bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of cytochrome oxidase in the mammalian spinal cord and dorsal root ganglia, with quantitative analysis of ventral horn cells in monkeys
Authors: Wong‐Riley M. T. T. , Kageyama G. H.
Published: January 2005

The spinal cord and dorsal root ganglia of mice, rats, cats, squirrel monkeys, and macaque monkeys were examined at both the light and electron microscopic levels for cytochrome oxidase activity. A similar histochemical pattern prevailed in all of the species examined. While the spinal gray exhibited a heterogeneous but consistent distribution of the enzyme, the white matter was only lightly stained. Highly reactive neurons were either singly scattered or aggregated into discrete clusters. The dorsal nucleus of Clarke, the lateral cervical nucleus (cat), the intermediolateral cell columns of the thoracic and upper lumbar levels, and selected groups of ventral horn neurons formed moderate to darkly reactive cell clusters, whereas fusiform and multipolar cells of Waldeyer in the marginal layer, small fusiform neurons in the ventral gray, funicular cells in the white matter, and ventral horn neurons of varying sizes tended to stand out against the neuropil as singly reactive neurons. At the electron microscopic level, reactive neurons were characterized by a greater packing density of darkly reactive mitochondria, while lightly reactive ones had fewer mitochrondria, most of which showed very little reaction product. Reactive mitochondria were also found in the neuropil, mainly in dendritic profiles and some axon terminals. Glial cells, in general, were not very reactive.

Ventral horn neurons from three macaque monkeys were measured for somatic areas and optical densities of cytochrome oxidase reaction product. A total of 1,770 neurons from representative sections of the cervical, thoracic, lumbar, and sacral cords of these animals were analyzed. The results indicated that the distribution of cell sizes as well as optical densities at every level of the cord fell on a continuum. Analysis of the regression coefficients revealed that the slopes were negative for all levels, indicating that there was a general inverse relationship between cell size and optical densities. However, there were representations of dark, moderate, and lightly reactive neurons in all three size categories (large, medium; and small). Thus, the level of oxidative metabolism of ventral horn neurons cannot be correlated strictly with size, but it is likely to reflect their total synaptic and spontaneous activities.

Neurons of the dorsal root ganglia likewise exhibited heterogeneous distribution of cell sizes and levels of enzyme reactivity, while satellite cells, in general, were only lightly reactive. As in the case of the ventral horn, representatives of dark, moderate, and light levels of reactivity occurred in every size category of neurons. The finding was also confirmed at the electron microscopic level. The metabolic variations among ganglionic neurons again suggest a functional subclassification based mainly on their total energy demands, which should be related closely to their combined intrinsic and synaptic activities.
Sprouting of serotoninergic afferents into striatum after dopamine‐depleting lesions in infant rats: A retrograde transport and immunocytochemical study
Authors: Snyder Abigail M. , Zigmond Michael J. , Lund Raymond D.
Published: January 2005

Intraventricular injections of 6‐hydroxydopamine in 3‐day‐old rats resulted in the near‐total loss of tyrosine‐hydroxylase‐immunoreactive processes in the striatum when examined 2‐6 months later. This destruction of dopamine (DA) afferents was accompanied by an increase in the density of serotonin (5‐HT)‐immunoreactive fibers in the striatum. The hyperinnervation was most striking in the rostral striatum, an area containing few 5‐HT‐immunoreactive fibers in control rats. Retrograde tracing, with either horseradish peroxidase or rhodamine‐labelled microspheres, indicated a significant increase in the number of neurons projecting to the rostral striatum from the dorsal raphe nucleus of lesioned animals. The increase was largely confined to the rostral extent of the dorsal raphe, and overlapped the distribution of cells labelled after injections of HRP into caudal striatum of control and lesioned animals. In sections additionally processed for immunocytochemistry, 80–90% of retrogradely labelled raphe neurons in both groups of animals were found to be 5‐HT‐immunoreactive. None of changes encountered in infant‐lesioned rats were observed 2–4 weeks after 6‐HDA was given to adult animals. These findings demonstrate that removal of DA afferents during development leads to an enlargement of the serotoninergic projection from the raphe nucleus to the striatum.
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

