bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitory axoaxonal and neuromuscular synapses in the crayfish opener muscle: Membrane definition and ultrastructure
Authors: Govind C. K. , Atwood H. L. , Pearce Joanne 
Published: January 2005

AbstractThe specific inhibitory motoneuron to the crayfish (Procambarus clarkii) opener muscle provides neuromuscular synapses to the muscle fibers and axoaxonal synapses to the excitatory motor nerve terminals. Freeze fracture of the membrane in both types of synapses show that the presynaptic active zone consists of clusters of large particles (putative calcium channels), which are often encircled by large depressions representing fused synaptic vesicles on the internal leaflet or P face of the presynaptic membrane. Corresponding pits and protrusions mark the external leaflet or E face of the presynaptic membrane. The postynaptic receptor‐bearing surface, characterized for neuromuscular synapses only, consists of rows of particles on both leaflets of the muscle membrane. The organization differs from that seen at excitatory synapses where particles occur only on the E‐face leaflet. Serial thin sections of nerve terminals reveal that neuromuscular synapses are significantly larger in proximal fibers than in their central counterparts and support a greater number of presynaptic dense bars (active zones). Axoaxonal synapses also show regional differences; almost three times as many occur in the proximal region compared with the central region. Most synapses possess a single dense bar. The majority of synapses formed by the inhibitory axon are neuromuscular; a minority are axoaxonal. The latter occur in various locations along the excitatory nerve terminals as well as on branches of the axon itself. This preterminal or, “off‐shore” location could act to cut off entire populations of excitatory synapses or reduce the amplitude of the preterminal action potential. © 1995 Willy‐Liss, Inc.
The efferent projections of the periaqueductal gray in the rat: A Phaseolus vulgaris‐leucoagglutinin study. II. Descending projections
Authors: Cameron Adrian A. , Khan Iqbal A. , Westlund Karin N. , Willis William D. 
Published: January 2005

AbstractThe descending projections of the periaqueductal gray (PAG) have been studied in the rat using the anterograde tracer Phaseolus vulgaris‐leucoagglutinin. The tracer was injected into the dorsolateral or ventrolateral subdivisions of the PAG at rostral or caudal sites. It was found that the patterns of the descending projections of the rostral and caudal parts of the dorsolateral PAG were the same and that the patterns of the descending projections of the rostral and caudal parts of the ventrolateral PAG were the same. However, the patterns of projections of the dorsolateral and ventrolateral PAG subregions were substantially different. These results suggest that the dorsolateral and ventrolateral parts of the PAG are organized into longitudinal columns that extend throughout the length of the PAG. The axons of PAG neurons descended through the pons and medulla via two routes. A small fiber bundle was present in the periaqueductal gray and in the periventricular area. This bundle distributed fibers and terminals locally within the periaqueductal gray and in the locus coeruleus and Barrington's nucleus. A larger bundle had a diffuse arrangement in the pontine reticular formation, however, and it had a more restricted distribution in the medulla, where it occupied a position dorsolateral to the pyramid. This bundle supplied structures in the pontine and medullary tegmentum. The dorsolateral column preferentially supplied the locus coeruleus, subcoeruleus, the gigantocellular nucleus pars alpha, the rostral part of the paragigantocellular nucleus, and the region of the A5 noradrenergic cell group. The ventrolateral column preferentially supplied the nucleus raphe magnus, the caudal part of the lateral paragigantocellular nucleus, and the rostroventrolateral reticular nucleus. © 1995 Willy‐Liss, Inc.
Phaseolus vulgaris –leucoagglutinin tracing of commissural fibers to the rat dentate gyrus: Evidence for a previously unknown commissural projection to the outer molecular layer
Authors: Deller T. , Nitsch R. , Frotscher M. 
Published: January 2005

