bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractElectrophysiological 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

AbstractPrevious 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

AbstractL‐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

AbstractPeanut 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

AbstractCone 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

AbstractA 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.
Bulbospinal projections in the primate: A light and electron microscopic study of a pain modulating system
Authors: Basbaum Allan I. , Ralston Diane D. , Ralston Henry J. 
Published: January 2005

AbstractThe projections of the nucleus raphe magnus (NRM) and the immediately adjacent reticular formation were studied in the macaque monkey following injections of the rostroventral medulla with 3H‐leucine and examination of the resultant labeled axons and terminals by light and electron microscopic autoradiography. Five monkeys had accurately placed injections, which resulted in fiber pathway labeling that coursed caudally, laterally, and dorsally to project to laminae I, II, and V of subnucleus caudalis of the trigeminal and then traveled in the dorsolateral funiculus of the cord and terminated in similar laminae of the spinal dorsal horn at cervical levels. The pathway was only lightly labeled caudal to the cervical enlargement and could not be readily discerned above background in the thoracic or lumbar cord.Electron microscopy revealed that axons and terminals serving this system constitute a heterogeneous population. Large‐diameter myelinated axons (3–6‐μm diameter), small myelinated axons (0.75–3‐μm diameter), and clusters of nonmyelinated axons were labeled. Terminals in laminae I, II, and V contained mixtures of clear round and granular vesicles or clear pleomorphic and granular vesicles or formed the central element in synaptic glomeruli. The labeled profiles formed asymmetrical or symmetrical synapses on medium and small dendrites; labeled axosomatic synapses were not observed. In rare instances there were contacts between labeled profiles and vesicle‐containing structures, which were probably dendritic, but whether the NRM axon was pre‐ or postsynaptic to such structures could not be determined.It was concluded that the NRM in the monkey is organized in a manner quite similar to that previously described in the cat. The wide variety of fiber types and synapti termials serving this system suggests that different classes of neurons participate in it, probably using several transmitter substances that result in varying postsynaptic effects on neurons located in the trigeminal complex and dorsal horn.
Microelectrode maps, myeloarchitecture, and cortical connections of three somatotopically organized representations of the body surface in the parietal cortex of squirrels
Authors: Krubitzer L. A. , Sesma M. A. , Kaas J. H. 
Published: January 2005

AbstractMicroelectrode mapping methods and anatomical procedures were combined in the same animals to reveal the cortical connections of three architectonically distinct representations of the body surface in the somatosensory cortex of grey squirrels. In individual experiments, microelectrode multiunit recordings were used to determine the somatotopic organization of regions of the cortex and to identify sites for injections of the anatomical tracer, wheat germ agglutinin conjugated to horseradish peroxidase. After the brains were perfused, the cortex was separated from the brainstem, flattened, and cut parallel to the flattened surface to facilitate comparisons of areal connection patterns, physiological data, and architectonic subdivisions.Recordings in the primary (S‐I) and secondary (S‐II) somatosensory fields confirmed earlier descriptions of the somatotopic organization of these fields (Sur et al.: J. Comp. Neurol 179:425–450, '78; Nelson et al.: J. Comp. Neurol 184:473–490, '79). In addition, recordings in the cortex caudal to S‐I and ventral to S‐II revealed a third representation of the body surface in parietal cortex, the parietal ventral area (PV). Neurons in PV were responsive to light tactile stimulation of skin and hairs. Multiple unit receptive fields of neurons in PV were larger than those for neurons in S‐I but similar in size to those for neurons in S‐II. PV represented the contralateral body surface in a somatotopic manner that can be roughly characterized as an inverted “homunculus” with the limbs directed medially, the trunk located ventrally, and the face congruent with the representations of the upper lip and nose in S‐I. Neurons in some electrode penetrations in PV were also responsive to auditory clicks.Microlesions placed at physiologically determined borders allowed all three somatic representations to be related to myeloarchitectonically defined fields. S‐I was architectonically distinct as a densely myelinated region. Within S‐I, a lightly myelinated oval of the cortex between the representation of the hand and face, the “unresponsive zone” (Sur et al.: J. Comp. Neurol 179:425‐450, '78), was an easily recognized landmark. S‐II and PV corresponded to less densely myelinated fields. Other subdivisions such as motor cortex, primary auditory cortex, and visual areas 17 and 18 were distinguished.