The 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

Afferent 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

Patterns 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

Projections 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

Light 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

Motoneuron 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

The 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

Light 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

The 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

Cell 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

We 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

We 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.
VIP terminals, axons, and neurons: Distribution throughout the length of monkey and cat spinal cord
Authors: LaMotte C. C. , de Lanerolle N. C.
Published: January 2005

The distribution of vasoactive intestinal polypeptide (VIP) was mapped by peroxidase immunocytochemistry in the spinal cords of seven Macaca fascicularis monkeys and two cats. The animals were perfusion fixed with different chemicals. Those that were perfused with either a Zamboni fixative or 5% acrolein had significantly greater immunoreactivity outside the sacral cords; those fixed with 4% paraformaldehyde had little in nonsacral regions. VIP‐like immunoreactive (VIP) axons and terminals were found in the superficial dorsal horn, reticular nucleus of lamina V, intermediomedial nucleus, and lamina X at all levels from C2 to S4; a few axons and terminals were also seen in the ventral horn. Axons were found in Lissauer's tract at all levels, and axons appeared in the dorsolateral and ventrolateral white matter at midthoracic levels; in the lumbosacral cord the number and extent of axons in the lateral and ventral white matter increased progressively in a caudal direction. VIP neurons were identified in thoracic intermediate gray lateral to the central canal and in the intercalatus (IC) and intermediolateral (IML) nuclei. Electron microscopy of the VIP terminals in laminae I and II of the cervical cord revealed they contain small round vesicles and many large granular vesicles; some are glomerular terminals and most form asymmetrical synaptic contacts onto dendrites. These results indicate (1) VIP is much more widely distributed in the spinal cord than previously thought; (2) VIP may be associated with both visceral thoracic and lumbosacral afferents, and with other afferents in the cervical cord; (3) VIP neurons are present in the thoracic intermediate gray; and (4) VIP axons in the ventral and lateral white matter indicate that the spinal cord is supplied in part by VIP sources other than primary afferents.
Wheat germ agglutinin binding sites in the adult mouse cerebellum: Light and electron microscopic studies
Authors: Steindler Dennis A. , Cooper Nigel G. F.
Published: January 2005

The binding properties of derivatized wheat germ agglutinin (WGA) have been examined in fixed tissue sections from the adult mouse cerebellum and also in axonal tracing paradigms following cerebellar injections. The aim of these studies is to begin to distinguish the roles different binding sites may play in generating diverse biological activities which lead to neuronal uptake and axonal transport of lectins or glycoconjugates. Vibratome sections from aldehyde‐fixed cerebellum were incubated in N‐[acetyl‐3H] WGA or WGA conjugated to horseradish peroxidase (WGA‐HRP). Sections from this in vitro binding paradigm and those from cerebellar pressure injection eases using those tracers (in vivo binding paradigm) were processed for light microscopic autoradiography, histochemistry, and electron microscopy. Blocking experiments were also performed with various sugar haptens to confirm the binding specificity of these lectin preparations.

Light microscopy of lectin binding patterns within the cerebellar cortex has revealed that both derivatized WGA preparations bind most intensely to the molecular layer. Within the deep cerebellar nuclei, binding is unique and produces a punctate delineation of cell bodies and dendrites. Electron microscopy revealed that these binding sites are associated with glial processes which abut the plasma membrane of deep nuclei cells. Cerebellar WGA‐HRP injection sites contain labeled profiles involved in uptake and axonal transport of the labeled lectin (e.g., multivesicular and dense bodies) in addition to label associated with synapses, glia, undetermined components of the extracellular space, and neuronal plasma membranes. These sites are therefore presumed to possess a high affinity or capacity for binding derivatized WGA.

