bluuebunny/crossref_metadata_2025_split huggingface dataset:
Migration of schwann cells and axons into developing chick forelimb muscles following removal of either the neural tube or the neural crest
Authors: Noakes Peter G. , Bennett Max R. , Stratford Jacqueline 
Published: January 2005

AbstractA study has been made of the effects of neural crest and neural tube removal at the brachial level on the migration of Schwann cells and axons into the flexor digitorum profundus (fdp) and flexor carpi ulnaris (fcu) muscles of the avian forelimb. The identification of Schwann cells was based on the assumption that antibody HNK‐1 uniquely labels these cells at the growing end of limb nerves. Myotubes and nerves were identified by using antibodies to myosin and to neurofilament protein, respectively. The removal of neural crest cells at stage 13 gave a complete Schwann cell‐free embryo at the brachial level. Motor axons only grew to the base of the forelimb, forming a rudimentary plexus by stage 27, and failed to penetrate the limb. Removal of the neural tube at stage 13 did not prevent sensory axons from forming a plexus at the base of the limb; these axons subsequently developed into the brachialis longus inferior (bli n) and superior (bls n) nerves. By stage 27 the bli n had branched into the interosseus nerve (in n) and the medial‐ulnar nerve (m‐u n) trunks. However, unlike the result in control embryos, no nerves were detected amongst the developing fdp and fcu muscles, thus indicating that sensory axons do not grow into the muscles in the absence of motor axons. In contrast, Schwann cells were observed amongst the myotubes at the level of the in n and m‐u nerve trunks. The present observations show that motor axons do not enter the limb bud and innervate limb muscles in the absence of Schwann cells. Furthermore, in the absence of motor axons (neural‐tube‐removed embryos) sensory axons still enter the limb (behind migrating Schwann cells) but fail to innervate developing muscles even though Schwann cells are present among the developing myotubes.
Projections of submucosal neurons to the myenteric plexus of the guinea pig intestine: In vitro tracing of microcircuits by retrograde and anterograde transport
Authors: Kirchgessner A. L. , Gershon M. D. 
Published: January 2005

AbstractThe enteric nervous system (ENS) can mediate reflex activity without input from the brain or spinal cord. The ENS thus contains intrinsic primary afferent neurons that link mucosal sensory receptors with motor neurons in the myenteric plexus. The intrinsic primary afferent neurons of the gut have not yet been identified. Although the submucosal plexus is known to innervate the mucosa, where enteric sensory receptors are located, no submucosal to myenteric projections have previously been found. In order to detemine whether such projections exist, the submucosal plexus was examined following the microinjection of a retrograde tracer (Fluoro‐Gold or 4‐acetoamido, 4′‐isothiocyanostilbene‐2,2′‐disulphonic acid [SITS]) into single myenteric ganglia. In addition, the myenteric plexus was studied following the iontophoretic injection of an anterograde tracer (Phaseolus vulgaris leucoagglutinin; [PHA‐L]) into single submucosal ganglia. Ganglia were visualized by use of differential interference contrast optics and were injected from the beveled tip of a glass micropipette; 2.5–3.0 hours were allotted for retrograde and 20–24 hours (under culture conditions) for anterograde transport. In the myenteric plexus, a small number of the neurons of each injected ganglion were fluorescent and additional neurons in distant myenteric ganglia (predominantly orad) were also retrogradely labeled. About five to six submucosal neurons deep to but not directly underneath the injected myenteric ganglion were labeled by Fluoro‐Gold or SITS and only rarely was there more than one labeled neuron in a submucosal ganglion. When control injections of Fluoro‐Gold were placed into the muscle instead of a ganglion, some myenteric neurons near the injection site became labeled indicating an innervation of the circular muscle by myenteric neurons; however, there was no labeling of neurons in the submucosal plexus. Similarly, if connections between the myenteric and submucosal plexuses were severed before injecting Fluoro‐Gold, no submucosal neurons were labeled. Following injection of PHA‐L into a single submucosal ganglion, small‐diameter axons were labeled in ∼︁2 myenteric ganglia as well as in several distant submucosal ganglia (mainly anal and circumferential to the injection site). Additional labeled fibers traveled with blood vessels or surrounded mucosal crypts. It is concluded that submucosal neurons project to the myenteric plexus as well as to the mucosa and to one another. These observations are consistent with the hypothesis that at least some intrinsic enteric primary afferent neurons reside in the submucosal plexus.
Cholinergic innervation of canine thalamostriatal projection neurons: An ultrastructural study combining choline acetyltransferase immunocytochemistry and WGA‐HRP retrograde labeling
Authors: Isaacson Lori G. , Tanaka Duke 
Published: January 2005

