bluuebunny/crossref_metadata_2025_split huggingface dataset:
Afferents to the abducens nucleus in the monkey and cat
Authors: Langer T. , Kaneko C. R. S. , Scudder C. A. , Fuchs A. F. 
Published: January 2005

AbstractThe abducens nucleus is a central coordinating element in the generation of conjugate horizontal eye movements. As such, it should receive and combine information relevant to visual fixation, saccadic eye movements, and smooth eye movements evoked by vestibular and visual stimuli. To reveal possible sources of these signals, we retrogradely labeled the afferents to the abducens nucleus by electrophoretically injecting horseradish peroxidase into an abducens nucleus in four monkeys and two cats. The histologic material was processed by the tetramethyl benzidine (TMB) method of Mesulam.

In both species the largest source of afferents to the abducens nucleus was bilateral projections from the ventrolateral vestibular nucleus and the rostral pole of the medial vestibular nucleus. Scattered neurons were also labeled in the middle and caudal levels of the medial vestibular nucleus.
Large numbers of neurons were labeled in the ventral margin of the nucleus prepositus hypoglossi in the cat and in the common margin of the nucleus prepositus and the medial vestibular nucleus in the monkey, a region we call the marginal zone.
Substantial numbers of retrogradely labeled neurons were found in the dorsomedial pontine reticular formation both caudal and rostral to the abducens nuclei.
In the monkey, large numbers of labeled neurons were present in the contralateral medial rectus subdivision of the oculomotor complex, while smaller numbers occurred in the ipsilateral medial rectus subdivision and elsewhere in the oculomotor complex. In the cat, large numbers of retrogradely labeled cells were present in a small periaqueductal gray nucleus immediately dorsal to the caudal pole of the oculomotor complex, and a few labeled neurons were also dispersed through the caudal part of the oculomotor complex.
Occasional labeled neurons were present in the contralateral superior colliculus in both species. The size and distribution of the labeled neurons within the intermediate gray differed dramatically in the two species. In the cat, the retrogradely labeled neurons were very large and occurred predominantly in the central region of the colliculus, while in the monkey, they were small to intermediate in size and were distributed more uniformly within the middle gray.
Among the afferent populations present in the monkey, but not in the cat, was a group of scattered neurons in the ipsilateral rostral interstitial nucleus of the medial longitudinal fasciculus and a denser, bilateral population in the interstitial nucleus of Cajal. A few labeled neurons were also present in the nucleus reticularis tegmenti pontis in the monkey, but not in the cat. Small numbers of retrogradely labeled neurons were present in the monkey's y‐group and superior vestibular nucleus.
It appears that while the monkey and the cat have similar sets of abducens afferents, there are definite differences in the details of the innervation of the abducens nucleus in the two species.
Central connections of the lingual tonsillar branch of the glossopharyngeal nerve and the superior laryngeal nerve in lamb
Authors: Sweazey Robert D. , Bradley Robert M. 
Published: January 2005

AbstractAfferent and efferent central connections of the lingual‐tonsillar branch of the glossopharyngeal nerve (LT‐IX) and the superior laryngeal nerve (SLN) in the lamb were traced with horseradish peroxidase (HRP) histochemistry. After entering the brainstem, most LT‐IX and SLN afferent fibers turned caudally in the solitary tract (ST). Some afferent fibers of LT‐IX terminated in the medial nucleus of the solitary tract slightly caudal to their level of entry. The remaining fibers projected to the dorsolateral, ventrolateral, and interstitial areas of the nucleus of the solitary tract (NST) at the level of the area postrema. Superior laryngeal nerve afferent fibers terminated extensively in the medial and ventral NST at levels near the rostral pole of the area postrema. Further caudal, near the level of obex, SLN afferent terminations were concentrated in the region ventrolateral to the ST and in the interstitial NST. The caudal extent of LT‐IX and the rostral extent of SLN terminals projected to similar levels of the NST, but only a relatively small proportion of the total projections overlapped. Lingualtonsillar and SLN fibers also coursed rostrally to terminate in the caudal pons within and medial to the dorsomedial principal sensory trigeminal nucleus. Other labeled afferent fibers traveled caudally in the dorsal spinal trigeminal tract to terminate in the dorsal two‐thirds of the spinal trigeminal nucleus at the level of obex. Large numbers of labeled cells with fibers in the LT‐IX or SLN were located in the ipsilateral rostral nucleus ambiguus and surrounding reticular formation. Fewer labeled cells were observed in the inferior salivatory nucleus following HRP application to either the LTIX or SLN. The LT‐IX and SLN projections to areas of the NST associated with upper airway functions, like swallowing and respiration, suggest an important role for these two nerves in the initiation and control of airway reflexes.
The innervation of tandem muscle spindles in the cat neck
Authors: Richmond F. J. R. , Bakker G. J. , Bakker D. A. , Stacey M. J. 
Published: January 2005

