bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural analysis of synaptic relationships of intracellularly stained pyramidal cell axons in piriform cortex
Authors: Haberly Lewis B. , Presto Susan 
Published: January 2005

AbstractAxons of pyramidal cells in piriform cortex stained by intracellular injection of horseradish peroxidase (HRP) have been analyzed by light and electron microscopy. Myelinated primary axons give rise to extensive, very fine caliber (0.2 μm) unmyelinated collaterals with stereotyped radiating branching patterns. Serial section electron microscopic analysis of the stained portions of the collateral systems (initial 1–2 mm) revealed that they give rise to synaptic contacts on dendritic spines and shafts. These synapses typically contain compact clusters of large, predominantly spherical synaptic vesicles subjacent to asymmetrical contacts with heavy postsynaptic densities. On the basis of comparisons with Golgi material and intracellularly stained dendrites, it was concluded that dendritic spines receiving synapses from the proximal portions of pyramidal cell axon collaterals originate primarily from pyramidal cell basal dendrites. Postsynaptic dendritic shafts contacted closely resemble dendrites of probable GABAergic neurons identified in antibody and [3H]‐GABA uptake studies.Electron microscopic examination of pyramidal cell axon initial segments revealed a high density of symmetrical synaptic contacts on their surfaces. Synaptic vesicles in the presynaptic boutons were small and flattened.It is concluded that pyramidal cells synaptically interact over short distances with other pyramidal cells via basal dendrites and with deep nonpyramidal cells that probably include GABAergic cells mediating a feedback inhibition. This contrasts with long associational projections of pyramidal cells that terminate predominantly on apical dendrites of other pyramidal cells (Haberly and Behan: J. Comp. Neurol. 219:448–460, '83).
Three morphologically distinct types of interface develop between adult host and fetal brain transplants: Implications for scar formation in the adult central nervous system
Authors: Krüger Stefan , Sievers Jobst , Hansen Christian , Sadler Martin , Berry Martin 
Published: January 2005

AbstractThe development of the host/graft interface of cerebellar and cerebral transplants was studied 1‐60 days after operation. Grafts from fetal Wistar rats were transplanted to a cavity over the superior colliculus of adult rats by removing parts of the overlying cortex and hippocampus according to the Björklund/Stenevi technique. In sham‐operated control rats, in which a cavity was made in the brain but no graft was implanted, the parenchyma bordering the entire cavity developed a complete glial‐meningeal scar within 2 weeks after operation consisting of multilayered glial processes, a basal lamina, and fibroblasts (meningeal cells).A similar interface also developed between graft and host in the most superficial parts of the transplantation cavity. In the basal parts of the transplantation cavity, the host/graft interface consisted either of an incomplete sheet of astrocyte processes aligned in parallel to each other but without a covering basal lamina or of completely fused neuropil without any morphological signs of separation between host and transplant.It is concluded that these three zones of host/graft interface are established by differential interaction between the growing transplant and the host cicatrix. At the basal host/graft parenchymatous interface the fetal transplant interferes with the normal adult cicatrization process of the host, possibly by either releasing inhibitory factors or by preventing contact between the astroglia of the host and fibroblasts (meningeal cells). In white matter regions of the transplantation cavity, voluminous cysts developed, both in sham‐operated controls and in graft recipients, which were invaded by transplanted neurons.
Galanin immunoreactivity in hypothalamic histamine neurons: Further evidence for multiple chemical messengers in the tuberomammillary nucleus
Authors: Köhler C. , Ericson H. , Watanabe T. , Polak J. , Palay S. L. , Palay V. , Chan‐Palay V. 
Published: January 2005

