bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of motoneurons supplying dorsal suboccipital and intervertebral muscles in the cat neck
Authors: Gordon D. C. , Richmond F. J. R. 
Published: January 2005

AbstractMultiple labelling methods were used to examine the topographical organization of motoneurons supplying the suboccipital muscles, rectus capitis posterior (RCP) and obliquus capitis inferior (OCI); the intervertebral muscles, spinalis dorsi (SD) and semispinalis cervicis (SSC); and the dorsal extensor biventer cervicis (BC). Muscle nerves were isolated, cut, and exposed in the same animal to one of three different retrograde tracers, Fluorogold, Fast Blue, and horseradish peroxidase. Motoneurons supplying suboccipital muscles were found to be located in the rostral two cervical segments. The RCP motor nucleus was confined to C1 and the caudal brainstem, whereas the OCI nucleus usually originated in mid‐C1 and extended caudally as far as mid‐C2. Most motoneurons supplying OCI and SD were concentrated in the deepest part of the ventral horn, but some cells were found in the commissural region, the contralateral ventral horn, the dorso‐medial aspect of the ipsilateral ventral horn, and the ventromedial white matter. Cells supplying the functional extensor RCP were intermingled with those supplying the turning muscle OCI, although a gradient in mediolateral distribution was detected. Motoneurons supplying the intervertebral muscles SD and SSC were found caudal to C3. Within the ventral horn, they occupied locations similar to those occupied by suboccipital motoneurons in C1 and C2. The cell column for intervertebral motoneurons was just medial to that of BC and some cells supplying SD and SSC were found in the territory occupied by BC motoneurons. Motoneurons supplying intervertebral and suboccipital muscles had unimodal diameter spectra, and most cells had mean equivalent diameters smaller than 35 μm.
Distribution of motoneurons supplying cat sartorius and tensor fasciae latae, demonstrated by retrograde multiple‐labelling methods
Authors: Gordon D. C. , Loeb G. E. , Richmond F. J. R. 
Published: January 2005

AbstractSartorius (SART) and tensor fasciae latae (TFL) in the cat hindlimb are functionally heterogeneous muscles with regions that differ in their skeletal actions and electromyographic recruitment during normal activity. The topographical organization of motoneurons supplying different regions of SART or TFL has been investigated by exposing cut nerve branches supplying different peripheral territories to a combination of retrograde tracers, including Fast Blue (FB), Fluorogold (FG), and horseradish peroxidase (HRP). Motoneurons supplying medial, central, and anterior regions of SART were intermixed extensively throughout a single columnar nucleus located in the ventrolateral part of segments L4 and L5. Within this column, motoneurons supplying medial SART tended to lie more rostrally than those supplying anterior regions, but the gradient was modest and showed some cat‐to‐cat variation. Two major branches entered anterior SART at different proximodistal levels. When these two branches were exposed to different tracers, most motoneurons contained a single tracer; only a few double‐labelled cells were apparent. The labelling suggests that anterior SART may contain two separate, in‐series divisions of motor units. In TFL, motoneurons supplying nerve branches to posterior, central, and anterior parts of the muscle were intermingled indiscriminately in a single ventrolateral cell column in L6 and rostral L7. These results suggest that topographical organization in lumbar motor nuclei does not always reflect the highly ordered biomechanical and functional specialization evident in the peripheral organization of the muscles themselves.
Postnatal development of the noradrenergic projection from locus coeruleus to the olfactory bulb in the rat
Authors: McLean John H. , Shipley Michael T. 
Published: January 2005