AbstractCholine acetyltransferase (ChAT) immunocytochemistry and lectin‐conjugated horseradish peroxidase (WGA‐HRP) histochemistry were combined at the electron microscopic level to examine the morphology of cholinergic terminals in the canine centrum medianum—parafascicular complex (CM‐Pf) and to localize cholinergic terminals making synaptic contact with retrogradely labeled CM‐Pf thalamostriatal projection neurons. Following WGA‐HRP injections into the caudate nucleus, CM‐Pf neurons were heavily labeled with WGA‐HRP reaction product. Examination with the electron microscope revealed retrogradely labeled neurons characterized by a large nucleus with deep infoldings of the nuclear envelope. ChAT‐positive terminals were observed arising from small‐diameter nonmyelinated axonal profiles. These terminals varied in size from 0.5 to 1.4 μm in long diameter. The smaller terminals (0.5–0.7 μm) were seen most frequently and established symmetrical or slightly asymmetrical synaptic contacts with small dendritic profiles. The larger ChAT‐positive terminals (1.0–1.4 μm) were less frequently observed, contained several mitochondria and small clusters of pleomorphic vesicles, and contacted large dendritic shafts and cell somata. Some of the postsynaptic targets of both smaller and larger ChAT‐positive terminals were identified as belonging to retrogradely HRP‐labeled thalamostriatal neurons.These observations indicate that at least some thalamostriatal neurons within the CM‐Pf complex are innervated by cholinergic terminals which probably arise from ChAT‐positive cell bodies located within the pontomesencephalic tegmentum, particularly within the nucleus tegmenti pedunculopontinus and the laterodorsal tegmental nucleus. These findings provide evidence for direct influence by cholinergic brainstem nuclei over activities of thalamostriatal neurons.
Sequential development of connections between striate and extrastriate visual cortical areas in the rat
Authors: Coogan Thomas A. , Burkhalter Andreas 
Published: January 2005

AbstractIn these experiments we have asked whether the projection from the rat's primary visual cortex, area 17, to the extrastriate visual cortical area 18a is formed in a sequence and whether that sequence resembles the pattern of inside‐out cortical neurogenesis. For this purpose fluorescent retrograde tracers were injected into area 18a at different postnatal ages (P1, P5, adult). Animals survived until 3–4 weeks of age, after migration is complete and neurons have arrived at their final laminar location. In the ipsilateral cortex, P1 injections retrogradely labeled cells in layers 5 and 6 of area 17. Labeling after P5 injections extended into more superfical layers and included the bottom of layer 2/3 and layers 4–6. After P5, more labeled cells were found at the top of layer 2/3, producing the adult laminar pattern, where the projection originates predominantly from layer 2/3. A similar sequence of laminar labeling was observed in the transcallosal connection of area 18a. This sequence of labeling, deep layers before superficial, resembles the pattern in which cortical neurons are born and indicates that axons arrive at their cortical targets in the order the cells were generated.
Distribution of substance P and vasoactive intestinal polypeptide neurons in the chicken spinal cord, with notes on their postnatal development
Authors: Du Fu , Dubois Paul 
Published: January 2005

