribution or parcelling of connections and (2) the development of connections specific for mormyrids.
Organisation of lateral line and auditory areas in the midbrain of Xenopus laevis
Authors: Lowe D. A. 
Published: January 2005

AbstractLateral line areas in the midbrain of Xenopus laevis were identified by recording evoked potentials and neural activity elicited by stimulating anterior and posterior lateral line nerves. Spike activity was found in the lateral half of the optic tectum, ventrolateral tectum, and torus semicircularis. Contra‐ and ipsilateral lateral line pathways to these regions were identified. Spike discharge was associated with an evoked potential (EP) consisting of a large negative‐positive wave sometimes preceded by a small positive‐negative deflection. EP depth profiles varied according to electrode position within the lateral line midbrain projection field. In the middle of the field a dramatic increase in EP growth occurred as the electrode passed through the torus semicircularis, with peak amplitudes being achieved 900–1,100 μm from the surface within nucleus principalis and monocellularis. Tracks at the lateral edge of the field showed a steady growth of EP, with peak amplitudes around 600 μm as the electrode passed through ventrolateral tectum. Auditory responses to tone pips were found in the nucleus laminaris and principalis in caudomedial regions of the torus semicircularis, in areas lying medial to the main centers of lateral line evoked activity; this is a similar organisation to that found in teleost fish. The results indicate the torus semicircularis and deep layers of the lateral tectum to be involved in lateral line processing Some topographic separation of the representation of anterior and posterior lateral line systems is indicated. The possible involvement of these areas in lateral line stimulus localisation is discussed.
Ultrastructure of spinal efferents to the lateral reticular nucleus: An EM study using anterograde transport of WGA‐HRP complex
Authors: Westman J. , Danckwardt‐Lillieström N. , Dietrichs E. , Svensson B. A. , Walberg F. 
Published: January 2005

AbstractAnterograde transport of lectin‐conjugated horseradish peroxidase and subsequent incubation with tetramethylbenzidine were employed to label the spinal terminals within the feline lateral reticular nucleus (NRL) for ultrastructural identification. Quantitative studies demonstrated that compared to the unlabelled terminals the spinal boutons were more than twice as large and contained fewer synaptic vesicles. Most of the synaptic contacts of the labelled terminals were located on dendritic shafts but contacts on dendritic spines as well as perikarya were also present. In four cases (all with cervical injections), the postsynaptic cells could be studied in the transversal sections of the medulla in the nuclear plane. The neurons were large and elongated with longest and shortest diameters of about 60 × 30 μm, belonging to the largest category of cells within the NRL. The observations were discussed and related to the findings made in other studies of the NRL.
Fine structure of the optic fiber termination layer in the tectum of the teleost Rutilus: A stereological and morphometric study
Authors: Peyrichoux J. , Pierre J. , Repérant J. , Rio J. P. 
Published: January 2005

AbstractThe stratum fibrosum et griseum superficial. (SFGS) of the Rutilus optic tectum, which receives a massive fiber from the projection from the contralateral retina, was studied by electron microscopy The qualitative and quantitative analysis of the laterodorsal (LD) portion of the stratum involved both a stereological examination of the different elements and a morphometric study of the various profiles containing synaptic vesicles (PCSVs). The relative volume of each element in the LD SFGS was as follows: myelinated and unmyelinated axons, 6.6%; PCSVs, 38%; dendrites without vesicles, spines, and cell bodies, 41.7%; glia, 10.5%. With the fixation employed, 35% of PCSVs showed spheroidal synaptic vesicles. These profiles could be subdivided into three types: (1) S1 (23.5%) represented optic terminals, since they degenerated after retinal ablation or were labeled after intraocular injection of HEP or [3H] proline. Three subgroups of S1 were identified: Slm‐profiles containing clear mitochondria;Sli‐isolated profiles that were contiguous with S1m and lacked mitochondria;Sli‐isolated profiles without mitochondria. (2)S2(9.3%) were characterised mainly by their dark mitochondria.(3)S3 (2.2%) corresponded to small nonvisual terminals that were isolated and lacked mitochondria. The PCSVs with pleiomorphic synaptic vesicles (65%) were subdivided into three groups: P1 (38%), P2 (19%), and P3 (8%). P1 and P2 were axonal in nature; P2 could be distinguished from P1 by a greater density of synaptic vesicles. P3 was of dendritic origin. Analysis of synaptic patterns revealed a small number of serial synapses. The presynaptic elements were optic boutons, whereas the intermediate profiles were dendrites with synaptic vesicles (P3). Results are compared with ultrastructural data obtained in the superficial tectal layers of other teleosts and other vertebrate groups.
Central projections of the ethmoidal nerve of the cat as determined by the horseradish peroxidase tracer technique
Authors: Lucier Gregory E. , Egizii Rita 
Published: January 2005