AbstractNorepinephrine (NE) may play a role in the developing brain by modulating synaptic plasticity during critical periods of circuit formation (Kasamatsu and Pettigrew, 1976; 1979; Bear and Singer, 1986). In the olfactory bulb, NE input from the locus coeruleus (LC) appears to be necessary for the newborn rat to form a learned odor preference (Sullivan and Leon, 1986; Wilson and Leon, 1988; Sullivan et al., 1989). However, little is known about the development of NE innervation of the olfactory bulb. Thus, it is not clear how the maturation of the LC projection to the bulb correlates with the formation of olfactory bulb circuits during the period when NE modulates early olfactory learning. In this study, the postnatal development of the NE input from the LC to the main and accessory bulbs was characterized with tract tracing, immunocytochemistry, and quantitative image analysis methods.By birth there is already a substantial input to the olfactory bulb from the LC; as many as 200 LC neurons can be retrogradely labelled with wheatgerm agglutinin‐horseradish peroxidase injection in the olfactory bulb. This compares with an estimated 400–600 neurons labelled by similar procedures in adult rats (Shipley et al., 1985).In order to study the development of NE fibers innervating the olfactory bulb, immunocytochemistry with antibodies to dopamine‐β‐hydroxylase was employed. Image analysis was used to facilitate visualization and to quantitate the development of fiber densities. At birth, immunocytochemically labelled NE fibers were identified in all layers of the main and accessory olfactory bulb. The innervation was strongly preferential for infraglomerular layers at all stages of postnatal development. The fibers were densest in the internal plexiform and granule cell layers, less dense in the external plexiform layer, and sparse in the glomerular layer. The density of the fibers increased during development. There were no significant shifts in the relative distribution of the fibers in different layers of the bulb during development. This consistent laminar innervation by NE fibers suggests that if these fibers have a developmental role, their influence is probably limited to neuronal elements in inframitral cell layers.
In situ hybridization analysis of the FMRFamide neuropeptide gene in Drosophila. I. Restricted expression in embryonic and larval stages
Authors: Schneider Lynne E. , O'Brien Martha A. , Taghert Paul H. 
Published: January 2005

AbstractWe have used in situ hybridization techniques to describe the cellular distribution of transcripts from a Drosophila gene that encodes multiple FMRFamide‐related neuropeptides. The Drosophila FMRFamide gene consists of two exons and is expressed predominantly as a ∼ 1.7 kb RNA throughout postembryonic stages (Nambu et al., '88; Schneider and Taghert, '88, '90). We used exon‐specific oligonucleotide probes to assay transcription in both embryonic and larval stages and found a pattern of hybridization signals that was restricted to the central nervous system and, within that tissue, was cell‐specific. The pattern included 36 distinct signals distributed throughout both the brain and segmental nerve cord (ventral ganglion). These observations suggest that the cell‐specific pattern of FMRFamide‐like neuropeptide expression in the Drosophila CNS (White et al., '86; Taghert and Schneider, '90) is due to the restricted expression of specific gene transcripts. The results also indicate that, with few exceptions, all previously identified FMRFamide‐immunoreactive neurons in Drosophila larvae express FMRFamide gene transcripts. The 36 hybridization regions of the CNS could be divided into three categories, based on their signal intensities (strong, moderate, and weak). The differences in intensity were reproducible and suggest that steady‐state levels of specific neuropeptide RNA differ among individual neurons. The two exon‐specific probes produced patterns that were indistinguishable both in pattern and in intensity. This result supports the previous conclusion that the one detectable FMRFamide transcript contains both exons (Schneider and Taghert, '90). A single identifiable signal was detected during embryogenesis (beginning at stage 16), but the mature complement of signals was not fully established until the final larval stages.
Fine structure and synaptic architecture of HRP‐labelled primary afferent terminations in lamina IIi of the rat dorsal horn
Authors: Cruz F. , Lima D. , Zieglgänsberger W. , Coimbra Antonio 
Published: January 2005