Binding studies performed here thus reveal, for the first time, the existence of discrete glial sites that display an extraordinary attraction for lectins such as WGA. The roles such glial glycoconjugates play in diverse biological activities including neuronal uptake and transport of macromolecules need further study.
Distribution of dynorphin and enkephalin peptides in the rat brain
Authors: Fallon James H. , Leslie Frances M.
Published: January 2005

The neuroanatomical distribution of dynorphin B‐like immunoreactivity (DYN‐B) was studied in the adult male and female albino rat. The distribution of DYN B in colchicine‐ and noncolchicine‐treated animals was also compared to that of another opioid peptide derived from the prodynorphin precursor dynorphin A (1‐8) (DYN 1‐8), and an opioid peptide derived from the proenkephalin precursor met‐enkephalin‐arg‐gly‐leu (MERGL). DYN B cell bodies were present in nonpyramidal cells of neo‐ and allocortices, medium‐sized cells of the caudate‐putamen, nucleus accumbens, lateral part of the central nucleus of the amygdala, bed nucleus of the stria terminalis, preoptic area, and in sectors of nearly every hypothalamic nucleus and area, medial pretectal area, and nucleus of the optic tract, periaqueductal gray, raphe nuclei, cuneiform nucleus, sagulum, retrorubral nucleus, peripeduncular nucleus, lateral terminal nucleus, pedunculopontine nucleus, mesencephalic trigeminal nucleus, parabigeminal nucleus, dorsal nucleus of the lateral lemniscus, lateral superior olivary nucleus, superior paraolivary nucleus, medial superior olivary nucleus, ventral nucleus of the trapezoid body, lateral dorsal tegmental nucleus, accessory trigeminal nucleus, solitary nucleus, nucleus ambiguus, paratrigeminal nucleus, area postrema, lateral reticular nucleus, and ventrolateral region of the reticular formation. Fiber systems are present that conform to many of the known output systems of these nuclei, including major descending pathways (e.g., striatonigral, striatopallidal, reticulospinal, hypothalamospinal pathways), short projection systems (e.g., mossy fibers in hippocampus, hypothalamo‐hypophyseal pathways), and local circuit pathways (e.g., in cortex, hypothalamus). The distribution of MERGL was, with a few notable exceptions, in the same nuclei as DYN B. From these neuroanatomical data, it appears that the dynorphin and enkephalin peptides are strategically located in brain regions that regulate extrapyramidal motor function, cardiovascular and water balance systems, eating, sensory processing, and pain perception.
Anatomy and physiology of saccadic burst neurons in the alert squirrel monkey. II. Inhibitory burst neurons
Authors: Strassman A. , Highstein S. M. , McCrea R. A.
Published: January 2005

Electrophysiological and intracellular labelling studies in the cat have identified a population of saccadic burst neurons in the medullary reticular formation that have an inhibitory, monosynaptic projection to the contralateral abducens nucleus. In the present study, intraaxonal recording and injection of horseradish peroxidase were used to identify and characterize the corresponding population of inhibitory burst neurons (IBNs) in the alert squirrel monkey. Squirrel monkey IBNs are located in the reticular formation ventral and caudal to the abducens nucleus and project contralaterally to the abducens. Additional contralateral projections are present to the vestibular nuclei, the nucleus prepositus, and the pontine and medullary reticular formation rostral and caudal to the abducens. All neurons fire a burst of spikes during saccades and are silent during fixation. In most neurons the burst begins 5‐15 msec before saccade onset. The number of spikes in the saccadic burst is linearly related to the amplitude of the component of the saccade in the neuron's on‐direction. Linear relationships also exist between burst duration and saccade duration and between firing frequency and instantaneous eye velocity. For all neurons, the on‐direction is in the ipsilateral hemifield, with a vertical component that may be either upward or downward. Neurons with projections to the vertically related descending and superior vestibular nuclei tend to have on‐directions with larger vertical components than neurons that lack these projections. These results, together with those on excitatory burst neurons reported in the preceding paper, demonstrate a reciprocal organization of burst neuron input to the abducens in the monkey similar to that found in the cat and indicate a major role for these neurons in generating the oculomotor activity in motoneurons as well as in other classes of premotor neurons.
Transganglionic degeneration in vibrissae innervating primary sensory neurons of the rat: A light and electron microscopic study
Authors: Arvidsson Jan
Published: January 2005