AbstractThe distribution of substance P (SP) and vasoactive intestinal polypeptide (VIP) was investigated by immunohistochemistry in the adult chicken spinal cord. By using colchicine treatment, populations of neurons containing either SP or VIP was observed in several regions of the spinal cord. SP neurons were found dorsal to the central canal (CC) and in lamina IV throughout the cord. However, at the thoracic level, numerous relatively larger SP perikarya were located ventral to the CC and aligned on either side of the midline. The distribution of SP fibers is very similar to that reported previously in mammals: they were mostly observed in laminae I and II, in Lissauer's tract, in the dorsolateral funiculus, and dorsal to the CC. In addition, two dense plexuses of SP fibers were noticed in lamina IV. VIP neurons were located mainly in lamina I, in the nucleus of the dorsolateral funiculus, and in the lateral portion of the neck of the dorsal horn throughout the spinal cord. At the thoracic level, many also were located lateral to the CC. Occasionally, single VIP neurons also were encountered dorsal to the CC, in laminae II–IV, and in the intermediate zone. VIP fibers were observed in similar numbers at all spinal levels, occurring mainly in laminae II (probably I) and III, dorsal to the CC, and in the intermediate zone. In addition, examination of the developing chick spinal cords showed similar results as in adult chickens.
Distribution of muscarinic receptor subtypes within architectonic subregions of the primate cerebral cortex
Authors: Mash Deborah C. , White W. Frost , Mesulam M.‐Marsel 
Published: January 2005

AbstractThe regional distributions of muscarinic receptor subtypes (M1 and M2) in the macaque brain were investigated by in vitro receptor autoradiography. Putative muscarinic receptor subtypes were distinguished by their differential affinities for pirenzepine and carbachol in competition with [3H]‐quinuclidinyl benzilate. Autoradiographic visualization of muscarinic receptor subtypes demonstrated marked regional and laminar variations that respected architectonic boundaries.The M1 receptor subtype was widely distributed throughout most cortical areas and was most intense over the superficial layers. Almost all limbic and paralimbic regions including the amygdala, hippocampus, orbitofrontal, temporopolar, parahippocampal, cingulate, and parolfactory areas displayed peak densities of the M1 receptor subtype. The M2 receptor subtype was selectively elevated in the primary sensory areas of all five sensory modalities, including the visual (area 17, V1), auditory (A1), and somatosensory (3b,S1) koniocortices, the anterior olfactory nucleus, and the gustatory area. The primary motor area also displayed a relative peak of M2 receptor subtype labeling.In the hippocampal formation, M1, M2, and nicotine receptors were distributed differentially, with each subdivision having a specific complement of cholinergic receptor subtype. The M1 receptor subtype was prevalent in the dentate gyrus, the CA4‐CA3 region, and the CA1 ammonic sector. The M2 receptor subtype was concentrated in the CA2 sector, the subiculum, the rhinal cortices, and the parasubiculum. Putative neural nicotinic receptors, tagged with L‐[3H]‐nicotine, were most concentrated within the presubiculum.
Direct projection of the corticospinal tract to the superficial laminae of the spinal cord in the rat
Authors: Casale Eugene J. , Light Alan R. , Rustioni Aldo 
Published: January 2005

AbstractThe anterograde transport of both wheat germ agglutinin conjugated to horseradish peroxidase and the kidney bean lectin Phaseolus vulgaris leucoagglutinin was utilized to investigate the projection of primary sensorimotor corticospinal tract axons to the superficial laminae of the spinal dorsal horn in the rat. Both methods yielded qualitatively similar patterns of connectivity. Corticospinal tract axons were found to terminate within all laminae on the side contralateral to the injection site. Labeling was most dense within laminae III and IV and medial portions of laminae I, II, and V in the cervical and lumbar enlargements. Labeling in the ventral horn, though present, was relatively less dense. P. vulgaris leucoagglutinin—labeled axons within laminae I and II exhibited boutons en passant and terminaux; many of these axons also terminated or were collaterals of axons that terminated in deeper dorsal horn laminae. Results are discussed with reference to the somatotopic organization of the spinal cord and to a possible role for the cortex in the modulation of nociception within the spinal cord.
Brainstem branches from olivocochlear axons in cats and rodents
Authors: Brown M. C. , Liberman M. C. , Benson T. E. , Ryugo D. K. 
Published: January 2005