AbstractThe fine structure and synaptic architecture of the afferent terminations in dorsal horn lamina II are studied using a combined light and electron microscopic procedure after anterograde labelling with horseradish peroxidase. Vibratome parasagittal sections, stained with heavy metal intensified diaminobenzidine after tracer application to the dorsal roots, were flat‐embedded in Epon. The five types of labelled terminal arbors occurring in lamina IIi (Cruz et al., '87: J. Comp. Neurol. 261:221–236) were drawn and relocated in 5‐μm sections cut serially from the thick sections. Ultrathin sections were then cut from the 5‐μm sections so that the terminal fibers and swellings observed in the light microscope could be traced in the electron microscope. The flame‐shaped arbors arose from fine myelinated stem fibers. Terminal strands generated large oval central terminals of type II synaptic glomeruli (CII), which established frequent axoaxonal contacts. Similar terminals have been labelled in the cat after tracer injections into hair‐follicle fibers (Réthelyi et al., '82: J. Comp. Neurol. 207:381–393). The other four plexuses arose from unmyelinated stem fibers. The swarms of ultrafine boutons consisted of extremely thin terminal fibers generating very small, round, or polygonal glomerular terminals containing tightly packed agranular synaptic vesicles of variable size and one mitochondrion at best. The terminal strands of the bouquet plexus bore long and scalloped central varicosities of type I synaptic glomeruli (CI) with pleomorphic agranular vesicles and a relative abundance of dendroaxonal contacts. These features, together with the location in dorsal lamina IIi, suggest their belonging to the fluoride resistant acid phosphatase (FRAP)‐reactive population. The boutons of the undulating fibers and those of the lateral plexus were, like those of the bouquets, scalloped and elongated rostrocaudally (CI), but contained a few large granular vesicles. The occurrence of the swarm, undulating, and lateral plexuses in ventral lamina IIi, which seems to lack FRAP or peptidergic terminals, suggests an origin from other, still unidentified neurochemical populations of fine primary afferents.
Increase in a focal population of juxtaglomerular cells in the olfactory bulb associated with early learning
Authors: Woo Cynthia C. , Leon Michael 
Published: January 2005

AbstractYoung rats learn to approach an odor that had been experienced in the presence of reinforcing tactile stimulation. Subsequent presentation of the conditioned odor also evokes an enhanced focal uptake of 2‐deoxyglucose (2‐DG) in the glomerular layer of the olfactory bulb, and the glomerular‐layer width of such foci increases in conditioned pups. In the present study, we determined whether an increase in the glomerular‐layer cell population contributes to this structural and functional change. We therefore counted and measured glomerular‐layer cells in Nissl‐stained sections from focal regions of radiolabeled 2‐DG uptake. While cell size did not differ between groups, conditioned pups had a 19% increase in the number of glomerular‐layer cells associated with the 2‐DG foci compared to controls. The increase in cell number may contribute to the enhanced 2‐DG uptake in glomerular‐layer foci.
Conditioning nerve crush accelerates cytoskeletal protein transport in sprouts that form after a subsequent crush
Authors: McQuarrie Irvine G. , Jacob Jane M. 
Published: January 2005

AbstractTo examine the relationship between axonal outgrowth and the delivery of cytoskeletal proteins to the growing axon tip, outgrowth was accelerated by using a conditioning nerve crush. Because slow component b (SCb) of axonal transport is the most rapid vehicle for carrying cytoskeletal proteins to the axon tip, the rate of SCb was measured in conditioned vs. sham‐conditioned sprouts. In young Sprague‐Dawley rats, the conditioning crush was made to sciatic nerve branches at the knee; 14 days later, the test crush was made where the L4 and L5 spinal nerves join to form the sciatic nerve in the flank. Newly synthesized proteins were labeled in motor neurons by injecting 35S‐methionine into the lumbar spinal cord 7 days before the test crush. The wave of pulse‐labeled SCb proteins reached the crush by the time it was made and subsequently entered sprouts. The nerve was removed and sectioned for SDS‐PAGE and fluorography 4–12 days after the crush. Tubulins, neurofilament proteins, and representative “cytomatrix” proteins (actin, calmodulin, and putative microtubule‐associated proteins) were removed from gels for liquid scintillation counting. Labeled SCb proteins entered sprouts without first accumulating in parent axon stumps, presumably because sprouts begin to grow within hours after axotomy. The peak of SCb moved 11% faster in conditioned than in sham‐conditioned sprouts: 3.0 vs. 2.7 mm/d (p <.05). To confirm that sprouts elongate more rapidly when a test crush is preceded by a conditioning crush, outgrowth distances were measured in a separate group of rats by labeling fast axonal transport with 3H‐proline 24 hours before nerve retrieval. The rate of outgrowth was 17% faster in conditioned than in sham‐conditioned sprouts: 5.13 vs. 4.38 mm/d (p <.01). The increase in outgrowth rate correlated with the increase in SCb rate, suggesting that outgrowth is a function of cytoskeletal protein transport.
Detection and characterization of a sensory microganglion associated with the spinal accessory nerve: A scanning laser confocal microscopic study of the neurons and their processes
Authors: Wetmore Cynthia , Elde Robert 
Published: January 2005