AbstractPatterns of innervation were examined in tandem muscle spindles teased from silver‐stained muscles of the cat neck. Each tandem spindle was composed of two or more encapsulated receptors linked in series by a shared bag2 fiber. In most tandem spindles, two different types of encapsulation were identified according to differences in their intrafusal fiber content. One type, the b1b2c unit, contained typical bag1, bag2, and chain fibers and was structurally similar to single spindles described in other cat muscles. Each b1b2c unit contained a single primary sensory ending and 1‐6 secondary endings. Fusimotor innervation was supplied by many axons. Some fusimotor axons ended in trail ramifications on bag2 and chain fibers, others ended in plates on the bag1 or long chain fiber. The other type of tandem encapsulation, the b2c unit, had only bag2 and chain fibers in its intrafusal fiber bundle. The b2c unit was usually supplied by only one sensory axon that ended on the nucleated part of the intrafusal fiber bundle. This single ending had a more variable terminal morphology than the primary ending in b1b2c units. A few b2c units (3/49) were also supplied by a secondary ending. The fusimotor innervation of the b2c unit was relatively simple. A single pole of the b2c unit was usually supplied by only one to three axons, all ending in trail ramifications. No plate endings were found in b2c units. These morphological specializations suggest that b1b2c and b2c units in tandem spindles differ in both their transductive and fusimotor mechanisms. Thus, the tandem spindle is a specialized structure that may provide additional proprioceptive information beyond that available from single muscle spindles.
The overlap of spinothalamic and dorsal column nuclei projections in the ventrobasal complex of the rat thalamus: A double anterograde labeling study using light microscopy analysis
Authors: Ma Wu , Peschanski Marc , Besson Jean‐Marie 
Published: January 2005

AbstractProjections from the spinal cord and the dorsal column nuclei (DCN) to the ventrobasal complex of the thalamus (VB) were studied in the rat by using double anterograde labeling strategy. This strategy was based on the injection of 3H‐leucine into the DCN and of wheat germ agglutinin conjugated to horseradish perexidase (WGA‐HRP) into the spinal cord and their subsequent transport. Adjacent 30‐μm‐thick sections were then processed differentially for autoradiography or for HRP by using tetramethyl benzidine (TMB) as a chromogen.Similar areas of the ventrobasal complex were labeled, in adjacent sections, after a large injection of 3H‐leucine into the DCN and when wheat germ agglutinin‐HRP had been injected in any part of the spinal cord. If, however, a small injection of the radioactive tracer was centered in the gracile nucleus and compared with an injection of WGA‐HRP placed in the lumbar enlargement of the cord, the rostral and dorsal portions of the lateral VB were labeled from both sources. On the other hand, if tritiated leucine was injected into the cuneate nucleus, and WGA‐HRP placed in the cervical enlargement, then the caudal and ventral portions of the lateral VB demonstrated overlap of both labels.The present results show that, in the rat, areas of termination of both the spinothalamic tract and the lemniscal pathway originating from the DCN overlap in the lateral VB. This overlap is somatotopically organized, thus indicating that the same area of the VB receives somatic inputs from one particular part of the body through both pathways. These results are discussed in comparison to those of comparable studies performed in the cat and in the monkey and with reference to the electrophysiological data that have demonstrated that, in the rat VB, neurons responding to noxious stimulation are intermingled with neurons exclusively responding to non‐noxious stimulation.
Degeneration and regeneration of peripheral nerve in the rat trigeminal system. I. Identification and characterization of the multiple afferent innervation of the mystacial vibrissae
Authors: Renehan William E. , Munger Bryce L. 
Published: January 2005

