bluuebunny/crossref_metadata_2025 huggingface dataset:
Serotoninergic innervation of the dorsal column nuclei and its relation to cytoarchitectonic subdivisions: An immunohistochemical study in cats and monkeys (Aotus trivirgatus)
Authors: Blomqvist Anders , Broman Jonas
Published: January 2005

The serotoninergic innervation of the dorsal column nuclei (DCN) was investigated in cats and owl monkeys (Aotus trivirgatus) with immunohistochemical methods. A dense network of serotonin‐immunoreactive fibers was present in the reticular regions of DCN in cats, and in the pars triangularis of the cuneate nucleus and the peripheral and caudal regions of the gracile nucleus in owl monkeys. The cat's cluster regions and the monkey's rotund regions were more sparsely innervated. Electron microscopic examination showed that the labeled fibers were thin and unmyelinated. Vesicle‐containing, terminal‐like structures were small. They were in contact with dendrites, other terminals and cell bodies, but synapses were rare.

The results demonstrate that the serotoninergic projection to the DCN in both cats and owl monkeys is heterogeneously distributed in a pattern that is faithfully related to the cytoarchitectonic subdivisions of the DCN. The densely innervated reticular regions in the DCN of cats and the corresponding regions in monkeys are predominantly involved in the processing of sensory information to the cerebellum, either directly, or indirectly through projections to the inferior olive, pontine gray, tectum, pretectum, red nucleus, or zona incerta. Thus, the present findings suggest that the serotoninergic innervation of the DCN is primarily related to the DCN's involvement in motor functions. © 1993 Wiley‐Liss, Inc.
Distribution of noradrenaline‐immunoreactivity in the brain of the mormyrid teleost Gnathonemus petersii
Authors: Meek J. , Joosten H. W. J. , Hafmans T. G. M.
Published: January 2005

The distribution of noradrenaline‐immunoreactivity in the brain of the mormyrid fish Gnathonemus petersii was studied in order to evaluate the noradrenergic innervation of a number of specialized mormyrid brain regions, including electrosensory centers and a gigantocerebellum. Noradrenaline‐immunoreactive (NAi) neurons occur in the hypothalamic paraventricular organ (PVO), the locus coeruleus, and the caudal rhombencephalon. In the PVO, NAi cerebrospinal fluid (CSF)‐contacting neurons are located in the same regions where dopamine‐ and serotonin‐containing CSF contacting neurons occur. The locus coeruleus consists, on each side, of at least 30 rather large NAi neurons with ventrolaterally directed dendrites and dorsolaterally coursing axons. In the caudal rhombencephalon, NAi neurons are located in the transition region between the ventromedial motor zone and the dorsolateral sensory zone.

The density of NAi fibers is very high in the efferent tract of the locus coeruleus, the medial forebrain bundle, and two telencephalic, one preoptic, and one rhombencephalic subependymal axonal plexus. A marked NAi innervation is present in the dorsomedial and ventral telencephalon, the preoptic region, periventricular hypothalamic and thalamic regions, the midbrain tectum, cerebellar granular layers, the electrosensory lateral line lobe, the rhombencephalic transition region between the sensory and motor zones, and the area postrema. Other regions are more sparsely innervated by NAi fibers, but regions completely devoid of NAi fibers were not observed. Interestingly, NAi fibers form large club endings in some subdivisions of the precerebellar nucleus lateralis valvulae, and parallel fibers in the cerebellar granular layer.

Comparison with the distribution of NAi or dopamine‐β‐hydroxylase‐immunoreactivity in other species shows that all teleosts studied to date have noradrenergic cells in the locus coeruleus and the caudal rhombencephalon. However, NAi CSF‐contacting PVO cells have been described only in the teleost Gnathonemus petersii and the lizard Gekko gecko (Smeets and Steinbusch: J. Comp. Neurol. 285:453–466, 89). It is possible that they might pick up catecholamines as well as serotonin from the CSF, into which monoamines might be released by telencephalic and preoptic subependymal axonal plexuses. © 1993 Wiley‐Liss, Inc.
Spinal neurogenesis and axon projection: A correlative study in the rat
Authors: Nandi Kailas N. , Knight David S. , Beal John A.
Published: January 2005

The purpose of the present study was to determine the relationship between the duration of a spinal neuron's neurogenic period and the length of its axon or level of projection. Spinal segment L1 was chosen for examination and neurons were divided into four projection groups: (1) supraspinal projection (SSp), (2) long ascending propriospinal (LAPr), (3) short ascending propriospinal (SAPr), and (4) descending propriospinal (DPr). To determine the duration of the neurogenic period for each group, 3H‐thymidine was administered to fetal rats during the proliferative period for spinal neuroblasts on one of embryonic (E) days E13 through E16. Between 50 and 100 days after birth neurons in each group were labeled with the retrograde fluorescent tracer Fluoro‐Gold. To demonstrate nerve cells with SSp projections, spinal cords were hemisected at spinal segment C3 in one group of animals and Fluoro‐Gold was applied to the sectioned surface of the cord. Three additional sets of animals were used to label nerve cells with LAPr, SAPr, and DPr projections by injecting Fluoro‐Gold into the gray matter at spinal segments C6, T12, and L5, respectively. Neurons labeled with both Fluoro‐Gold and 3H‐thymidine and neurons labeled with Fluoro‐Gold alone in each animal in each group were counted and the data statistically analyzed. Results showed that within each spinal lamina neurons with different projections were generated, i.e., completed cell division, at significantly different rates. Neurons with the longest axons, those with SSP projections, were generated first. These were followed by those with LAPr projections, and finally those with SAPr and DPr projections. In most laminae there was no significant difference between the neurogenic periods of rostrally projecting short propriospinal (SAPr) neurons versus caudally projecting short propriospinal (DPr) neurons. It was concluded that the duration of the neurogenic period for a given group of neurons within each spinal lamina is inversely related to the distance between the nerve cell and its projection site regardless of the direction of its projection. © 1993 Wiley‐Liss, Inc.
Carbocyanine dye labeling reveals a new motor nucleus in octopus brain
Authors: Robertson J. David , Schwartz Owen M. , Lee Psyche
Published: January 2005