AbstractNumerous studies have shown a lamina‐specific termination of commissural fibers to the dentate gyrus in the inner molecular layer. However, the exact course and arborization pattern of individual fibers remained unknown. In this study, the commissural fiber tract to the dentate gyrus of the rat has been studied using the anterograde tracer Phaseolus vulgaris ‐leucoagglutinin (PHA‐L), which labels individual axons and their collaterals. Following iontophoretic application of the tracer, anterogradely labeled fibers were followed through the posterior basal fornix and medial fimbria where they formed a dense fiber bundle. Labeled fibers then entered the dentate gyrus close to the medial blade of the granule cell layer where they separated and traversed the hilus. Only in those cases where the injection also involved CA3 pyramidal cells could axons arborizing in the hilus be observed. Typically, fibers that continued into the molecular layer did not arborize in the hilus. Upon their entrance into the molecular layer, these fibers changed direction, gave off several collaterals, and followed a new path parallel to the granule cell layer where they preferentially formed en passant contacts. These commissural fibers to the inner molecular layer terminated in a wide septotemporal (longitudinal) extension. However, a considerable number of fibers reached the outer molecular layer where some of them formed extensive arborizations. Moreover, these commissural fibers to the outer molecular layer appeared to be restricted to the hippocampal lamella, corresponding to the level of the contralateral injection site. These data suggest the existence of three commissural projections to the rat dentate gyrus: (1) commissural fibers to the hilus arising from CA3 neurons, (2) commissural fibers to the inner molecular layer, and, (3) commissural fibers to the outer molecular layer. © 1995 Wiley‐Liss, Inc.
Heterogeneous topographical distribution of the striatonigral and striatopallidal neurons in the matrix compartment of the cat caudate nucleus
Authors: Desban Marcel , Gauchy Christian , Glowinski Jacques , Kemel Marie‐Louise 
Published: January 2005

AbstractThe topographical organization of the striatonigral projection was investigated in the cat by comparing the localization and the intensity of labelling of retrogradely labelled cells in the caudate nucleus following one or multiple injections of horseradish peroxidase‐wheat germ agglutinin into the center or along the rostrocaudal axis of the substantia nigra pars reticulata. Second, the localizations of retrogradely labelled striatopallidal neurons and of clusters of aggregated striatonigral neurons (as outlined by the transportof 14C‐material) were compared in cats that received four horseradish peroxidase‐wheat germ agglutinin injections into the internal segment of the globus pallidus and three nigral injectionsof 14C‐amino acids into the substantia nigra pars reticulata. Two types of striatonigral neurons located predominantly within the matrix compartment were identified: poorly collateralized aggregated cells distributed in clusters and more numerous collateralized cells distributed outside the clusters. In addition, two cell types were distinguished within each cluster of aggregated neurons. Those innervating the center of the substantia, nigra pars reticulata were observed after a single nigral injection of the tracer, whereas those projecting to distinct sites of the substantia nigra pars reticulata along a rostrocaudal axis were observed only after multiple injections. Striatal neurons innervating the internal segment of the globus pallidus were heterogeneously distributed predominantly within the matrix but outside the clusters of aggregated striatonigral neurons. Together, these results provide further evidence for the heterogeneity of the matrix and for the complexity of matrix striatonigral connections that send both diverging and converging signals to the substantia nigra pars reticulata. © 1995 Wiley‐Liss, Inc.
The retinohypothalamic tract originates from a distinct subset of retinal ganglion cells
Authors: Moore Robert Y. , Speh Joan C. , Patrick Card J. 
Published: January 2005