AbstractHorseradish peroxidase was used to label axons of olivocochlear (OC) neurons by intracellular injections in cats and extracellular injections in rodents. These axons arise from cell bodies in the superior olivary complex and project to the cochlea. En route to the cochlea, the thick axons (> 0.7 μm diam.) of medial olivocochlear (MOC) neurons formed collaterals that terminated in the ventral cochlear nucleus, the interstitial nucleus of the vestibular nerve (in cats), and the inferior vestibular nucleus (in rodents). The thin axons (< 0.7 μm diam.), presumed to arise from lateral olivocochlear (LOC) neurons, did not branch near the CN. Within the CN, the MOC collaterals tended to ramify in and near regions with high densities of granule cells, regions also associated with the terminals of type II afferent axons (Brown et al.: J. Comp. Neurol. 278:581–590, '88). These results suggest that those fibers associated peripherally with outer hair cells (MOC efferents and type II afferents) are associated centrally with regions containing granule cells, whereas those fibers associated with inner hair cells peripherally (LOC efferents and type I afferents) are not.
Neuroanatomical studies of the nigrotectal projection in the cat
Authors: Harting J. K. , Huerta M. F. , Hashikawa T. , Weber J. T. , van Lieshout D. P. 
Published: January 2005

AbstractWe have used retrograde and anterograde transport methods to analyze then nigrotectal projection in the cat. This projection arises from both pars reticulata (SNr) and pars lateralis (SNl) and distributes to all cellular laminae of the superior colliculus. This extensive nigrotectal innervation is not a simple, single circuit. Rather it appears to consist of several parallel channels, with each taking origin from a particular zone of the substantia nigra and terminating within specific collicular laminae and/or sublaminae. For instance, only neurons within the SNl project to the stratum griseum superficiale; such neurons also project diffusely to all other tectal laminae. Cells in the most lateral portion of the SNr project to a horizontal, patchy tier in the interface region between the stratum opticum and the stratum griseum intermediale (SGI). Finally, more medially placed neurons within the SNr project to a horizontal patchy tier within the middle of the SGI and to a wedge‐shaped locus in the stratum griseum profundum.Our findings provide an anatomical substrate for electrophysiological data (Karabelas and Moschovakis: J. Comp. Neurol. 239:309–329, '85) showing a widespread distribution of nigrorecipient tectal neurons in the cat.
Auditory forebrain organization of an australian marsupial, the northern native cat (Dasyurus hallucatus)
Authors: Kudo Motoi , Aitkin Lindsay M. , Nelson John E. 
Published: January 2005

AbstractStructures and connections of auditory forebrain regions of the Northern native cat, a member of one of the most primitive families among Australian marsupials, have been examined anatomically by using anterograde and retrograde tracing techniques with wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) after defining the acoustically responsive neocortical area physiologically.The structure of the medial geniculate body (MG) was similar to that described in other species. The results obtained from a case with a WGA‐HRP injection into the MG showed that the MG strongly projects to the lateral amygdaloid nucleus (LAmy) and the putamen as well as the auditory neocortex (ACx). Results obtained from other cases with WGA‐HRP injections into the physiologically defined ACx show also that the ACx is connected not only with the ipsilateral MG and the contralateral ACx but also with the LAmy both bilaterally and reciprocally. The regions within the LAmy in which the MG‐LAmy projection fibers terminate largely overlap with those in which the ACx‐LAmy fibers terminate and the LAmy‐ACx pathway originates.The connectional relationships revealed in the present study‐that the LAmy receives auditory information from the MG and reciprocates auditory information with the ACx bilaterally‐strongly suggest that, in some primitive mammals with small neocortical areas, a specific portion of noncortical telencephalon functions as an auditory center and occupies a relatively large volume of space in the forebrain. It is possible that the auditory sector of noncortical telencephalon in some primitive mammals such as the American Didelphidae and the Australian Dasyuridae is homologous with part of the auditory sector of the dorsal ventricular ridge (DVR) in reptiles and birds and also may have functions shared with the auditory primary and association neocortex in advanced mammals such as the domestic cat and the monkey (Kudo et al., '86a).
GABA‐like immunoreactivity in the cat retina: Electron microscopy
Authors: Chun M. H. , Wässle H. 
Published: January 2005