AbstractLight and electron microscopic techniques were utilized to examine the sensory innervation of the rat mystacial vibrissa. Each vibrissa is innervated by a large nerve bundle that enters the hair below the level of the Ringwulst and a smaller bundle (conus nerve) that pierces the capsule at the top of the hair. The main nerve bundle innervates four types of sensory receptors: (1) free nerve endings (FNEs), (2) lanceolate receptors in the connective tissue below the Ringwulst, (3) Merkel cell‐neurite complexes in the outer root sheath, and (4) lanceolate receptors in the intermediary zone. The smaller nerve bundle innervates the area of the sinus hair referred to as the conical body and supplies (1) a Ruffini corpuscle, (2) FNEs, and (3) lanceolate receptors in the inner conical body. The Ruffini complex of the inner conical body and the FNEs of the dense connective tissue below the Ringwulst have not been identified in previous morphological studies of the rat sinus hair. The Ruffini corpuscle, characterized by the compartmentalization of collagen bundles by Schwann cells and fibroblasts (septal cells), encircles the hair shaft in a manner analogous to the Ruffini complexes of nonsinus hairs. Identification of this receptor in the rat vibrissa provides an anatomic explanation for physiological recordings of mystacial primary afferents with slowly adapting type II properties in the rat.
The absence of significant postnatal motoneuron death in the brachial and lumbar spinal cord of the rat
Authors: Oppenheim Ronald W. 
Published: January 2005

AbstractMotoneuron numbers in the brachial and lumbar lateral motor column (LMC) of the rat were examined quantitatively on embryonic day (E) 15 and postnatal days (P) 1‐5. There was a significant (40‐45%) loss of motoneurons in both regions between E15 and P1. No further loss was observed between P1 and P5. The decline of motoneurons between E15 and P1 is very likely due to cell death since there were considerable numbers of dying motoneurons present on E15. By contrast, few dying motoneurons were observed on P1‐P5. Possible reasons for discrepancies between the present results and previous investigations are discussed. It is concluded that there is not a significant loss of either brachial or lumbar motoneurons in the postnatal rat and thus that postnatal rearrangements of muscle innervation are most likely the result of axon elimination, not cell death.
Postnatal changes in arborization patterns of murine retinocollicular axons
Authors: Sachs George M. , Jacobson Margaretha , Caviness Verne S. 
Published: January 2005

AbstractThe growth and arborization of murine retinocollicular axons have been studied by means of HRP axon filling during postnatal development. Transformations in arborization patterns have been correlated with changes in synaptic density in the superficial collicular neuropil and with the formation of synapses by HRP‐filled axons. At all postnatal ages axons of the optic projection are fasciculated and most follow a rostrocaudally aligned path. On the day of birth the axons course through both stratum griseum superficiale (SGS) and stratum opticum (SO); during the following 4 days the axon trunks disappear from SGS and are subsequently found only in SO. From postnatal day (P) 0 to P3, the majority continue far caudally in the colliculus, giving rise to small ascending collaterals at multiple points along their course. Ultimately, usually by P3, one or two collaterals begin to branch profusely and by P5 the majority of axons give rise to a focal terminal ascending arborization.The general configuration of most arborizations at P3 approximates that of the mature axon. However, the richness of terminal branching increases from P3 through the first 2 postnatal weeks. Synaptic density is relatively low in the first postnatal week, and no synapses involving HRPfilled optic axons were identified in this interval. Subsequently, after elaboration of definitive arbors has begun, synaptogenesis in the surrounding neuropil accelerates. Synaptic density in the upper SGS approximates adult values early in the third postnatal week. By this time synaptic junctions involving the terminal arborizations of optic axons are abundant.
Amino acid labeling patterns in the efferent innervation of the cochlea: An electron microscopic autoradiographic study
Authors: Schwartz I. R. , Ryan A. F. 
Published: January 2005

AbstractLight microscopic autoradiography and electron microscopic autoradiography were used to study the distribution of label in the cochlear efferents following in vivo incubation with tritiated amino acids. Two basic patterns of labeling were observed. These patterns correspond closely to the lateral and medial superior olivary complex (SOC) olivocochlear systems identified by Warr and Guinan ('79, Brain Res. 173:152‐155). Our electron microscopic observations suggest that, at least in the gerbil, the complete separation of outer hair cell (OHC) versus inner hair cell (IHC) efferent innervation proposed by these investigators based upon light microscopic data does not occur. Rather, our data suggest that while the lateral SOC system supplies endings only to the region under the IHC, the medial SOC system may supply endings beneath both the IHCs and OHCs.
Organization of the callosal connections of visual areas v1 and v2 in the macaque monkey
Authors: Kennedy Henry , Dehay Colette , Bullier Jean 
Published: January 2005