This work aims at a better understanding of the organization of the brain of Octopus vulgaris, emphasizing the touch and visual learning centers. We injected the carbocyanine dye, DiI, into the cerebrobrachial connectives and, separately, into the brachial nerves of living octopuses. In both experiments, retrogradely transported granules of DiI appeared in motor neurons in the superior buccal, posterior buccal and subvertical lobes and in a hitherto unsuspected motor nucleus of several hundred neurons in the posterior dorsal basal and median basal lobes.

In addition we labeled afferent fibers by injecting DiI into the caudal (sensory) division of the cerebrobrachial connective on one side; the label spread throughout the superior buccal, posterior buccal and the lateral and median inferior frontal lobes mainly on the injected side. It extended through the cerebral tract into the subvertical lobe, into the superior frontal lobe through the interfrontal tract, through the posterior buccal commissure into the opposite posterior buccal lobe and into the median inferior frontal lobe.

The work suggests a new function for the posterior dorsal and median basal lobes, which are shown for the first time to project through the inferior frontal lobe system into the brachial nerves. In addition it represents the first full report of the successful use of the carbocyanine dyes DiI and DiO for labeling nerve tissue in a live invertebrate animal. © 1993 Wiley‐Liss, Inc.
Mapping of octopamine‐immunoreactive neurons in the central nervous system of the lobster
Authors: Schneider Henning , Trimmer Barry A. , Rapus Jürgen , Eckert Manfred , Valentine Doreen E. , Kravitz Edward A.
Published: January 2005

It has been suggested that serotonin and octopamine serve important roles in behavioral regulation in lobsters. In this paper the locations of octopamine‐immunoreactive neurons were mapped in wholemount preparations of the ventral nerve cord of 4th stage lobster (Homarus americanus) larvae. Approximately 86 neurons were found, distributed as follows: brain, 12; circumesophageal ganglia, 2; subesophageal ganglion, 38; thoracic ganglia, 6 each; and 4th and 5th abdominal ganglia, 2 each. All the octopamine‐immunoreactive neurons are paired and located along the midline. Of the 86 neurons, 28 were identified as neurosecretory, and 26 as intersegmental ascending thoracic, ascending abdominal, or descending interneurons. The neurosecretory system is arranged segmentally and located entirely within the thoracic and subesophageal neuromeres with extensive terminal fields of endings along 2nd thoracic and subesophageal nerve roots. This set of neurons shares the features of central and peripheral endings with 2 pairs of large serotonin‐containing neurosecretory neurons found in the fifth thoracic and first abdominal ganglia. The intersegmental neurons include: (1) two cells in the brain and 2 pairs of cells in the 3rd and 4th neuromeres of the subesophageal ganglion, which project to the 6th abdominal ganglion; (2) a segmentally organized group of ascending internurons found in the subesophageal and in all thoracic ganglia; and (3) pairs of ascending interneurons found in the 4th and 5th ganglia in the abdominal nerve cord. By means of a biochemical assay, the cell bodies of octopamine‐immunoreactive neurosecretory cells in the thoracic segment of the nerve cord were found to contain 40–100 fmol of octopamine, while control neurons had none. © 1993 Wiley‐Liss, Inc.
Connections between the deutocerebrum and the protocerebrum, and neuroanatomy of several classes of deutocerebral projection neurons in the brain of male Periplaneta americana
Authors: Malun Dagmar , Waldow Ulrich , Kraus Dieter , Boeckh Jürgen
Published: January 2005