AbstractThe ethmoidal nerve innervates the nasal mucosa and constitutes the afferent limb of several upper airway protective reflexes. Protective reflexes, such as sneezing, coughing, and apnea, are those reflexes that either expel foreign substances from the respiratory tract or stop them from gaining access to the lungs. The afferents for nasal receptors are thought to be a part of the trigeminal system rather than olfactory in nature. The objective of this study was to localize the cell bodies of these ethmoidal afferents and to trace the central projections of these neurons. Horseradish peroxidase was applied to the ethmoidal nerve in 11 adult cats. Following a survival period of 48‐72 hours, the animals were killed and the tissue was processed according to the tetramethylbenzidine method. Reaction product was localized in cell bodies within the trigeminal ganglion, concentrated caudal to the entrance of the ophthalmic trunk of the trigeminal nerve. Transganglionic projections to the spinal trigeminal nucleus were localized primarily in the subnucleus interpolaris and in layers I and II of the subnucleus caudalis. There was also reaction product in cell bodies within the mesencephalic trigeminal nucleus. These results are in keeping with projections of other ophthalmic division receptor afferents, such as the cornea and the supraorbital nerve.
Neurotensin in the rat parabrachial region: Ultrastructural localization and extrinsic sources of immunoreactivity
Authors: Milner T. A. , Pickel Virginia M. 
Published: January 2005

AbstractWe sought to determine (1) the ultrastructural localization and (2) the extrinsic sources of neurotensin‐like immunoreactivity (NTLI) in the parabrachial region (PBR). The brains from untreated adult male rats and from others that received intraventricular injections of colchicine (100 μg/7.5 μl saline) 24 hours prior to death were fixed by perfusion with acrolein or glutaraldehyde and paraformaldehyde. Coronal sections were immunocytochemically labeled with a polyclonal rabbit antiserum to neurotensin and the PAP method. Western dot‐blots and immunocytochemical labeling with adsorbed antiserum revealed significant cross‐reaction only against NT, NT8‐13, and glutamine (Gln)4‐NT.In the ultrastructural study, the most numerous labeled profiles were axons and axon terminals in both colchicine‐treated and control animals. The terminals containing NTLI were characterized by a mixed population of small, clear and large, dense core vesicles; asymmetric junctions principally with unlabeled dendrites; and a few synaptic specializations with unlabeled axon terminals. Compared to axon terminals, relatively few perikarya or dendrites had detectable levels of NTLI in either untreated or colchicine‐treated animals. The labeled perikarya measured 8‐10 μm in longest cross‐sectional diameter, contained NTLI throughout a narrow rim of cytoplasm, and received a few somatic synapses from unlabeled terminals. From the relative density of axon terminals and sparsity of perikarya and dendrites, we conclude that the NTLI in the PBR is principally derived from extrinsic neurons. However, the intrinsic neurons with NTLI may also contribute to the immunoreactivity in the axon terminals of the PBR.We sought to determine the precise location of the extrinsic neurons that contribute to the NTLI in axon terminals in the PBR. Following unilateral injections of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP), dual labeling was most evident in a large population of neurons located in the dorsal, medial and commissural nuclei of the solitary tracts, ipsilateral to the side of the injection. However, a few perikarya containing both the retrogradely transported WGA‐HRP and immunocytochemical labels for NT were also detected in the caudal ventrolateral reticular formation, the locus coeruleus, and the paraventricular and lateral hypothalamic nuclei. We conclude that (1) NT or a closely related peptide is present in intrinsic neurons and multiple afferent pathways to the PBR; and (2) the axon terminals with NTLI have synaptic interactions with dendrites of intrinsic neurons and with axon terminals that may have either extrinsic or intrinsic origins.
Neuronal changes in the forebrain of mice following penetration by regenerating olfactory axons
Authors: Graziadei P. P. C. , Graziadei G. A. Monti 
Published: January 2005