AbstractThe interhemispheric efferent and afferent connections of the V1/V2 border have been examined in the adult macaque monkey with the tracers horseradish peroxidase and horseradish peroxidase conjugated to wheat germ agglutinin. The V1/V2 border was found to have reciprocal connections with the contralateral visual area V1, as well as with three other cortical sites situated in the posterior bank of the lunate sulcus, the anterior bank of the lunate sulcus, and the posterior bank of the superior temporal sulcus.Within V1, callosal projecting cells were found mainly in layer 4B with a few cells in layer 3. Anterograde labeled terminals were restricted to layers 2, 3, 4B, and 5. In extrastriate cortex, retrograde labeled cells were in layers 2 and 3 and only very rarely in infragranular layers. In the posterior bank of the lunate sulcus, labeled terminals were scattered throughout all cortical layers except layers 1 and 4. In the anterior bank of the lunate sulcus and in the superior temporal sulcus, anterograde labeled terminals were largely focused in layer 4.Callosal connections in all contralateral regions were organized in a columnar fashion. Columnar organization of callosal connections was more apparent for anterograde labeled terminals than for retrograde labeled neurons. In the posterior bank of the lunate sulcus, columns of callosal connections were superimposed on regions of high cytochrome activity.The tangential extent of callosal connections in V1 and V2 was found to be influenced by eccentricity in the visual field. Callosal connections were denser in the region of V1 subserving foveal visual field than in cortex representing the periphery. In V1 subserving the fovea, callosal connections extended up to 2 mm from the V1/V2 border and only up to 1 mm in more peripheral located cortex. In area V2 subserving the fovea, cortical connections extended up to 8 mm from the V1/V2 border and only up to 3 mm in peripheral cortex.
Origin and central projections of rat dorsal penile nerve: Possible direct projection to autonomic and somatic neurons by primary afferents of nonmuscle origin
Authors: Núñez Ramon , Gross Gayle H. , Sachs Benjamin D. 
Published: January 2005

AbstractCell number, size, and somatotopic arrangement within the spinal ganglia of the cells of origin of the rat dorsal penile nerve (DPN), and their spinal cord projections, were studied by loading the proximal stump of the severed DPN with horseradish peroxidase (HRP). The DPN sensory cells were located entirely in the sixth lumbar (L6) dorsal root ganglia (DRG), in which a mean of 468 ± 78 cells per side were observed, measuring 26.7 ± 0.8 μm in their longest axis (range 10–65 μm) and distributed apparently randomly within the ganglia.Within the spinal cord, no retrograde label was found, i.e., no motoneurons were labeled, indicating that in the rat the DPN is formed exclusively of sensory nerve fibers.Although labeled fibers entered the cord only through L6, transganglionically transported HRP was evident in all spinal segments examined, i.e., T13‐S2. Labeled fibers projected along the inner edge of the dorsal horn (medial pathway) throughout their extensive craniosacral distribution. However, laminar distribution varied with spinal segment. In the dorsal horn, terminals or preterminal axons were found in the dorsal horn marginal zone (lamina I), the substantia gelatinosa (lamina II), the nucleus proprius (laminae III and IV‐the most consistent projection), Clarke's column (lamina VI), and the dorsal gray commissure. In the ventral horn, terminals were found in lamina VII and lamina IX.Label apposed to cell somas and dentrites in lamina VII may represent direct primary afferent projections onto sympathetic autonomic neurons. In lamina IX, labeled terminals delineated the somas and dendrites of cells that appeared to be motoneurons. This is the first description of an apparently monosynaptic contact onto motoneurons by a primary afferent of nonmuscle origin.
Afferent projections to the interpeduncular nucleus in the rat, as studied by retrograde and anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase
Authors: Shibata Hideshi , Suzuki Takashi , Matsushita Matsuo 
Published: January 2005