AbstractThe spinal accessory nerve has been generally thought to be a cranial nerve with purely motor function, innervating the trapezius and sternocleidomastoid muscles. The present study identified clusters of sensory neurons consistently associated with this cranial nerve in adult rats. Either a single microganglion or several dispersed microganglia were found that adhered to the spinal root of the nerve, to small vessels, or were free within the subarachnoid space. The neurons of the ganglion had axons that joined the spinal root of the nerve proximal to its exit from the skull. Additional branches appeared to have an intracranial distribution within the arachnoid of the brainstem and along its vessels.Several findings suggest that the function of the ganglion is sensory and not autonomic. First, the architectural features of neurons within the ganglion (including their size, pseudounipolar morphology, and the lack of synaptic contacts) are similar to those of neurons in other sensory ganglia. Second, substance P and calcitonin gene‐related peptide coexist within neurons of the microganglion, whereas markers for the major transmitters found in autonomic ganglia in rats are absent. Third, the expression of peptides in neurons of the ganglion was sensitive to neonatal capsaicin treatment. Finally, neurons within the ganglion were filled with a retrogradely transported dye after injection of the dye into the cervical spinal cord. Although the function of the ganglion is not known, its features are consistent with a role in nociception from the muscles of the spinal accessory complex, and it may be involved in headaches that have an occipital distribution.
Ultrastructure and aspects of functional organization of pyramidal and nonpyramidal entorhinal projection neurons contributing to the perforant path
Authors: Germroth Peter , Schwerdtfeger Walter K. , Buhl Eberhard H. 
Published: January 2005

AbstractIdentified entorhino‐hippocampal projection neurons were investigated for their ultrastructure. Spinous projection neurons (pyramidal and spiny stellate cells) display common features such as symmetric axosomatic terminals on their somata, asymmetric synapses on the spines, and both types of synapses on the dendritic shafts. Their axons descend towards the white matter, branching occasionally via collaterals which establish contact with local spines and rarely on dendritic shafts and somata. The sparsely spinous projection neurons (multipolar and horizontal‐bipolar) typically show deep nuclear infolds and symmetric and asymmetric synapses on their somata and dendritic shafts. Axons also collateralize in the soma vicinity and form local synapses. It is concluded that the entorhino‐hippocampal projection neurons (both spiny and sparsely spinous) act locally and distally thus performing simultaneously as local‐circuit and as projection neurons. In accordance with other morphological and electrophysiological reports it appears likely that the generation, modulation, and suppression of entorhinal excitation waves is mediated by these neurons through direct excitation, feed‐forward and feed‐back inhibition, and disinhibition.
Targets of horizontal connections in macaque primary visual cortex
Authors: McGuire Barbara A. , Gilbert Charles D. , Rivlin Patricia K. , Wiesel Torsten N. 
Published: January 2005