Previous studies have shown that transection of peripheral branches of primary sensory neurons leads to light microscopical degeneration argyrophilia and ultrastructural changes in the central termination areas of these neurons. This type of degeneration has been termed transganglionic degeneration TGD). In the present experiments TGD has been studied specifically in neurons innervating the rat vibrissae at the light and electron microscopic levels. Light microscopically, small amounts of degeneration argyro philia are observed in the magnocellular zone of the trigemimal subnucleus caudalis at 8‐14 days survival. At longer survival times there are substantial amounts of degeneration in this area. At the ultrastructural level the first signs of TGD are observed at 6 days survival, when some terminals show a small increase in electron density, loss of synaptic vesicles, and mitochondrial disintegration. Terminals showing a more advanced increase in electron density become common at 8 days survival, but few of them are still left at 14 days survival. Neurofilamentous terminals appear in small numbers 8‐14 days postoperatively. Various forms of degeneration in myelinated axons are observed from 8 days survival and are common also at 80 days survival. Electron‐dense axons are rather unfrequent, but more or less disrupted myelin sheaths containing disintegrated axoplasmic remnants and empty areas are common as well as extremely expanded myelin sheaths. Glial cells containing axonal and myelin debris are seen from 8 days survival and become a more common finding at longer survivals. A most striking finding 8‐10 days postoperatively is a complex relationship between glial cells and less darkened terminals, indicating phagocytosis before reaching an entirely darkened state. The findings clearly show that peripheral nerve transection leads to severe central alterations in a population of mechanoreceptor neurons innervating the vibrissae of the adult rat.
Gap‐junctional contacts of luminosity‐type horizontal cells in the carp retina: A novel pathway of signal conduction from the cell body to the axon terminal
Authors: Kouyama Nobuo , Watanabe Kosuke
Published: January 2005

L‐type horizontal cells (271) of the carp retina were studied with the aid of intracellular injections of Lucifer yellow and horseradish peroxidase (HRP). Coupling among these cells was revealed by passage of the dye out of the injected cell. Thick processes that crossed axons filled with Lucifer yellow also contained the stain. These thick processes appear to be the axon terminals of other horizontal cells. Serial reconstruction of an axon terminal by electron microscopy revealed two groups of elements connected to the axon terminal with putative gap junctions. One large‐diameter group was identified as axon terminals of other cells. From the results of the Lucifer dyecoupling experiments, the smaller‐diameter elements are thought to be the axons of other horizontal cells. Thus, the axon terminals of carp horizontal cells have putative gap junctional contacts not only with other axon terminals but also with the axons of other horizontal cells. This newly discovered connection could serve as a pathway for signal transfer between the cell body and the axon terminal of different horizontal cells.
Biochemical characterization of the major peanut‐agglutinin‐binding glycoproteins in vertebrate retinae
Authors: Hageman Gregory S. , Johnson Lincoln V.
Published: January 2005

Peanut agglutinin (PNA), a lectin that binds D‐galactose‐β (1→3) Nacetyl‐D‐galactosamine disaccharide linkages, selectively labels cone photoreceptors in the retinae of a variety of species. PNA binds consistently to domains of the interphotoreceptor matrix associated with cone, but not rod, inner and outer segments, to cone cell body and axonal membranes, to cone synaptic pedicles, and to portions of the inner plexiform layer. In order to begin the characterization of the molecular species responsible for conespecific PNA binding, chick, turkey, rat, dog, pig, monkey, and human retinal extracts were separated by SDS‐polyacrylamide gel electrophoresis and probed with peroxidase‐conjugated PNA.