AbstractThe retinal ganglion cells giving rise to retinohypothalamic projections in the rat were identified using retrograde transport of horseradish peroxidase (HRP) or Fluoro Gold injected into the suprachiasmatic nucleus (SCN), and using transneuronal transport of the Bartha strain of the swine herpesvirus (PRV‐Bartha). When PRV‐Bartha is injected into one eye, it is taken up by retinal ganglion cells, replicated, transported to axon terminals in the SCN, and released. There the virus may take one, or both, of two paths to retinal ganglion cells in the contralateral eye: (1) uptake by SCN neurons, replication, and release from the neurons with uptake and retrograde transport in retinal afferents originating in the contralateral retina; (2) transneuronal passage through axo‐axonic appositions between retinal afferents in the SCN with subsequent retrograde transport of virus to the contralateral retina. The ganglion cells thus labeled are a homogeneous population of small neurons (mean diameter, 12.8 ± 2.2 μm an mean area, 81.8 ± 21.8 μm2) with sparsely branching dendrites that are widely distributed over the retina. This population is best identified when virus labeling of retinal projections in areas beyond the hypothalamus is eliminated by lateral geniculate lesions that transect the optic tract at its entry into the geniculate complex. The same population is labeled with retrograde tracers but, with both HRP and Fluoro Gold, other ganglion cells are labeled, presumably from uptake by fibers of passage, indicating that the virus is a more reliable marker for ganglion cells giving rise to retinohypothalamic projections. The ganglion cells identified correspond to a subset of type III, or W, cells. © 1995 Wiley‐Liss, Inc.
NADPH‐Diaphorase in the central nervous system of the tench (tinca tinca L., 1758)
Authors: Arévalo R. , Alonso J. R. , García‐Ojeda E. , Briñón J. G. , Crespo C. , Aijón J. 
Published: January 2005

AbstractThe distribution and morphological characterization of nicotinamide adenine dinucleotide phosphate‐diaphorase (ND)–positive cells and fibers in the tench central nervous system was mapped by using a direct histochemical method. This enzyme was observed in specific cell populations throughout all main divisions of the tench brain.In the telencephalon, we found strongly labeled olfactory fibers, as well as positive cells and fibers in the area ventralis of the telencephalic lobes. Positive staining was observed in the following diencephalic nuclei: nucleus preopticus magnocellularis pars magnocellularis, nucleus recessus lateralis, nucleus recessus posterioris, nucleus posterior tuberis, and nucleus diffusus torus lateralis, as well as small cells with a diffuse distribution surrounding the diencephalic ventricle. In the mesencephalon, heavily stained ND‐positive neurons were observed in the nucleus fasciculi longitudinalis medialis, nucleus nervi oculomotorius, and nucleus nervi trochlearis. In the hindbrain the most evident staining was observed as large neurons located in the nuclei of the cranial nerves, scattered positive cells located between the negative fibers of the cranial nerves, and in the nucleus fasciculi solitari. Finally, in the spinal cord, ND‐positive cells and fibers were mainly located in the ventral horn.This distribution of ND labeling in the brain of the tench is significantly different from previous data on ND activity in the brain of terrestrial vertebrates and does not correlate with the presence and distribution patterns of several neurotransmitters and neuroactive substances in the teleost brain. © 1995 Wiley‐Liss, Inc.
Morphology of ganglion cells in the neotenous tiger salamander retina
Authors: Toris Carol B. , Eiesland Jodi L. , Miller Robert F. 
Published: January 2005

AbstractThe morphology of retinal ganglion cells in the neotenous tiger salamander (Ambystoma tigrinum) was analyzed with the aid of morphometric techniques to determine the diversity of cell types and to evaluate the widely held notion that this form of Ambystoma has a simple retina, with little variance among its cell morphologies. Single‐cell staining was achieved through retrograde labeling with horseradish peroxidase injected around the optic nerve sheath followed by a period of several days before tissue processing; 83 well‐labelled cells with axons were studied in detail with light microscopy and a computer‐aided reconstruction system. Five different morphological cell classes were devised based on broad morphometric criteria such as the dendritic area of influence; the number, length, and complexity of dendritic branches; and the amount of overlap between neighboring dendrites. These classes included small simple, small complex, medium simple, medium complex, and large cells. In addition, a class of cells with numerous varicosities among the dendrites was separately analyzed. These swellings did not stain for catecholamines.Based on optical determinations of the dendritic sublamination pattern within the inner plexiform layer, presumed On‐Off cells are present in all subclasses, whereas On cells predominate in the smaller cell groups. Presumed Off cells are well represented in the large field units, although the small total number of cells in this latter class leads to uncertainty regarding the significance of this observation. The diversity of ganglion cell morphology revealed in the present study argues against the assumption that the neotenous tiger salamander has a simple retina, with a relatively invariant set of ganglion cells. On the contrary, it appears that this aquatic form shows morphological diversity in the retinal ganglion cell population rivaling that reported for other vertebrates, including mammals. A functional role for the different cell classes is briefly considered. © 1995 Wiley‐Liss, Inc.
Spinal projection neurons to the laterodorsal pontine tegmental nucleus: Relationship to preganglionic neurons and nitric oxide synthase
Authors: Hamilton Murray O. , Papka Raymond E. , O'donoghue Daniel L. , Vaidya Atul M. , Williams Sonya J. , Poff Clifton R. D. , McNeill Daniel L. 
Published: January 2005