The topography and neuroanatomy of fibers connecting the deutocerebrum to the protocerebrum in the brain of the American cockroach Periplaneta americana were investigated by staining single or multiple deutocerebral neurons with cobalt, Lucifer Yellow, or biocytin. Five tracts are distinguished on the basis of their routes from origins in the antennal lobe to the protocerebral neuropil: the inner antenno‐cerebral tract (IACT); antenno‐cerebral tracts II, III, and IV (ACT II, III, IV), and the outer antenno‐cereral tract (OACT). These tracts are largely composed of the axons of four classes of deutocerebral projection neurons, which have been identified morphologically; the neuronal arborizations in the glomeruli of the antennal lobe and in the protocerebral projection regions have been examined. Projection neurons with processes in the inner antenno‐cerebral tract and in the antenno‐cerebral tract II each innervate a single glomerulus in the antennal lobe, and both types have terminals in the calyces of the mushroom bodies and in the lateral lobe of the protocerebrum. The axons of pheromone‐sensitive projection neurons with dendritic trees in the male‐specific macroglomerulus seem to run exclusively in the inner antenno‐cerebral tract. Subgroups of these pheromone sensitive neurons differ in relative sensitivity to the two female attractant components as well as in the arborization pattern of their dendrites in the macroglomerulus. The projection neurons of two other classes each innervate many glomeruli in the antennal lobe, those of one class sending their axons into the protocerebrum in the antenno‐cerebral tract IV and the other, in the outer antenno‐cerebral tract. The neurons of antenno‐cerebral tract IV innervate not only the mushroom body calyces and the lateral lobe but also neuropil regions not previously described in the cockroach. Neurons with axons in the outer antenno‐cerebral tract have no terminals in the calyces but innervate the lateral lobe and the neuropil surrounding the tract.

The morphological findings presented here show that, in addition to the tracts previously documented in the cockroach brain, there are other, presumably olfactory, connections between the deutocerebrum and the protocerebrum. © 1993 Wiley‐Liss, Inc.
A method for unbiased and efficient estimation of number and mean volume of specified neuron subtypes in rat dorsal root ganglion
Authors: Tandrup Trine
Published: January 2005

By means of unbiased stereological principles and systematic sampling techniques, the number, the mean volume, and the distribution of neuron volumes of the A‐ and B‐cells of the dorsal root ganglion have been estimated. The number of each neuron type was estimated from the product of the volume of the ganglion, obtained with the Cavalieri principle on serial sections of the ganglion, and the numerical density, obtained with the Cavalieri principle on serial sections of the ganglion, and the numerical density, obtained with optical disectors on the same sections. The mean volume of the cell bodies of each type was estimated by applying the nucleator technique to the neurons sampled with the optical disectors. The precision of the estimate in each animal was evaluated on the basis of the variation between animals. An optimal sampling scheme is described by which estimates of the total number, the mean volume, and the distribution of cell body volumes can be obtained in about 8 hours.

In the right fifth lumbar dorsal root ganglion taken from four mature, male Wistar rats, the mean total number of neurons was found to be 17,900. Of these, 28% were A‐cells, with a mean cell body volume of 53,400 μm3, and 70% were B‐cells, with a mean cell body volume of 8,540 μm3. There was a considerable overlap between the volume distributions of the two cell types © Wiley‐Liss, Inc.
Correlation between the receptive fields of locust interneurons, their dendritic morphology, and the central projections of mechanosensory neurons
Authors: Burrows Malcolm , Newland Philip L.
Published: January 2005

The relationships between the morphology and receptive fields of local and intersegmental interneurons that process mechanosensory information from a hindleg of the locust have been analysed. Sensory neurons from tactile hairs project to ventral areas of neuropil in the metathoracic ganglion where they form a 3‐dimensional somatotopic map of a hindleg. By contrast, sensory neurons from a proprioceptor at the femoro‐tibial joint (the femoral chordotonal organ) project to lateral and more intermediate areas of neuropil and have no branches in the most ventral regions of neuropil.

Particular local and intersegmental interneurons respond to stimulation of specific arrays of hairs on a hindleg, or to movements of particular joints. Their receptive fields are defined, in part, by the patterns of excitatory, monosynaptic connections made by these afferents. Each interneuron has a characteristic receptive field and a characteristic morphology defined by its array of branches in the regions of neuropil containing the projections of the afferents that provide its monosynaptic inputs.

Interneurons with inputs exclusively from tactile hairs have branches in the most ventral regions of neuropil, while those with exclusively proprioceptive inputs have branches only in more intermediate levels of neuropil. Interneurons with extensive receptive fields from tactile hairs also have extensive areas of branching within the ventral neuropil. Interneurons with receptive fields restricted to particular regions of the leg have branches restricted to the ventral region of neuropil containing the projections of afferents from that part of the leg. Thus, interneurons with inputs only from hairs on the tarsus have branches in the posterior region of neuropil corresponding to the projections of the tarsal afferents, while interneurons with receptive fields on the femur have branches in more anterior regions of neuropil corresponding to the projections of the femoral hair afferents. Interneurons with receptive fields on the tibia have branches in neuropil between the tarsal and femoral projections. © 1993 Wiley‐Liss, Inc.
Distribution of glial fibrillary acidic protein‐immunopositive structures in the brain of the domestic chicken (Gallus domesticus)
Authors: Kálmán Mihály , Székely Andrea D. , Csillag András
Published: January 2005