The results reveal the presence of six major groups of PNA‐binding glycoproteins ranging from 30 to 88 kilodaltons. Most of these are shared by the seven species examined; however, some interspecies variation is present. Three groups, designated GP39/40, GP42/45, and GP60, are the most intensely labeled by PNA and are common to all species analyzed, while groups GP29/31 and GP88 are less intensely labeled and are present in most but not all of the species investigated. Labeling of the GP54 group is variable but is most consistently associated with extracts of rat and pig retinae. Trypsin treatment, which results in the loss of cone‐associated PNA binding in the interphotoreceptor matrix, causes a visually detectable reduction in three of the six groups of PNA‐binding glycoproteins in porcine retinal extracts. Of these, GP54 is the most sensitive, being undetectable on PNAstained blots after only 5 minutes of enzyme exposure; GP88 and GP45 are less sensitive but both are markedly reduced after 15 minutes of trypsinization. Trypsin‐sensitive molecules thus may be involved in the establishment of the cone‐specific domains of interphotoreceptor matrix identified by PNA binding. These, as well as the other groups of PNA‐binding molecules, are being utilized to develop more specific immunologic probes with which to further study of their distribution and function.
Accumulation of (3H)glycine by cone bipolar neurons in the cat retina
Authors: Cohen Ethan , Sterling Peter
Published: January 2005

Cone bipolar neurons in the cat retina were studied in serial sections prepared as electron microscope autoradiograms following intravitreal injection of (3H)glycine. The goal was to learn whether the cone bipolar types that accumulate glycine correspond to the types thought on other grounds to be inhibitory. About half of the cone bipolars in a given patch of retina showed specific accumulation of silver grains. The specificity of accumulation was similar to that shown by glycine‐accumulating amacrines. All of the cone bipolars arborizing in sublamina b accumulated glycine but none of the cone bipolars arborizing in sublamina a did so. The types of cone bipolars accumulating glycine did not match the types thought to be inhibitory. Cone bipolar types CBb1 and CBb2 both form gap junctions with the glycine‐accumulating AII amacrine, thus raising the possibility that glycine might accumulate in these cone bipolars by diffusion from the AII cell or vice versa. Thus it is logically impossible to tell which of these three cells contains a high‐affinity uptake mechanism for glycine and consequently which of the three might actually use glycine as a neurotransmitter.
Different neuron populations in the feline lateral cervical nucleus: A light and electron microscopic study with the retrograde axonal transport technique
Authors: Flink R. , Westman J.
Published: January 2005

A comparative light and electron microscopic study was made of the two major neuron populations in the feline lateral cervical nucleus (LCN) that have an ascending projection–namely, the cervicothalamic and cervicomesencephalic neurons. The small population of neurons in the LCN that remained unlabelled after extensive injections into all known areas of LCN termination was also investigated. The intra‐axonal retrograde tracing technique was employed and three different tracers were used: native horseradish peroxidase, horseradish peroxidase conjugated to wheat germ agglutinin, and cholera toxin subunit B (CTb). The diaminobenzidine and tetramethylbenzidine methods were used for the peroxidase reaction, and an immunocytochemical staining method with monoclonal antibodies was employed to localize CTb. The light microscopic cell count was performed on plasticembedded semithin (2 μm) sections, and a section‐embedding technique was used for sampling regions of interest for electron microscopy. The total number of neurons in the LCN was calculated to be 8,300, which is higher than numbers reported from other studies on frozen sections. It was concluded from control experiments that many neurons fail to counterstain in frozen sections. The average proportion of labelled cervicothalamic neurons was 94%, which accords with earlier reports. The frequency of labelled neurons projecting to the midbrain was 25–49%, depending on the method used. The highest number of labelled neurons was found with the immunocytochemical method with use of CTb as a tracer. In the electron microscopic study, the cell area, form factor, nuclear area, bouton covering ratio, mean appositional length of boutons, and bouton density were measured. There were no significant differences in these respects between the cervicothalamic and cervicomesencephalic neurons, but the unlabelled neurons differed significantly from the labelled ones, with a smaller somal area, a lower bouton covering ratio, and a larger relative nuclear area. The ascending neurons were scattered over the entire LCN, but the neurons that remained unlabelled after the extensive injections was found in its ventromedial part. It is suggested that these are interneurons.

In the light microscopic study of the animals injected with CTb, the ventromedial part of the LCN displayed labelled structures resembling terminals. Electron microscopic examination of the sections revealed boutons synapsing on unlabelled neurons and dendrites. Occasionally labelled neurons and dendrites were also contacted. These terminals, which were found both after thalamic and tectal injections, probably belong to the recurrent axon collaterals of the ascending neurons.