AbstractFollowing total, unilateral bulbectomy in neonatal mice, the olfactory sensory axons regrow from a reconstituted population of sensory neurons, cross the lamina cribrosa, and invade the spared forebrain that has leaned forward toward the anteroventral wall of the cranial cavity. The sensory axons invade several regions of the spared forebrain, at times penetrating deeply into the brain parenchyma. These axons terminate in characteristic globose structures resembling the glomeruli of the olfactory bulb. However, they can be distinguished from the latter by the absence of periglomerular cells. These ectopic glomerular structures are formed by the commingling of the olfactory axon terminals and the dendrites of brain neurons that lie in their proximity. Previously we have established that synaptic contacts occur between the sensory axon terminals and the dendrites of the brain neurons. Our present study describes large neurons, resembling mitral cells, that expand their dendrites into the intracerebral glomeruli. These neurons are recognized by virtue of their relatively large diameter, their selective stainability with silver methods, and the unorthodox arrangement of their dendrites in comparison with the neurons of the region. Their appearance is contingent upon the presence of ectopic glomeruli. The possibility is discussed that the large argyrophilic neurons may be derived from developing neuronal elements of the brain.
Cytochemical identification of cholinergic amacrine cells in cat retina
Authors: Pourcho Roberta G. , Osman Kamal 
Published: January 2005

AbstractGolgi studies of cat retina have revealed the presence of matching subpopulations of starburst‐like amacrine and displaced amacrine cells that are morphologically similar to the cholinergic cells of rabbit retina. The displaced amacrines appear identical with the A14 cells described by Kolb et al. (Kolb, Nelson, and Mariani: Vision Res. 21:1081‐1114, 1981). In order to determine whether these cells may be cholinergic, we carried out autoradiography to localize newly synthesized (3H)acetylcholine and immunocytochemistry to demonstrate the distribution of choline acetyltransferase. Autoradiographs showed labeling in somas of both amacrine and displaced amacrine cells. Choline acetyltransferase was found in amacrine cells that ramify in sublamina a of the inner plexiform layer and in displaced amacrine cells ramifying in sublamina b. The pattern of cholinergic neurons in the cat is similar to that in other vertebrates and suggests that acetylcholine may play an important and consistent role in retinal function.
Distribution of altered hippocampal neurons and axons immunoreactive with antisera against neuropeptide Y in Alzheimer's‐type dementia
Authors: Chan‐Palay V. , Lang W. , Haesler U. , Köhler C. , Yasargil G. 
Published: January 2005

AbstractThis paper provides detailed information on the distribution of neuropeptide tyrosine (neuropeptide Y; NPY) immunoreactive neurons and fibers in the hippocampal region of eight neuropathologically confirmed cases of Alzheimer's‐type dementia (ATD) at postmortem. These neuronal networks are detected by a polyclonal antibody raised against the unconjugated peptide and controls were obtained by using liquid phase absorption immunocytochemistry. The description covers the subfields area dentata, CA3 and CA1, the subicular complex, and the entorhinal area. The hippocampal regions in which the NPY‐i neuron networks are most severely affected are the hilus, CA1, the parasubiculum, and the entorhinal cortex. Less obvious reductions occurred in CA3, subiculum, and the presubiculum. Parallel semiquantitative estimates were made of the numbers of neuritic plaques and neurofibrillary tangles in the other hippocampus of the brains in every ATD case. The areas of heaviest pathological changes by these indices are CA1 and the entorhinal cortex. The subicular complex CA3 and the area dentata are less affected. These findings show that the areas with the most severe loss of NPY‐i neurons and axons, CA1 and the entorhinal cortex, are the same as those areas most severely affected by the other indices of ATD. Thus NPY‐i networks are involved in the ATD disease process. However, other NPY‐i networks survive, in some subfields better than in others. The cumulative evidence suggests a population of hippocampal peptide neurons that are remarkably resistant in terminal neurological disease. These neurons have the capability to participate in the maintenance of minimal functioning circuits in target areas of the disease and as such hold significant links for our understanding of synaptic plasticity in disease.
Ultrastructural features of the ventromedial region of the laminar nucleus in the red‐eared turtle (Chrysemys scripta elegans)
Authors: Drakontides Anna B. , Browner Robert H. 
Published: January 2005