AbstractBy using a specific antibody against the 29 amino‐acid peptide galanin (Gal) with light and electron microscopic immunocytochemistry, we have studied the distribution of Gal immunoreactivity in the posterior hypothalamic magnocellular neurons of the rat. In colchicine‐treated rats, a large number of Gal‐immunoreactive cells were identified within all subdivisions of the tuberomammillary nucleus. The majority of these cells are large multipolar or fusiform neurons, with long, sparsely branching dendrites. A small number project to the ventral hippocampus, as shown by experiments with the retrograde tracing of Fast Blue. Ultrastructural examination of the Gal‐immunoreactive cells confirms their indentity as magnocellular neurons, with dense deposits of immunoreaction product, particularly in small ribosomal arrays and in large, dense‐cored vesicles. Axosomatic synapses occur on these neurons. The axonal boutons synapse with asymmetric and symmetric junctions and contain small synaptic vesicles as well as numerous large, dense‐cored vesicles, which display Gal immunoreactivity. Sequential staining of thin, alternate sections with antibodies against Gal and Lhistidine decarboxylase (HDCase; EC 4.1.1.22) showed colocalization of Galand HDCase‐immunoreactivities in a majority of tuberomammillary neurons. The finding of Gal immunoreactivity within histamine‐producing neurons of the tuberomammillary nucleus adds to the multiplicity of potential neuronal messengers utilized by these cells.
Mapping of an olfactory receptor population that projects to a specific region in the rat olfactory bulb
Authors: Pedersen Patricia E. , Jastreboff Pawel J. , Stewart William B. , Shepherd Gordon M. 
Published: January 2005

AbstractAn anatomically distinct group of glomeruli, termed the modified glomerular complex (MGC), is present in the posterior dorsomedial portion of the main olfactory bulb. This region has been strongly implicated as part of the pathway that processes odor cues for suckling in neonatal rat pups. We studied the distribution pattern of olfactory receptor neurons that project to the MGC region after ionophoretic injections of WGA‐HRP into the olfactory bulbs of 12‐day‐old rat pups. HRP label was confined to an identifiable localized region in the MGC of the main olfactory bulb. Label extended over 2–7% of the glomerular sheet of the main olfactory bulb, including the MGC. Olfactory receptor neurons within the olfactory epithelium of the nasal cavity were labeled with HRP ipsilateral to the injected side. Maps constructed of the olfactory epithelium revealed that the labeled neurons occurred within topographically defined regions. Anteriorly, labeled olfactory neurons were confined to a narrow strip medial to the dorsal recess, and, more posteriorly, this strip widened medially along the septal wall and laterally onto a limited area on the nasal turbinates. Only a portion of the receptor population within a region was labeled. The boundaries between labeled and unlabeled regions were sharp. These findings support the concept that the olfactory epithelium is an anatomical mosaic in which receptors with different glomerular projections sites are intermingled. In conjunction with previous evidence on the functional specificity of the MGC, and staining of receptor neuron subgroups with monoclonal antibodies, these findings further suggest that olfactory receptor neurons form a functional mosaic within the olfactory epithelium.
Mesencephalic trigeminal sensory neurons of cat: Axon pathways and structure of mechanoreceptive endings in periodontal ligament
Authors: Byers Margaret R. , O'Connor Theresa A. , Martin Richard F. , Dong Willie K. 
Published: January 2005

AbstractWe injected 3H‐proline into cat brainstem in order to label the entire mesencephalic trigeminal nucleus (Mes‐V) for autoradiographic analysis of the size and pathways of Mes‐V sensory axons and for microscopic study of. Mes‐V receptor structure in dental tissue. Labeled sensory axons were found in the trigeminal motor and sensory tracts and roots; approximately equal numbers of axons were found in both roots. The sensory root and all three divisions of the trigeminal nerve contained larger Mes‐V axons than the motor root. Labeled Mes‐V axons were found at the ganglion in the dorsomedial (infratrochlear) branch of the ophthalmic nerve but not in the ventrolateral branch. The mean diameter of Mes‐V axons in periodontal ligament was 4.0 ± 1.9 μm compared to 7.3 ± 2.1 μm in maxillary and mandibular nerve, suggesting axonal arborization prior to innervation of ligament.Mes‐V receptors in dental tissue were confined to ipsilateral periodontal ligament close to the root apex, with greater innervation on the posterior side. Receptor incidence was moderate for most teeth; however, maxillary first and second incisors and maxillary and mandibular canines had focal areas with remarkably dense innervation. No labeled axons were found in pulp of any ipsilateral teeth, and none was found in any contralateral dental tissue.EM‐autoradiography demonstrated that Mes‐V axons form unencapsulated Ruffini‐like mechanoreceptors in periodontal ligament. The preterminal axons were small and myelinated. Neighboring bundles of unmyelinated axons and rare encapsulated endings were not labeled. The labeled mechanoreceptors branched to varying degrees among the ligament fibers; they contained numerous mitochondria and glycogen particles, as well as some vesicles and rare multivesicular bodies. They were surrounded by special Schwann cells that formed one or several layers around the ending. The endings were exposed to the basal lamina at numerous sites and occasionally extended fingers beyond the lamellar Schwann cells to contact ligament collagen.
Thalamic fiber connections in a teleost (Sebastiscus marmoratus): Visual somatosensory, octavolateral, and cerebellar relay region to the telencephalon
Authors: Ito Hironobu , Murakami Takeshi , Fukuoka Toshio , Kishida Reiji 
Published: January 2005