AbstractThe synaptic organization of the cat retina was studied with antibodies against the GABA‐GA (glutaraldehyde)‐BSA (bovine serum albumin) complex. The postembedding technique combined with immunogold labelling ensured ultrastructural preservation and made identification of synapses possible. The most common putative GABA‐ergic synapses in the inner plexiform layer were amacrine‐to‐bipolar‐cell synapses followed by amacrine‐to‐ganglion‐cell and amacrine‐to‐amacrine‐cell synapses. GABA‐immunoreactive amacrine cells received most of their synaptic input from bipolar cells followed by other amacrine cells. Synapses between two labelled amacrine cells were common. Rod bipolar cells were the predominant input source and also the preferred output target of GABA‐labelled amacrine cells. OFF‐ and ON‐ganglion cells received putative GABA‐ergic synapses at their dendrites in laminas a and b, respectively, and also at their somata.In the outer plexiform layer, synapses of interplexiform cells onto bipolar cell dendrites expressed GABA‐like immunoreactivity. In both the cone pedicles and the rod spherules, GABA‐like immunoreactivity was observed in horizontal cell processes.
Zonal organization of climbing fiber projections to the uvula in the cat
Authors: Kanda Ken‐Ichi , Sato Yu , Ikarashi Katsumi , Kawasaki Tadashi 
Published: January 2005

AbstractClimbing fiber projections from the inferior olive to the uvula of the cerebellum were studied in the cat by using retrograde axonal transport of horseradish peroxidase. Following large and small injections into various parts of the uvula, the distribution of labeled cells in the inferior olive was investigated. The findings indicate six longitudinal zones extending throughout the dorsal and ventral uvula: the caudal part of the nucleus beta projects to a most medially located zone (caudal beta zone) with a width of about 0.4 mm; the rostral part of the nucleus beta projects to a zone located at about 0.6 mm from the midline (rostral beta zone); the caudal part of the medial accessory olive (MAO) projects to a zone (caudal MAO zone) located lateral to the rostral beta zone; the dorsomedial cell column projects to a zone (dorsomedial cell column zone) located in the intermediate part of the uvula at about 1.2 mm from the lateral edge of the uvula; the ventral lamella of the principal olive (PO) projects to a zone (ventral lamella of PO zone) about 0.7 mm from the lateral edge of the uvula; finally, the rostral part of the MAO projects to the most lateral zone (rostral MAO zone). These conclusions are in general agreement with those of earlier studies and also provide a more detailed zonal configuration of climbing fiber projections to the uvula.
Differential mossy fiber projections to the dorsal and ventral uvula in the cat
Authors: Sato Yu , Kanda Ken‐Ichi , Ikarashi Katsumi , Kawasaki Tadashi 
Published: January 2005

AbstractThe brainstem afferents to the uvula were studied by using retrograde axonal transport of horseradish peroxidase in the cat. Findings indicate differential afferent projections to the ventral and dorsal uvula. Major sources projecting to the ventral uvula include the caudal parts of the medial and inferior vestibular nuclei, the x‐ and f‐groups of the vestibular nuclei, the dorsal and central parts of the superior vestibular nucleus, the rostral dorsomedial part of the paramedian nucleus of the pontine nuclei, the caudal part of the prepositus hypoglossal nucleus, and the infratrigeminal nucleus. Labeled cells in the vestibular nuclei were 74.7% of the total number of labeled cells in cat 40. On the other hand, the major sources projecting to the dorsal uvula are the peduncular, paramedian, and lateral nuclei of the pontine nuclei at the rostral and intermediate levels. Labeled cells in the pontine nuclei comprised 82.1% of the total number of labeled cells in cat 1. Findings also indicate that the lateral part of the ventral uvula receives input mainly from the pontine nuclei, whereas the medial part of the ventral uvula receives input mainly from the vestibular nuclei. Mediolateral differences were not found for the dorsal uvula. These mossy fiber zones are mediolaterally wide, with a dorsoventral partition in the uvula, in contrast to the climbing fiber zones, which are narrow (about 0.4 mm) and extend longitudinally throughout the uvula.There are quantitative differences in afferent sources to the ventral uvula and flocculus, both of which belong to the vestibulocerebellum. The largest afferent sources for the ventral uvula are the vestibular nerve and nuclei, whereas the largest sources for the flocculus are the reticular formation and raphe nuclei. These quantitative differences may have an important role for differential functions between the ventral uvula and flocculus. It has been suggested that the ventral uvula controls the velocity storage integrator of the vestibuloocular and optokinetic reflexes, whereas the flocculus is responsible for rapid changes of eye velocity in these reflexes.