AbstractThe region of the rat sacral parasympathetic nucleus (SPN) contains distinct subpopulations of neurons that project supraspinally or are preganglionic neurons. Some preganglionic neurons in the SPN serve as the motor outflow for urinary bladder contraction; other neurons in the SPN project to regions of the rostral pons that subserve micturition reflexes. Previous studies utilizing immunohistochemistry or staining for nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) have demonstrated that numerous neurons in the SPN contain nitric oxide synthase (NOS), the enzyme for nitric oxide synthesis. Thus, the objectives of this study were to determine (1) the distribution of neurons in the region of the SPN that project to the laterodorsal tegmenturn (LDT) of the pons, (2) whether spinal neurons projecting to a peripheral autonomic ganglion also project to the LDT, and (3) whether NOS or NADPH‐d is present in LDT projection neurons. Preganglionic neurons were identified by injecting the retrograde tracer fluorogold (FG) into the major pelvic ganglion (MPG). Supraspinally projecting neurons were identified by injecting the retrograde tracer fast blue (FB) into the LDT. Numerous FB‐labeled neurons were present in the ipsi‐ and contralateral SPN and were immediately dorsal to FG‐labeled preganglionic neurons. Neurons containing both tracers were not observed. Approximately 20% of preganglionic neurons, but no LDT projection neurons, were reactive for NOS and NADPH‐D. These data suggest that the region of the SPN is a site for distinct subpopulations of neurons that project to the LDT and to the MPG and that NOS is contained in some preganglionic neurons, but is not a marker for LDT projection neurons. © 1995 Wiley‐Liss, Inc.
Development of the longitudinal projection patterns of lumbar primary sensory afferents in the chicken embryo
Authors: Eide Anne Lill , Glover Joel C. 
Published: January 2005

AbstractThe literature on the anatomical organization of primary sensory afferents, though extensive, contains relatively little information about the longitudinal extent of the central collateral projections. Our understanding of intersegmental sensorimotor integration in the spinal cord and of the developmental mechanisms that establish its underlying circuitry could be significantly enhanced by a more complete description of these projections. To address this issue from a developmental perspective, we labeled the central projections of lumbar primary afferents in fixed preparations of the chicken embryo with the lipophilic tracer DiI. At late embryonic stages, the afferent projections had the following characteristics: Primary afferents originating from a single lumbar dorsal root ganglion bifurcated to project longitudinally in the dorsal funiculus or Lissauer's tract. Dorsal funiculus axons extended up to seven segments caudally and to at least ten segments rostrally, whereas axons in Lissauer's tract extended up to seven segments in each direction. Collaterals branched off the longitudinal axons over a range of about seven segments in each direction. Within this range, collaterals to specific terminal fields exhibited more restricted ranges.The development of these longitudinal patterns during earlier embryonic stages was followed from the time the afferents first reached the neural tube on day 4 of embryogenesis. The longitudinal axons lengthened as a single bundle up to day 10, with medial axons consistently longer than lateral axons. After day 10, the longitudinal axons were segregated into the dorsal funiculus and Lissauer's tract. Collaterals sprouted after about 2 days of longitudinal axon growth, by which time the axons had extended several segments in each direction. The segmental range over which collaterals were present reached a maximum of 20 segments at day 10. Collaterals to the different terminal areas differed in their segmental ranges already by this time. After day 10, the total segmental range of collaterals decreased to the stable level of about seven segments in each direction, which is characteristic of late‐stage embryos. © 1995 Wiley‐Liss, Inc.
Monosynaptic input from Leu5‐enkephalin‐immunoreactive terminals to vagal motor neurons in the nucleus ambiguus: Comparison with the dorsal motor nucleus of the vagus
Authors: Milner T. A. , Okada J. , Pickel V. M. 
Published: January 2005