The present study is the first comprehensive mapping of glial fibrillary acidic protein (GFAP)‐immunopositive structures in the avian brain. Two main types of GFAP‐immunopositive elements were observed: (1) nonbranching fibers, occasionally twisted or varicose, and (2) star‐shaped cells. Long immunostained fibers orignate from the lateral ventricle to form three bundles. Fibers of the dorsal group, emanating from the dorsal/lateral corner of the ventricle, course in lateral, anterior, and ventral directions forming a semidome, which separates the outer pallial (lateral cortical) regions from the underlying striatal mass. The middle group of fibers is directed anteriorly and laterally corresponding to the laminae frontales superior and suprema. The ventral fiber bundle is conical and traverses the lobus parolfactorius, crossing also the lamina medullaris dorsalis (the latter consisting mainly of star‐shaped cells). The hippocampus, septum, and hypothalamus also contain straight radial fibers. In some areas, given their variable orientation, the fibers cannot be regarded as merely persisting radial glia. In the telencephalon, the nuclei basalis, accumbens, ectostriatum, paleostriatum primitivum, and the ventral paleostriatum are particularly rich in GFAP‐positive cells, whereas the neostriatum, hyperstriatum, and paleostriatum augmentatum are almost devoid of GFAP labelling. Certain nuclei of the thalamus and the lower brainstem are conspicuous by their low levels of GFAP immunoreactivity. The Bergmann glia were GFAP‐immunonegative.
Geometry of the representation of the visual field on the superior colliculus of the wallaby (Macropus eugenii). I. Normal projection
Authors: Mark R. F. , James A. C. , Sheng X.‐M.
Published: January 2005

In 13 wallabies (Macropus eugenii, the tammar), microelectrode recordings of the activity of units in the superficial layers of the superior colliculus in response to a flashing light spot were used to make a map of the spatial location of their receptive fields. This article describes the projection of a normal eye to the contralateral colliculus. Ten of the 13 animals had one rotated eye and these projections are analysed in the accompanying paper (James et al., this issue). Units responded briskly to the stimulus at light on and off and had receptive fields about 5° across. The centres of receptive fields from a regular array of recording points on the colliculus were plotted with a perimeter and fitted to a flattened representation of the colliculus according to a spline technique. The visual field of each colliculus extends from 25° ipsilateral to the vertical meridian to 120° temporal contralaterally. The lines of isoazimuth are regularly spaced and paralled and run mediolaterally on the colliculus. The horizon is represented by a line running rostrocaudally and the parallels are more widely spaced near the horizon and become compressed in the superior and inferior fields. The variation of areal magnification factor fits the distribution of density of retinal ganglion cells very well. Anisotropy of the projection means that the increased ganglion cell density of the retinal visual streak is entirely accommodated by magnification in the vertical direction, while the magnification of the azimuthal projection is equal over the whole field. No responses were recorded from the ipsilateral eye even though anatomically there is a direct retinal ipsilateral projection.
Numbers of neurons in the developing principal sensory nucleus of the trigeminal nerve: Enhanced survival of early‐generated neurons over late‐generated neurons
Authors: Miller Michael W. , Al‐Ghoul Walid M.
Published: January 2005

The overproduction and subsequent death of neurons is a common phenomenon in the developing vertebrate central nervous system (CNS). We tested the hypothesis that the survival of a neuronal subpopulation is related to its time of origin. Neuronal survival was examined in a well‐defined CNS structure, the principal sensory nucleus of the trigeminal nerve (PSN) of the rat. The changes in the total number of PSN neurons and in the numbers of early‐ and late‐generated neurons (i.e., neurons heavily labeled by a single injection of [3H]thymidine on G12 or G14, respectively) between gestational day (G) 16 and postnatal day (P) 10 were determined. The total number of neurons in the PSN rose prenatally to a maximum of 40,600 on G18.5. The increase in neuronal number correlates to the period of migration. More than half of the neurons that successfully migrated to the PSN were lost by P10. The patterns for the changes in the numbers of early‐ and late‐generated neurons were similar; however, there were significant differences between the two subpopulations. The maximum number of early‐generated neurons (4,250) was attained on G18.2 and subsequèntly 58.9% of these neurons were lost. In contrast, the maximum number of late‐generated neurons (5,050) was attained on G20.0 and 66.6% of these neurons were lost by P10. Therefore, it appears that the survivability of early generated neurons is greater than for late‐generated neurons. This enhanced survivability presumably results from a competitive advantage that early‐generated neurons have for forming synapses or gaining access to trophic factor(s) that are in limited supply.
Quantitative phylogenetic constancy of cerebellar purkinje cell morphological complexity
Authors: Smith Thomas G. , Brauer Kurt , Reichenbach Andreas
Published: January 2005

Golgi‐stained material of cerebellar cortices from 17 species was examined by measuring the fractal dimensions of the borders of Purkinje cells, which is a quantitative, objective measure of morphological complexity. Nine species (from birds to man) were chosen for a comparison with ANOVA and no statistically significant differences were found in their fractal dimensions. In contrast, a wide range of differences was found in the membrane areas across species lines. The Sholl coefficient, a measure of branch formation and temination and termination away from the soma, showed no consistent pattern for each cell. We interpret our results as indicating a constancy in morphological cellular complexity of Purkinje cells during late evolutionary time. © 1993 Wiley‐Liss, Inc.
Localization of D2 dopamine receptors in vertebrate retinae with anti‐peptide antibodies
Authors: Wagner Hans‐Joachim , Luo Bao‐Guo , Ariano Marjorie A. , Sibley David R. , Stell William K.
Published: January 2005