AbstractThe nuclei of the torus semicircularis, in particular the laminar nucleus, have been functionally implicated in sound localization, vocalization, and mating behavior. In the red‐eared turtle the ventromedial region of the laminar nucleus (containing two discrete dense cellular areas and the surrounding neuropil) was examined electron microscopically in the present study.Neuronal cell bodies in the two cellular areas were different in size, shape, cytoplasmic constitutents, and their relationship to each other. Cell bodies in the layer beneath the ependymal surface were almost always surrounded by lamellae while cell bodies in the layer above the central nucleus were in close apposition. We are speculating that cell bodies in the superficial layer may be neuroendocrine in nature. This speculation is based on the presence of lipidlike droplets within cell bodies, and previous findings indicating steroid binding and synthesis in this region in reptilian brains. Cell bodies located above the central nucleus were characteristic in that they contained lamellar bodies and extensive well‐developed Golgi regions. Closely apposed groups of these cell bodies were frequently surrounded by or in close apposition to large axonal profiles. These profiles were filled with clear core vesicles, numerous mitochondria, and clusters of small dense core particles. Synaptic contacts between large axonal profiles and cell bodies were not observed. The neuropil surrounding cell bodies of the inner layer of this region of the laminar nucleus contained glomeruli composed of a central axon surrounded, and in synaptic contact, with dendrites. Throughout the area of the laminar nucleus studied, synapses appeared to be primarily of the asymmetrical type.
Neuromuscular relationships in a muscle having segregated motor endplate zones. I. Anatomical and physiological considerations
Authors: Wines Melvin M. , Hall‐Craggs E. C. B. 
Published: January 2005

AbstractThe cranial portion of the rat anterior gracilis muscle is innervated by the obturator nerve at two discrete motor endplate zones of which the distal s supplied by well‐defined branches of the nerve. Prior to the use of this muscle in a study of motoneuron sprouting, further morphological and physiological studies have shown that its fibers vary in length but a number traverse the whole muscle or are long enough to extend through both endplate zones. The distribution of muscle fiber types is typical of a rat fasttwitch muscle, and each fiber is innervated at a single endplate. Myography showed that the spinal cord segments, which may contribute to the muscle's innervation, are L2, 3, and 4, of which L3 is constant and predominant, and that denervation of the distal endplate zone leads to a 50% reduction of the maximum isometric tension developed by the muscle.Antidromic stimulation of nerves supplying the distal endplate zone produced contraction of the proximal part of the muscle and, following similar antidromic stimulation, intracellular recordings made at proximal zone endplates showed the presence of endplate potentials. It was concluded from these data that endplates at both the proximal and distal zones can form part of the same motor unit.
Trigeminotectal and other trigeminofugal projections in neonatal kittens: An anatomical demonstration with horseradish peroxidase and tritiated leucine
Authors: McHaffie John G. , Ogasawara Kosuke , Stein Barry E. 
Published: January 2005

AbstractThe trigeminal projection to the superior colliculus in neonatal kittens was studied by using both anterograde and retrograde neuroanatomical tracing techniques. Trigeminothalamic observations also were made. In the first series of experiments, horseradish peroxidase was injected into the superior colliculus in kittens on the day of parturition and in adult cats. Retrogradely labeled cells were found throughout the contralateral sensory trigeminal complex: the greatest numbers of cells were concentrated in pars oralis, with fewer in the principal nucleus, and fewer still in pars interpolaris and pars caudialis. Thus, the distribution pattern of trigeminotectal cells in neonates is similar to that in adult animals.In the second series of experiments, we injected tritiated leucine into the rostral portion of the spinal trigeminal nucleus in neonatal kittens and adult cats and compared the laminar and spatial distribution of anterogradely transported label in the superior colliculus and thalamus. Terminal label was observed in both structures in animals as young as 1‐2 days postpartum. The label in the superior colliculus was overwhelmingly contralateral and formed a tier of discontinuous patches in the stratum griseum intermediale and, in a more diffuse manner, in the stratum griseum profundum. Most of the patches were located in the rostral 80% of the superior colliculus and were 60‐280 μm in width. Although the size of the patches was smaller in the neonates, their distribution was similar to that in adult cats. Thus, with the exception of the difference in patch size, the terminal pattern of trigeminotectal projections is essentially adultlike at birth. The dense pattern of contralateral terminal label in the arcuate division of the ventrobasal complex also was similar to that of the adult cat, as was the trigeminal projection to the supraoculomotor gray.These data indicate that the development of the spatial organization of a major ascending somatosensory pathway to the superior colliculus (and to the thalamus) is largely a prenatal event. It is likely that the further maturationn of these systems during postnatal life is limited to fine changes in axonal terminals and synaptic formation within prenatally determined terminal territories. The in utero maturation of these trigeminofugal projections is necessary to enable the newborn kitten to utilize the perioral tactile cues necessary for early orientation and suckling behaviors.