AbstractVagal motor neurons in the rat dorsal motor nucleus of the vagus (DMN) are known to receive direct synaptic input from enkephalin‐containing terminals. We examined (1) whether the vagal motor neurons within the nucleus ambiguus (NA) also received monosynaptic input from enkephalin‐immunoreactive terminals and (2), if so, whether their ultrastructural relations differed from those in the DMN. In both regions, terminals containing Leu5‐enkephalinlike immunoreactivity (LE‐LI) were examined in relation to motor neurons identified by retrograde transport of wheat germ‐agglutinated horseradish peroxidase (WGA‐HRP) applied to the cut end of the cervical vagus nerve in single sections of the medulla oblongata of adult rats. By light microscopy, the most significant overlap between varicose processes with LE‐LI and WGA‐HRP‐containing neurons was seen in the rostral compact portion of the NA and the DMN at the level of the obex. Thus, only these regions were examined by electron microscopy. The most distinguishing ultrastructural feature of WGA‐HRP‐labeled neurons in the NA compared to the DMN was their higher incidence of nonsynaptic appositions with other neurons. In both the NA and the DMN, terminals with LE‐LI formed primarily symmetric synapses on smaller (presumably distal) dendrites; many of these dendrites, as well as most target perikarya, contained WGA‐HRP. Additionally, in the compact portion of the NA compared to the DMN (1) multiple LE‐labeled terminals more frequently contacted single perikarya or dendrites and (2) single terminals with LE‐LI more commonly showed two contacts or active zones and contained more abundant LE‐immunoreactive large (80–100 nm) densecore vesicles (dcvs). In contrast to small (40–50 nm), clear vesicles, which were usually aggregated near active zones, the immunoreactive dcvs were usually located near glial processes distal to these zones. These results indicate that enkephalin immunoreactivity is intensely localized to dcvs within terminals that may have direct inhibitory (symmetric synapses) actions on vagal motor neurons in both the compact portion of the NA and the DMN. Moreover, because numbers of dcvs and active zones have been equated with synaptic strength, our findings suggest enhanced potencies of enkephalin‐immunoreactive terminals in the compact portion of the NA. Our findings support a prominent role for enkephalin in the coordinated activity of esophageal motor neurons located in the compact portion of the NA. © 1995 Wiley‐Liss, Inc.
Postnatal development and synaptic connections of hilar mossy cells in the hippocampal dentate gyrus of rhesus monkeys
Authors: Seress László , Ribak Charles E. 
Published: January 2005

AbstractMossy cells of the hippocampal dentate gyrus were analyzed through postnatal development. At birth, a few thorny excrescences were found on the proximal dendrites of mossy cells, whereas distal dendrites displayed pedunculate spines. Thorny excrescences increased in number and complexity until the third month. After that age, the complexity of thorny excrescences is so great that an increase in spine density can be seen only in electron microscopic preparations. An increase in the number of pedunculate spines per unit length of distal dendrite was detected via light microscopy during the first 9 postnatal months. The somata and dendrites of mossy cells displayed adult‐like characteristics after the ninth postnatal month.Mossy fiber terminals at birth frequently displayed immature ultrastructural characteristies and formed synapses with dendritic shafts and spines. At later postnatal ages and in adults, axospinous synapses were found almost exclusively. This is consistent with the postnatal development of the complex spines of the mossy cells.Axons of mossy cells were generally confined to the hilus in our 150 ‐μm‐thick sections, where they gave rise to several collaterals. The axon terminals from these collaterals formed asymmetric synapses with dendrites and dendritic spines in the hilar region of the dentate gyrus. These data provide the first anatomical evidence that hilar mossy cells of the primate dentate gyrus have excitatory projections similar to their equivalent cell type in subprimates.The present study indicates that mossy cells of the dentate gyrus are in a more advanced stage of development at birth and mature faster than similar neurons of the human hippocampus. This may represent a faster maturation of hippocampal circuitry in nonhuman primates compared to that in the human.