Dopamine plays an important role in modulating various aspects of retinal signal processing. The morphology of dopaminergic neurons and its physiological effects are well characterized. Two classes of receptor molecules (D1 and D2) were shown pharmacologically to mediate specific actions, with differences between individual groups of vertebrates. In an attempt to better understand dopaminergic mechanisms at the cellular level, we used antisera against D2 receptors and investigated the localization of the dopamine D2 receptor in the retinae of rat, rabbit, cow, chick, turtle, frog, and two fish species with immunofluorescence techniques. Antisera were raised in rabbits to two oligopeptides predicted from rat D2 receptor cDNA; one specific for the splice‐variant insertion in the third cytoplasmic loop and the other directed towards the extracellular amino terminal region shared by both short and long isoforms. Preadsorption with the synthetic peptide resulted in a significant reduction of label, indicating the presence of specific binding in all species except turtle and goldfish. The pattern of labelling produced by the two antisera was essentially identical; however, the staining obtained with antiserum to the extracellular motif was always more intense. Specific staining was present in photoreceptor inner and outer segments, and in the outer and inner plexiform layers of all species. In mammals and chick, strongly fluorescent perikarya were observed in the ganglion cell layer and at the proximal margin of the inner nuclear layer. Label may be present in the pigment epithelium but could not be established beyond doubt. This pattern of labelling is in accordance with previous observations on D2 receptor localization by means of radioactive ligand binding and in situ hybridization techniques. It suggests that retinal dopamine acts as a neuromodulator as well as a transmitter. In the distal retina, it may reach its targets via diffusion over considerable distances, even crossing the outer limiting membrane; in the inner and outer plexiform layers, conventional synaptic transmission seems to coexist with paracrine addressing of more distant targets, and D2 receptors are expressed by both amacrine and ganglion cells. © 1993 Wiley‐Liss, Inc.
Corticofugal projections to the vestibular nuclei in squirrel monkeys: Further evidence of multiple cortical vestibular fields
Authors: Akbarian S. , Grüsser O.‐J. , Guldin W. O.
Published: January 2005

Single‐ and multiple‐unit recordings were made from nerve cells located in the different nuclei of the brainstem vestibular nuclear complex (VNC) of anaesthetized squirrel monkeys (Saimiri sciureus) by conventional sterotaxic techniques. After neurons responding to semicircular canal stimulation in a yaw, roll, or pitch direction or to otholith stimulation were identified, small amounts of retrograde tracer substances were deposited at the recording sites. Up to three different tracers were administered to different parts of the VNC in the same animal (Fast Blue, HRP‐WGA, and Rhodamine‐dextranes). After adequate survival times, the animals were sacrificed. Following histological processing, the cortical grey matter was screened systematically for cells labelled with the retrograde tracers (fluorescence microscopy or light microscopy for HRP processing). Labelled nerve cells which clearly project to the VNC directly were found predominantly in the cytoarchitectonic layer 5 of seven different cortical areas: (1) The parieto‐insular vestibular cortex PIVC, which in squirrel monkeys consists mainly of the medial area Ri and parts of the anterior area Ig; (2) area 7ant, which presumably corresponds to the macaque area 2v; (3) area 3aV, a vestibular field of area 3a; (4) the temporal area T3 bordering on area Ri; (5) the premotor area 6a; and (6, 7) the areas 6c and 23c of the anterior cingulate cortex. The PIVC, area 7ant, and area 3aV form the “inner cortical vestibular circuit” (Guldin et al.: J. Comp. Neurol. 326:375–401, '92) while the other cortical areas mentioned also have direct projections to the structures of the inner cortical vestibular circuit. It is speculated that the direct projections of the cortical vestibular structures to the brainstem vestibular nuclei regulate the vestibulo‐ocular, the vestibulo‐spinal, and the optokinetic reflexes mediated through the VNC, thus preventing counteractions of these reflexes during voluntary, goal‐directed head movements or locomotion. © 1993 Wiley‐Liss, Inc.
Local origins of some GABAergic projections to the paraventricular and supraoptic nuclei of the hypothalamus in the rat
Authors: Roland B. L. , Sawchenko P. E.
Published: January 2005

Axonal transport and immunohistochemical methods were used to characterize the organization of glutamic acid decarboxylase‐immunoreactive (GAD‐ir) projections to the paraventricular (PVH) and supraoptic (SO) nuclei of the hypothalamus in the rat. In line with prior reports, GAD‐ir varicosities were found to be densely and quite uniformly distributed throughout the hypothalamus, including the PVH and the SO. Nonetheless, the periventricular part of the PVH was consistently found to contain a disproportionately high density of GAD‐ir elements. Small crystalline implants of the retrograde tracer, true blue, into the PVH labeled GAD‐ir cells in the anterior perifornical region, portions of the anterior hypothalamic area immediately ventral to the PVH, a region just dorsal to the rostral SO and extending caudomedially over the optic chiasm and tract, and within the anterior one‐third of the PVH itself. Because possible uptake of retrograde tracer by local dendritic processes might have yielded false positive filling of nearby GAD‐ir cells, anterograde transport, Phaseolus vulgaris‐leucoagglutinin, and combined anterograde transport‐immunohistochemical methods were used to attempt to confirm these four putative local sources of GAD‐ir inputs. Tracer injections in each of the above mentioned regions labeled sparse to moderate axonal projections to the PVH, which ramified preferentially in the parvicellular division of the nucleus. Projections to the magnocellular division of the PVH and the SO were generally sparse and inconsistently observed in this material. A variable, and generally small, proportion of anterogradely labeled axons and terminals in the PVH also displayed GAD‐ir. These results suggest that GABAergic projections to visceromotor cell types in the PVH and SO arise, at least in part, from several diffusely distributed local sources. The fact that these afferents were found to terminate preferentially in the parvicellular division of the PVH makes it likely that additional sources of GABAergic projections to the magnocellular neurosecretory system remain to be identified. Peri‐ and intranuclear GABAergic neurons could provide an intermediary by which documented (and generally inhibitory) limbic system influences on neuroendocrine function are exerted. © 1993 Wiley‐Liss, Inc.
Choline acetyltransferase immunoreactive neurons innervating labyrinthine and lateral line sense organs in amphibians
Authors: González A. , Meredith G. E. , Roberts B. L.
Published: January 2005