AbstractFiber connections of the nucleus ventromedialis thalami (VM) of Schnitzlein (J. Comp. Neurol. 118:225–267, '62) in a teleost (Sebastiscus marmoratus) were examined by means of the horseradish peroxidase (HRP) tracing method. This nucleus receives fibers from the ipsilateral telencephalon (area dorsalis pars centralis), contralateral retina, contralateral VM, ipsilateral optic tectum, ipsilateral torus semicircularis, contralateral corpus cerebelli, contralateral sensory nucleus of the trigeminal nerve, bilateral bulbospinal reticular formation, contralateral obex region, and contralateral dorsal portion of upper spinal segments. In turn, axons arising from VM terminate in the dorsal telencephalic areas (pars centralis, pars dorsalis, and pars medialis) ipsilaterally, ventral telencephalic area (pars supracommissuralis) bilaterally, nucleus prethalamicus of Meader (J. Comp. Neurol. 60:361–407, '34) bilaterally, nucleus dorsomedialis thaiami bilaterally, VM contralaterally, optic tectum bilaterally, torus semicircularis bilaterally, and nucleus lateralis valvulae ipsilaterally. Based on the cytoarchitecture and fiber connections, VM is subdivided into rostral and caudal components. The caudal part of VM in Sebastiscus is considered to be a multimodal thalamic complex that contains some cells that constitute the dorsal thalamus in other vertebrate groups.
Thickness of the basal lamina at the frog neuromuscular junction
Authors: Kuffler D. P. 
Published: January 2005

AbstractThe Schwann cell basal lamina at the frog neuromuscular junction is much thicker than previously supposed. Its thickness has been demonstrated by modifying the fixation: the nerve muscle preparation is fixed in situ without prior exposure to Ringer solution and the osmolarity of the glutaraldehyde fixative is increased to 285 mOsm. With this procedure the basal lamina is seen to be up to 1 μm thick around the Schwann cells of the nerve terminal and the preterminal axon. The thickness of the basal lamina surrounding the Schwann cells of the myelinated portion of the axons within the perineural sheath (20 nm) is not changed by this modification of fixation. The present results indicate that in addition to the ability to form myelin, other properties of the Schwann cells differ inside and outside the perineurial sheath.
Descending projections and excitation during fictive swimming in Xenopus embryos: Neuroanatomy and lesion experiments
Authors: Roberts Alan , Alford Simon T. 
Published: January 2005

AbstractWe describe the distribution of “descending” interneurons in late Xenopus laevis embryos after retrograde filling with horseradish peroxidaze via their ipsilateral, descending axons in the spinal cord. These multipolar neurons, with dendrites spread throughout the marginal zone, form a longitudinal column extending from midtrunk spinal cord into the brainstem to the level of the vagus. In the hindbrain these neurons are part of the uncrossed reticulospinal projection. They are most numerous in the caudal brainstem, their density falling by half at the eighth postotic segment.To examine their possible role in swimming we reduced the population of descending interneurons by making progressive transections of the brainstem or spinal cord at the first to fifth postotic segments: These led to progressive reduction in the initial frequency of fictive swimming in immobilized embryos, even when the brainstem was divided sagittally. Transecting the spinal cord at the fourth postotic segment did not reduce initial frequency rostral to the lesion. The effects of these lesions on the duration of fictive swimming episodes were similar.The results suggest (1) that descending interneurons could provide excitatory drive during swimming and (2) that some reticulospinal and spinal interneurons may form single homogenecus populations.
GABAergic input to cholinergic forebrain neurons: An ultrastructural study using retrograde tracing of HRP and double immunolabeling
Authors: Źborszky L. , Heimer L. , Eckenstein F. , Leranth C. 
Published: January 2005