AbstractPyramidal neurons within the cerebral cortex are known to make long‐range horizontal connections via an extensive axonal collateral system. The synaptic characteristics and specificities of these connections were studied at the ultrastructural level. Two superficial layer pyramidal cells in the primate striate cortex were labeled by intracellular injections with horseradish peroxidase (HRP) and their axon terminals were subsequently examined with the technique of electron microscopic (EM) serial reconstruction. At the light microscopic level both cells showed the characteristic pattern of widespread, clustered axon collaterals. We examined collateral clusters located near the dendritic field (proximal) and approximately 0.5 mm away (distal). The synapses were of the asymmetric/round vesicle variety (type I), and were therefore presumably excitatory. Three‐quarters of the postsynaptic targets were the dendritic spines of other pyramidal cells. A few of the axodendritic synapses were with the shafts of pyramidal cells, bringing the proportion of pyramidal cell targets to 80%. The remaining labeled endings were made with the dendritic shafts of smooth stellate cells, which are presumed to be (GABA)ergic inhibitory cells. On the basis of serial reconstruction of a few of these cells and their dendrites, a likely candidate for one target inhibitory cell is the small‐medium basket cell. Taken together, this pattern of outputs suggests a mixture of postsynaptic effects mediated by monosynaptic excitation followed by combined disynaptic inhibition and excitation. As a consequence the horizontal connections may well be the substrate for the variety of influences observed between the receptive field center and its surround.
Evidence for enkephalin‐ and endorphin‐immunoreactive cells in the anterior pituitary of the axolotl Ambystoma mexicanum
Authors: Leon‐Olea Martha , Sanchez‐Alvarez Marcela , Pĩa Ana Luisa , Bayon Alejandro 
Published: January 2005

AbstractAn immunohistochemical study of opioid peptides in the hypophysis of the axolotl, Ambystoma mexicanum, was carried out with antisera against leu‐enkephalin, beta‐endorphin, met‐enkephalin, and dynorphin A (1–8). We found leu‐enkephalin immunoreactivity in some fibers of the neural lobe and the median eminence. In contrast to previous reports on mammals and other vertebrates, we found leu‐enkephalin immunoreactivity in many cells scattered throughout the anterior lobe. As in other vertebrates, the beta‐endorphin immunoreactivity was present in all the cells of the intermediate lobe and in a few cells of the anterior lobe. Met‐enkephalin and dynorphin A (1–8) immunoreactivities were only present in the neural lobe and the median eminence. The presence of leu‐enkephalin and beta‐endorphin in the anterior lobe suggests that these peptides could be acting as hormones released from the hypophysis of the unmetamorphosed amphibian.
GABA‐like immunoreactivity in the tuberomammillary nucleus: An electron microscopic study in the rat
Authors: Ericson Hans , Köhler Christer , Blomqvist Anders 
Published: January 2005

AbstractThe organization of GABAergic elements in the histaminergic tuberomammillary nucleus has been examined by using antibodies against γ‐aminobutyric acid (GABA) and light and electron microscopy.Most neuronal perikarya of the ventral subgroup of the tuberomammillary nucleus were GABA immunoreactive (GABA‐i). The morphology of the GABA‐i perikarya was similar to the morphology of histaminergic perikarya described by Hayashi et al. ('84: J. Comp. Neurol. 229:233–241) and Wouterlood et al. ('86: J. Comp. Neurol. 252:227–243).The GABA‐i perikarya were contacted by relatively few terminals. The mean bouton covering ratio of GABA‐i perikarya was 6.1%, whereas the mean bouton covering ratio for GABA‐i dendrites in the tuberomammillary nucleus was 31%. Some of the presynaptic terminals were GABA‐i. In addition, GABA‐i perikarya and dendrites formed close contacts that never presented synaptic specializations. These results suggest that neurons of the histaminergic tuberomammillary nucleus contain the neurotransmitter GABA. Furthermore, GABA may act as a modulator of cellular processes within the tuberomammillary nucleus.