The goal of the present study was to investigate aspects of the central organization of the neurons belonging to the octavolateralis efferent system of amphibians. The perikarya of three genera, Pleurodeles, Xenopus, and Discoglossus, were located in the brainstem by applying retrograde to the appropriate cranial nerves and choline acetyltransferase immunohistochemistry was used to identify cholinergic neurons.

The efferent neurons supplying lateral line (Pleurodeles, Xenopus) and labyrinthine (Pleurodeles, Xenopus, and Discoglossus) end organs were found to intermingle in a single octavolateralis efferent nucleus. The neurons lie bilateral to the labelled nerves in Pleurodeles and ipsilateral in Xenopus and Discoglossus. Separate labelling of the anterior and posterior octavus rami provided no evidence for distinct groupings of efferent neurons that could be associated with auditory and vestibular end organs. In all three species many if not all octavolateral efferent neurons displayed immunoreactivity for choline acetyltransferase. They could be distinguished from the cholinergic facial motoneurons, with which they sometimes intermingle, on the basis of either their distinctive size and shape (Pleurodeles, Xenopus) or their location (Discoglossus). Double labelling in Xenopus confirmed the cholinergic nature of the efferent neurons. © 1993 Wiley‐Liss, Inc.
Leucine5‐enkephalin afferents to midbrain dopaminergic neurons: Light and electron microscopic examination
Authors: Liang Chang‐Lin , Kozlowski Gerald P. , German Dwight C.
Published: January 2005

The relationship between leucine5‐enkephalin‐containing nerve terminals and midbrain dopaminergic neurons was studied in the adult rat by light and electron microscopy. For light microscopy, alternate midbrain sections were immunostained with rabbit polyclonal antibodies against leucine5‐enkephalin and tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique. Leucine5‐enkephalin stained fibers and terminals were observed with varying density in the retrorubral field (dopaminergic nucleus A8 region), substantia nigra pars compacta (dopaminergic nucleus A9 region), and ventral tegmental area and related nuclei (dopaminergic nucleus A10 region). For electron microscopy, midbrain sections were immunostained with a mouse monoclonal antibody against leucine5‐enkephalin and a rabbit polyclonal antibody against tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique and silver‐intensified colloidal gold reactions, respectively. The nucleus A10 area was examined at the electron microscopic level, and there were (a) both symmetric (75%) and asymmetric (25%) synapses made between leucine5‐enkephalin axon terminals and dopaminergic dendrites, and also synaptic contacts with unlabeled dendrites; (b) leucine5‐enkephalin synaptic contacts with dopaminergic dendrites that were covered with astrocytic membranes; and (c) leucine5‐enkephalin appositions with unlabeled nerve terminals that made synaptic contacts with dopaminergic dendrites, suggestive of axo‐axonic connections. These findings provide the structural basis for both direct and indirect control of A10 dopaminergic neurons by enkephalin‐containing nerve terminals. © 1993 Wiley‐Liss, Inc.
Immunocytochemical analysis of a novel carbohydrate differentiation antigen (CDA‐3C2) associated with olfactory and otic systems during embryogenesis in the rat
Authors: Prouty Stephen M. , Levitt Pat
Published: January 2005

Carbohydrate differentiation antigens are known to display specific patterns of expression during mammalian development and are thought to participate in significant morphogenetic events. In the present study, two monoclonal antibodies that react with a novel carbohydrate differentiation antigen (CDA‐3C2) were used to analyze, by light microscopy, the spatiotemporal distribution of this unique high molecular weight antigen during embryogenesis in the rat. Correlative analysis of the development of peripheral neural structures, in which CDA‐3C2 was expressed, was carried out with an anti‐neurofilament antibody. Enzymatic digestion, combined with Western blots, reveal that the CDA‐3C2 epitope is a carbohydrate which is carried on a high molecular weight glycoprotein with a mass of greater than 1 million Daltons. Characteristic of carbohydrate antigens, immunoreactivity was found in several distinct cellular patterns: only along the apical border of cells, along lateral and basal membranes of cells, and extracellular‐like staining in the mesenchyme. During neurulation, CDA‐3C2 showed differential staining in the ectoderm, distinguishing lateral from neural regions. Following closure of the neural tube, there was a striking specificity of expression of CDA‐3C2 in the periphery, found almost exclusively in olfactory and otic epithelial structures. While CDA‐3C2 is found in placode‐derived tissues that subserve sensory transduction, it appears to be primarily associated with the supportive cells (and their secretions) in both otic and olfactory regions and less so with the sensory cells. The data suggest that a unique carbohydrate antigen on a large macromolecule may play a role in neurulation and/or morphogenesis of the placode‐derived otic and olfactory structures. © Wiley‐Liss, Inc.
Developmental study of GnRH neuronal projections to the medial basal hypothalamus of the male Djungarian hamster
Authors: Buchanan Kevin L. , Yellon Steven M.
Published: January 2005