AbstractAmygdalopetal cholinergic neurons in the ventral pallidum were identified by combining choline acetyltransferase (ChAT) immunohistochemistry with retrograde tracing of horseradish peroxidase (HRP) following injections of the tracer in the basolateral amygdaloid nucleus. Although ChAT‐positive terminals were identified in the ventral pallidum, they were never seen in contact with either immunonegative or ChAT‐positive amygdalopetal neurons; In material, in which immunostaining against glutamic acid decarboxylase (GAD), the synthesizing enzyme for GABA was combined with retrograde tracing of HRP from the basolateral amygdaloid nucleus, GAD‐positive terminals were seen to contact immunonegative amygdalopetal neurons. In addition, when sections of the rostral forebrain were processed, first to preserve and identify the transported HRP, and then were sequentially tested for both ChAT and GAD immunohistochemistry with the immunoperoxidase reaction for both tissue antigens, GAD‐immunopositive terminals were seen to make synaptic contacts with cholinergic amygdalopetal neurons. These results suggest that amygdalopetal, presumably cholinergic, neurons receive GAD‐positive terminals. In separate experiments using immunoperoxidase for ChAT and ferritin‐avidin for GAD labeling, we confirmed the presence of GAD‐containing terminals on cholinergic neurons. In addition, cholinergic terminals were seen in synaptic contact with GAD‐positive cell bodies. These morphological studies suggest that direct GABAergic‐cholinergic and cholinergic‐GABAergic interactions take place in the rostral forebrain.
The dopaminergic innervation of the ventral striatum in the rat: A light‐ and electron‐microscopical study with antibodies against dopamine
Authors: Voorn P. , Jorritsma‐Byham B. , Van Dijk C. , Buijs R. M. 
Published: January 2005

AbstractDopamine (DA) in the dorsal and ventral striatum is associated with different aspects of locomotor activity control. The ventral striatum may form an interface between the limbic system and the extrapyramidal motor system. The distribution of dopaminergic fibers in this interface position was studied in detail with a method applying antibodies against DA. Furthermore, the ultrastructural morpholohy of the DA fibers was examined by means of immuno‐electron microscopy. The results show that DA immunoreactivity is distributed over the ventral striatum in a highly compartmentalized fashion. In jthe dorsal striatum few compartments were found. The DA fibers in the ventral striatum establish mainly symmetric synaptic contacts, preferably with dendritic shafts and spines. The results are discussed in relation to previous data concerning the light and electron‐microscopic identification of catecholaminergic fibers in the ventral and sorsal striatum.
Topographic representation of lower and upper teeth within the trigeminal sensory nuclei of adult cat as demonstrated by the transganglionic transport of horseradish peroxidase
Authors: Shigenaga Y. , Suemune S. , Nishimura M. , Nishimori T. , Sato H. , Ishidori H. , Yoshida A. , Tsuru K. , Tsuiki Y. , Dateoka Y. , Nasution I. D. , Hosoi M. 
Published: January 2005

