bluuebunny/crossref_metadata_2025_split huggingface dataset:
The projections of principal cells of the medial nucleus of the trapezoid body in the cat
Authors: Spangler Kevin M. , Warr W. Bruce , Henkel Craig K. 
Published: May 2005

AbstractPrevious studies suggest that the principal cells of the medial nucleus of the trapezoid body (MNTB) give rise to the projection from MNTB to the lateral superior olivary nucleus (LSO) of the same side, where they mediate rapid inhibitory effects of contralateral sound stimulation. In the present study, we explored certain morphological features of this connection as well as several other projections of the MNTB by using anterograde and retrograde axonal tracing methods. Following injections of tritiated leucine into MNTB, labeled axons reached LSO by passing ventral to, dorsal to, and through the medial superior olivary nucleus, and gave rise to labeling around the somata and proximal dendrites of LSO fusiform cells. As measured in autoradiograms of 2 μm plastic sections, these axons had a modal diameter of 5–6 μ. Terminal labeling, tentatively attributed to principal cell axons, was also seen in the ventral nucleus of the lateral lemniscus (VNLL) and the dorsomedial and ventromedial periolivary nuclei. HRP injections into the LSO and the VNLL showed that the prinicpal cell projected to both of these nuclei and revealed a topographic arrangement of the projection to the LSO which is consistent with tonotopic maps determined electrophysiologically. Control HRP injections demonstrated that other minor projections of the MNTB arose from minor cell populations in this nucleus. The findings provide a morphological correlate of certain physiological findings and suggest a wider role for the MNTB in the ascending auditory system than previously has been supposed.
The neuronal composition of area 17 of rat visual cortex. III. Numerical considerations
Authors: Peters Alan , Kara Daniel A. , Harriman Katherine M. 
Published: May 2005

AbstractThe neuronal population of area 17 of rat visual cortex has been examined by using tissue from brains fixed by perfusion. The tissue was osmicated and embedded in plastic so that the same neurons could be examined by both light and electron microscopy. In these preparations area 17 was 1.49 mm thick and by stereological procedures it was calculated that there are about 120,000 neurons beneath 1 mm2 of cortical surface. If one assumes area 17 in each hemisphere of the rat to occupy between 7.1 and 9.4 mm2 of cortical surface, then in each hemisphere the area contains between 850,000 and 1,128,000 neurons. Of these neurons 85% are pyramidal cells and 15% are nonpyramidal cells. About one‐third of the nonpyramidal cells occur in layers I and VIb, both of which contain only this kind of neuron. The remaining two‐thirds of the nonpyramidal cells are in layers II‐VIa. Within these layers it has been possible to differentiate bipolar cells from other types of nonpyramidal cells and in each of these two nonpyramidal cell groups to recognize both small and large neurons. The greatest concentration of nonpyramidal cells occurs in layer II/III. To confirm the validity of the stereologically derived data direct counts were made of the medium and large pyramidal cells in layer V.
Dendrite distribution of identified motoneurons in the lumbar spinal cord of the turtlePseudemys scripta elegans
Authors: Ruigrok T. J. H. , Crowe A. , ten Donkelaar H. J. 
Published: May 2005

AbstractMotoneurons in the turtle lumbar spinal cord were injected with HRP by electrophoresis after being electrophysiologically identified as innervating a muscle belonging to a functional group. The distribution of dendrites was studied in transverse reconstructions of 45 motoneurons, including motoneurons identified as innervating knee extensor muscles, eight motoneurons innervating hip retractor and knee flexor muscles, 14 motoneurons innervating ankle and/or toe extensors and 12 motoneurons innervating ankle and/or toe flexor muscles.The dorsal dendritic tree of motoneurons innervating distally positioned musculature (ankle and/or toe extensors and flexors) was observed to contain significantly less terminal dendritic branches compared to the dorsal dendritic trees of motoneurons innervating proximally situated (hip and knee) muscles.The distribution of dendrites within the white matter was studied by measuring the total projected length of the dendritic branches within empirically defined sectors in the transverse plane. This kind of analysis also revealed differences between the dorsal dendrites of motoneurons innervating distally and proximally positioned muscles conforming to the counts of terminal dendritic branches. It is suggested that these apparent differences in the size of the dorsal dendrite may be related to the number of synapses made by primary afferents.In the white matter, the highest dendritic density for all four groups of mononeurons was found within the central part of the lateral funiculus. However, only in the ventral funiculus could slight indications be found that the dendritic density of functionally different motoneuron groups may bear some relation to the locations of the terminations of the descending pathways known to establish monosynaptic contacts with lumbar mononeurons.
Unmyelinated primary afferent fibers in dorsal funiculi of cat sacral spinal cord
Authors: Chung Kyungsoon , Coggeshall Richard E. 
Published: May 2005

AbstractThe present study tests the hypothesis that there are numerous unmyelinated primary afferent fibers in cat posterior funiculi. The animals have unilateral dorsal rhizotomies from L6 to Ca3. One week later the axons of both S2 dorsal funiculi are counted. The data indicate that there are approximately 22,500 myelinated and 8,500 unmyelinated axons on the unoperated side and 11,000 myelinated and 3,900 unmyelinated axons on the operated side. On this basis we suggest that 51% of the myelinated and 54% of the unmyelinated axons in cat dorsal funiculi arise from dorsal root ganglion cells and thus are primary afferent axons. If this is correct, then 71% of the primary afferent axons in the cat dorsal funiculus are myelinated and 29% are unmyelinated. The function of this large group of previously unsuspected fine sensory axons remains to be determined.
I. Cytology and distribution in normal human cerebral cortex of neurons immunoreactive with antisera against neuropeptide Y
Authors: Chan‐Palay V. , Allen Y. S. , Lang W. , Haesler U. , Polak J. M. 
Published: May 2005