The present study in the male Djungarian hamster determined the neuroanatomical distribution and morphology of gonadotropin‐releasing hormone (GnRH) neurons which innervate the medial basal hypothalamus during sexual maturation. Prepubertal, peripubertal, and postpubertal males were perfused, brains were removed, and crystals of the fluorescent tract tracer, DiI, were implanted directly into the median eminence of the brain. Eight weeks later, brains were sectioned and processed for GnRH immunofluorescence. At all ages, GnRH cell bodies were bipolar or unipolar; both subtypes were labeled with DiI in proportion to their respective numbers in each brain region. GnRH perikarya were distributed in a diffuse ventromedial continuum from the septum through the anterior hypothalamus. In prepubertal males, DiI was present in the majority of GnRH neurons (54% of total) that were located in brain regions rostral to and including the medial preoptic area. In lateral and caudal brain areas, fewer GnRH perikarya contained DiI (28% of total or less). With sexual maturation, fewer GnRH somata were labeled with DiI in areas rostral to the hypothalamus. The data suggest that bipolar and unipolar GnRH neurons in the forebrain, rostral to the preoptic area, are major contributors to the GnRH innervation of the median eminence in the male Djungarian hamster. With the onset of puberty, the finding that decreasing numbers of GnRH perikarya directly project to the medial basal hypothalamus suggests that fewer GnRH neurons constitute the final common pathway that controls gonadotropin secretion. © 1993 Wiley‐Liss, Inc.
The differentiation between neuroglia and connective tissue sheath in insect ganglia revisited: The neural lamella and perineurial sheath cells are absent in a mesodermless mutant of Drosophila
Authors: Edwards John S. , Swales Lesley S. , Bate Michael
Published: January 2005

Two morphogenetic mutations, twist and Delta, that affect the embryonic development of Drosophila in known ways were used to examine the derivation and function of the outer layers of the central nervous system (CNS). Both the extracellular neural lamella, which ensheaths the CNS, and its source, the underlying perineurial sheath cell layer, fail to develop in Drosophila embryos that are homozygous for a loss of function mutation in the twist gene, and which thus lack mesodermal derivatives. The cell layer immediately below the perineurial sheath cells, here termed barrier glial cells, constitute the ion permeability barrier in wild‐type embryos. They are present in twist mutant embryos, appear to be normal at the ultrastructural level, and function as a blood‐brain ion barrier.

The apparent derivation of perineurial sheath cells from mesodermal precursors distinguishes them from neurons, glia and other nonneural components of the CNS, such as tracheae, all of which are of ectodermal origin. We confirm Scharrer's interpretation of the relationship between the perineurium and underlying neuroglia.

In embryos homozygous for the neurogenic mutant Delta, an embryonic lethal in which excess ventral blastoderm gives rise to neuroblasts, the CNS forms as an amorphous cell mass, with discontinuous perineurial sheath and barrier glial cell layers. We propose that the cell mass is permeable to lanthanum ions and fails to form a blood‐brain barrier because volume growth prevents the formation of continuous surface cell layers. © 1993 Wiley‐Liss, Inc.
Cortical hierarchy reflected in the organization of intrinsic connections in macaque monkey visual cortex
Authors: Amir Y. , Harel M. , Malach Rafael
Published: January 2005

Neuronal response properties vary markedly at increasing levels of the cortical hierarchy. At present it is unclear how these variations are reflected in the organization of the intrinsic cortical circuitry. Here we analyze patterns of intrinsic horizontal connections at different hierarchical levels in the visual cortex of the macaque monkey. The connections were studied in tangential sections of flattened cortices, which were injected with the anterograde tracer biocytin. We directly compared the organization of connections in four cortical areas representing four different levels in the cortical hierarchy. The areas were visual areas 1, 2, 4 and Brodman's area 7a (V1, V2, V4 and 7a, respectively). In all areas studied, injections labeled numerous horizontally coursing axons that formed dense halos around the injection sites. Further away, the fibers tended to form separate clusters. Many fibers could be traced along the way from the injection sites to the target clusters.

At progressively higher order areas, there was a striking increase in the spread of intrinsic connections: from a measured distance of 2.1 mm in area V1 to 9.0 mm in area 7a. Average interpatch distance also increased from 0.61 mm in area V1 to 1.56 mm in area 7a. In contrast, patch size changed far less at higher order areas, from an average width of 230 m̈M in area V1 to 310 m̈m in area 7a. Analysis of synaptic bouton distribution along axons revealed that average interbouton distance remained constant at 6.4 m̈m (median) in and out of the clusters and in the different cortical areas. Larger injections resulted in a marked increase in the number of labeled patches but only a minor increase in the spread of connections or in patch size.