AbstractTransganglionic transport of horseradish peroxidase‐wheat germ agglutinin conjugate (HRP‐WGA) entrapped in hypoallergenic polyacrylamide gel was used to study the patterns of termination of primary afferents that innervate the lower and upper tooth pulps within the trigeminal sensory nuclear complex (TSNC). HRP injections were made into the inferior and superior alveolar nerves in order to compare the central projections of the whole nerve with those from tooth pulps. In addition, the relationship between the distribution of the trigeminothalamic tract cells and the projection sites of the tooth pulp afferents was investigated by injecting HRP into the posterior ventral thalamus. HRP‐labeled tooth pulp afferent fibers innervating the lower and upper teeth projected to the subnucleus dorsalis (Vpd) of pars principalis, the rostrodorsomedial part (Vo.r) and nucleus dorsomedialis (Vo.dm) of pars oralis, the medial regions of pars interpolaris, and laminae I, II, and V of pars caudalis. Terminal fields of the lower tooth pulp afferents formed a rostrocaudally running, uninterrupted column from the midlevel of Vpd to the caudal tip of caudalis. In contrast, the column of termination of upper tooth pulp afferents was discontinuous at the Vpd/Vo.r transition, and ended at the more rostral level of the caudalis than that of the lower tooth pulp afferents. The representation of the lower and upper teeth in the TSNC was organized in a somatotopic fashion which varied from one subdivision to the next, although terminal zones of the inferior and superior alveolar nerves overlapped within the Vo.r, Vo.dm, and dorsomedial part of rostral pars interpolaris. The lower and upper teeth were represented in the Vpd, Vo.r, Vo.dm, medial region of pars interpolaris, and laminae I, II, and V, in a ventrodorsal or caudorostral, dorsoventral, lateromedial, dorsoventral, and mediolateral or dorsomedial‐ventrolateral sequence, respectively. The smaller, more focal terminal areas of the teeth contrasted sharply with more extensive terminal fields of the alveolar nerves. The HRP injections within the thalamus indicated that neurons in Vpd, the caudal pars inter polaris, and laminae I/V of caudalis, which are subdivisions of TSNC that receive pulpal projections, sent their axons to the ipsilateral and contralateral posterior ventral thalamus. The present data reconfirmed our previous suggestion (Shigenaga et al.: J. Comp. Neurol. 243:388–408, '86a, J. Comp Neurol. 244:1–18, '86b) of a functional segregation among the cytoarchitectonically different zones of the TSNC, and further suggested that the sub nucleus dorsalis of the principal nucleus in addition to the caudal parts of interpolaris and laminae W of the caudalis plays an important role in the relay of pain from the oral regions.
Neuropeptide Y localization in the rat amygdaloid complex
Authors: Gustafson Eric L. , Card J. Patrick , Moore Robert Y. 
Published: January 2005

AbstractNeuropeptide Y (NPY)‐, avian pancreatic polypetide (APP)‐, and molluscan cardioexcitatory peptide (FMRF)‐like immunoreactivity in the amygdaloid complex of the rat was investigated immunohistochemically. The distribution of each of these peptides within the amygdala is identical and cross‐blocking studies indicate that all three antisera recognize the NPY antigen. Morphologically distinct populations of NPY immunoreactive neurons are differentially distributed in the medial amygdaloid nucleus and at the base of the stria terminalis. Dense plexuses of immunoreactive axons are present in the medial third of the central nucleus and in the dorsal half of the medial nucleus, with light to moderate fiber plexuses present in the lateral and basolateral nuclei and scattered axons present throughout the remainder of the amygdala. The distribution and appearance of NPY immunoreactive plexuses in the amygdala is similar to that described previously for noradrenergic axons arising from brainstem cell groups (Fallon, Koziell, and moore: J. Comp. Neurol. 180:509–532, '78). However, injections of the noradrenergic neurotoxin 6‐hydroxydopamine into the amygdala result in a complete loss of dopamine‐beta‐hydroxylase (DBH) immunoreactivity in the amygdala and surrounding cortex but leave much of the NPY immunoreactive plexus intact. Similarly, lesions of the locus coeruleus deplete DBH immunoreactivity, leaving NPY‐like immunoreactivity in the amygdala unaffected. These results indicate that much of the NPY immunoreactive plexus observed in the amygdala does not arise from brainstem sources in which NPY and noradrenaline are colocalized. Lesions of the stria terminalis of medial nucleus have no observable effect on the density or distributiion of NPY immunoreactive terminal fields in the basal forebrain and hypothalamus, suggesting that immunoreactive neurons in the amygdaloid complex do not contribute significantly to this innervation.