AbstractWe examined the afferent projections to the subnuclei of the interpeduncular nucleus (IPN) in the rat by means of retrograde and anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). We observed locations of retrogradely labeled cells following injections of WGA‐HRP into the IPN, and distributions of anterogradely labeled fibers and terminals within the IPN following injections into the areas that contain cells of origin of afferents.Results of the retrograde and anterograde experiments have clarified the detailed organization of the IPN afferents. A part of the nucleus incertus, located dorsomedial to the dorsal tegmental nucleus, projects to the contralateral half of the rostral subnucleus of the IPN; the pars caudalis of the dorsal tegmental nucleus projects sparsely to the rostral lateral, dorsal lateral, lateral, caudal, and apical subnuclei predominantly contralaterally; the laterodorsal tegmental nucleus, to most of the subnuclei predominantly contralaterally; the ventromedial central gray rostral to the dorsal tegmental nucleus and lateral to the dorsal raphe nucleus projects to the rostral lateral and dorsal lateral subnuclei predominantly contralaterally; the median raphe nucleus, substantially to all subnuclei; the medial habenular nucleus, in a topographic manner, to the rostral, central, and intermediate subnuclei, to the rostral lateral and lateral subnuclei predominantly ipsilaterally, and to the dorsal lateral subnucleus predominantly contralaterally; the supramammillary nucleus and areas around the origin of the mammillothalamic tract and near the third ventricle project sparsely to the ventral part of the rostral subnucleus and to the central, lateral, caudal and apical subnuclei; the nucleus of the diagonal band, sparsely to the rostral, central, dorsal lateral, caudal, and apical subnuclei.These differential projections of the afferents to the subnuclei of the IPN may reflect its complex functions within the limbic midbrain circuit.
Distribution of tyrosine hydroxylase and neuropeptide Y–like immunoreactive neurons in rabbit medulla oblongata, with attention to colocalization studies, presumptive adrenaline‐synthesizing perikarya, and vagal preganglionic cells
Authors: Blessing W. W. , Howe P. R. C. , Joh T. H. , Oliver J. R. , Willoughby J. O. 
Published: January 2005

AbstractWe studied the distribution, within the rabbit medulla oblongata, of neuronal cell bodies containing either tyrosine hydroxylase or neuropeptide Y‐like immunoreactivity. Both avidin‐biotin and immunofluorescence procedures were used. Because the two primary antibodies were raised in different species it was possible to perform simultaneous colocalization studies with the immunofluorescence procedure. Tyrosine hydroxylase‐containing neurons in the rostral medulla were demonstrated to contain a catecholamine by the colchicine‐enhanced FAGLU (formaldehyde‐glutaraldehyde) fluorescence histochemical procedure. These neurons are presumably adrenergic, corresponding to the C1 and C2 groups described in the rat. No C3 group was found in the rabbit. The distribution of tyrosine hydroxylase–containing neurons in the caudal medulla was in accordance with previous descriptions of the A1 and A2 groups based on the unenhanced FAGLU procedure.Neuropeptide Y–like immunoreactivity was observed in cell groups corresponding to those already described in the rat, but additional groups were discovered in the rabbit. Some neurons containing neuropeptide Y–like immunoreactivity were observed in nucleus raphe pallidus and these also contained serotonin (5‐HT). In the nearby nucleus reticularis gigantocellularis there were occasional neurons that contained neuropeptide Y–like immunoreactivity without any colocalized 5‐HT. Neuropeptide Y–like immunoreactivity was also observed in the dorsal motor nucleus of the vagus, rostral to the obex, and these neurons were demonstrated to be true vagal preganglionic cells by colocalization of neuropeptide Y–like immunoreactivity and Fast Blueretrogradely transported from the cervical vagus.We found that neuropeptide Y–like immunoreactivity was colocalized in approximately 75% of the tyrosine hydroxylase‐containing neurons in the rostral medulla (C1 and C2 cells). A smaller proportion of the A1 cells also contained this peptide but it was absent from both the most caudal A1 cells and from the A2 cells.Some tyrosine hydroxylase–containing neurons occur in direct apposition to vagal preganglionic cells in both the dorsal motor nucleus of the vagus and the nucleus ambiguus. However, colocalization studies revealed that none of these neurons contained Fast Blue when this dye was retrogradely transported from the cervical vagus. Medullary catecholamine‐synthesizing neurons apparently do not contribute axons to the vagus nerve. This finding is consistent with our own studies in the rat but is in contrast to studies in this species published by other workers.