Thus, in line with the more global computational roles proposed for the higher order visual areas, the spread of intrinsic connections is increased with the hierarchy level. On the other hand, the clustered organization of the connections is preserved at higher order areas. These clusters may reflect the existence of cortical modules having blob‐like dimensions throughout macaque monkey visual cortex. © 1993 Wiley‐Liss, Inc.
Ultrastructural analysis of sympathetic neuromuscular junctions on mesenteric veins of the guinea pig
Authors: Klemm M. F. , Van Helden D. F. , Luff S. E.
Published: January 2005

This study reports on the detailed ultrastructure of sympathetic postganglionic varicose axon terminals on mesenteric veins leading from the ileum of the guinea pig and in particular the structural arrangement of the varicosities with venous smooth muscle cells. The response to nerve stimulation in veins has a long time course and it has been suggested that this reflects a wide separation between the site of transmitter release and the receptors on the effector cell membrane. The aim of this study was to determine the distance between individual sympathetic varicosities and smooth muscle cells in mesenteric veins.

Fluorescent histochemical preparations of the sympathetic innervation of the different branches of mesenteric veins indicate the branching network of varicose axons around the vessel to be relatively dense. Electron micrographs show the innervation to be confined to the adventitia close to the medio‐adventitial border and to be predominantly catecholaminergic. A serial section ultrastructural analysis of the relationship of the varicosities with the outer smooth muscle cells showed that almost all (98%) of the exposed axon varicosities in the adventitia formed neuromuscular junctions. Three‐dimensional reconstructions from serial sections of individual varicosities have shown that the junctions have structural specialisations identical to neuromuscular junctions described on arterial vessels and similar to those found at skeletal neuromuscular junctions. The density of neuromuscular junctions on the veins was found to be similar to that on the corresponding artery in the same animal.

We suggest that in veins, noradrenaline is released focally at neuromuscular junctions. © 1993 Wiley‐Liss, Inc.
Localization of NADPH‐diaphorase in the brain of the chicken
Authors: Brüning Gerold
Published: January 2005

NADPH‐diaphorase, an enzyme catalyzed reaction thought to reflect the activity of nitric oxide synthase in the mammalian nervous system, was mapped in the brain of the chicken. Intensely stained neurons and fibers were found in most parts of the telencephalon, in particular in the neostriatum, paleostriatum augmentatum, olfactory tubercle, lobus parolfactorius, hyperstriatum accessorium, and hyperstriatum ventrale. Medial to the nucleus taeniae, an accumulation of stained cells was observed that appeared to merge with a band of stained neurons located dorsal to the occipitomesencephalic tract. These are considered to belong to the nucleus interstitialis of the dorsal olfactory projection. Further caudally, neurons with different staining intensities were found in the lateral hypothalamic area, lateral mammillary nucleus, periventricular organ, ventral tegmental area, medial spiriform nucleus, optic tectum, isthmooptic nucleus, mesencephalic trigeminal nucleus, interpeduncular nucleus, and central gray of the mesencephalon. A particularly dense cluster of NADPH‐diaphorase positive neurons was located in the locus coeruleus. It is proposed that these might represent cholinergic cells intermingled with catecholaminergic neurons, thus forming the avian counterpart of the tegmental cholinergic nuclei of mammals. Several NADPH‐diaphorase reactive neurons were seen in the parabrachial nucleus and medial and dorsal vestibular nucleus, as well as scattered in the reticular formation. In the caudal medulla, intensely stained cells were grouped around the central canal. Therefore the pattern of expression of NADPH‐diaphorase, and thus possibly of nitric oxide synthase, within the avian and mammalian brain might be largely conserved. © 1993 Wiley‐Liss, Inc.
Innervation of the monotreme gastrointestinal tract: A study of peptide and catecholamine distribution
Authors: Keast J. R.
Published: January 2005

The distribution of neurons and endocrine cells containing various peptides or catecholamines was examined in the digestive tracts of the echidna (Tachyglossus aculeatus) and the platypus (Ornithorhynchus anatinus). Comparisons were made with published studies in other species in order to obtain a broader view of the phylogenetic distribution and possible functions of gut peptides and catecholamines. Further comparisons between the echidna and platypus were made in light of their different dietary features and gut histology. The distribution of neurons and axons containing catecholamines or various peptides resembled that in other species (such as the frequent appearance of axons containing substance P and vasoactive intestinal peptide in the intestinal mucosa, and axons containing substance P or enkephalins in the circular muscle). In both species, the stomach histologically resembles the esophagus, being aglandular and lined with stratified squamous epithelium. Innervation of these two organs was similar but not identical, with a greater array of peptides found in the gastric muscle. The intestinal mucosa was densely innervated in both species. The platypus small intestine is unusual in having a thick and deeply folded mucosa (but no villi), in which the superficial epithelium is absent or incomplete at many sites; many axons travel close to these luminal surfaces. Many (putative noradrenergic) axons associated with blood vessels contained neuropeptide Y, but there was no evidence for intrinsic catecholamine‐containing neurons. Somatostatin and cholecystokinin were present in some endocrine cells, but unlike many mammals, absent in neuronal tissue. These studies have shown that there are many strong similarities between monotremes and other mammals in the distribution and array of peptides found within nervous and endocrine tissues of the digestive tract. However, numerous small differences of the echidna and platypus innervation may be correlated with their different digestive structures. © 1993 Wiley‐Liss, Inc.