AbstractThe frontal, parietal, and temporal cortices in normal human brains (Brodmann areas 10, 7a, 7b, and 21) are well endowed with numerous neurons, identifiable by immunoreactivity with antisera against the 36‐amino acid brain peptide neuropeptide Y (NPY). These neurons with rare exception are small, intracortical, nonspiny neurons, 12–20 μm in somatic size, with long slender dendrites and exuberant axon plexuses exhibiting finely beaded varicosities. The cells are rarest in layers I and II, are found with frequency in the lower cortical layers (IV‐VI) and in significant numbers in the subcortical white matter. Within the cortex the axonal plexuses of these peptide neurons rise straight up into the upper cortical layers or descend deep into the white matter. In layers I and II, numerous other lengthy axons, some possibly of extracortical afferent origin, run along the pial surface at right angles to the axial ones running perpendicular to the cortex. This endowment of peptide neurons and their processes forms a rich network in the cerebral cortex, relating with one another in complex fashion within palisades of terminals as well as with the other cortical neurons not labeled by these methods. It remains to be shown what functions these NPY neurons have individually and in their remarkable networks, and how they are altered in neurological disease.
Long ascending projections to the midbrain from cells of lamina I and nucleus of the dorsolateral funiculus of the rat spinal cord
Authors: Swett John E. , McMahon Stephen B. , Wall Patrick D. 
Published: May 2005

AbstractSmall volumes (5–40 nl) of an aqueous solution of wheat‐germ‐agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) were injected unilaterally into midbrain structures of 18 adult, albino rats. In 17 of these preparations cells of many types were found to be retrogradely labeled in cervical and lumbar spinal cord segments. The data reported here concern the number and location of labeled cells from injection sites in the midbrain that affected two distinct cell populations: neurons within the marginal layer (lamina I cells) and neurons of the nucleus of the dorsolateral funiculus (NDLF cells). In ten of the preparations, only nine of which are reported in detail here, a total of 1,831 labeled lamina I cells were identified. In the lumbar enlargement they reached a density of more than 60 cells/mm. Of these, 85% projected to medial portions of the caudal, contralateral midbrain. Injection sites that were centered in the caudal periaqueductal gray (PAG) and/or in the immediately adjacent region of nucleus cuneiformis labeled the largest numbers of lamina I cells. Cells of the NDLF were retrogradely labeled in all preparations in which lamina I cells were labeled but they were also observed in five cases in which lamina I cells were not labeled. A total of 1,914 NDLF cells were labeled from all injection sites. These cells were found to have essentially a bilateral distribution with 57% of the cells located in the contralateral DLF. Although there is substantial overlap between the terminal fields of lamina I and NDLF cells within the midbrain, NDLF cells had a more diffuse target area encompassing the reticular core of the midbrain and PAG, bilaterally, while the target area for lamina I cells was comparatively discrete, being largely restricted to the more medially situated midbrain structures, contralaterally. Whether the terminations of lamina I cells in and near the PAG are from collaterals of spinothalamic neurons originating in lamina I, or a subclass of lamina I neurons that project exclusively to the midbrain, is not known. It is significant, however, that lamina I cells, known to be activated by noxious stimuli to the skin, should project to a region of the brain stem from which analgesia can be produced by electrical stimulation or by local application of opiates.
A correlation between receptive field properties and morphological structures in the pretectum of the cat
Authors: Ballas I. , Hoffmann K. P. 
Published: May 2005

Abstract
Retinal terminals in the pretectum were labelled by anterograde axonal transport of horseradish peroxidase (HRP) after injecting the enzyme into one eye.
Pretectal neurons were retrogradely labelled by HRP‐injections into the dorsal cap of the inferior olive.
Electrophysiological recordings were performed in the same animal. This procedure showed that direction‐selective neurons in the nucleus of the optic tract (NOT) projecting to the dorsal cap of the inferior olive lie dorsal and lateral to the retinal terminal clusters. Direction‐unselective neurons sensitive to high stimulus velocities (jerk‐neurons) were localized within the areas of retinal terminal clusters. Both jerk‐neurons and retinal terminal clusters never overlapped with retrogradely labelled neurons.
Latency measurements to stimulation of the optic chiasm (OX) confirmed a monosynaptic W‐cell projection to the direction‐selective NOT cells and indicated a predominantly monosynaptic Y‐cell projection to the jerk‐neurons.
Organization and postnatal development of callosal connections in the visual cortex of the rat
Authors: Olavarria Jaime , van Sluyters Richard C. 
Published: May 2005

AbstractThe distribution of callosal cells and terminals was studied in the posterior neocortex of pups whose ages ranged from 3 to 16 days and in adult rats 2 months of age or older. Callosal cells and terminations were revealed using retrograde (horseradish peroxidase) and anterograde (horseradish peroxidase; tritiated proline) tracing techniques, respectively, and the distribution of callosal connections was analyzed in tangential or coronal histological sections.In agreement with previous studies, we observed that the pattern of callosal connections in areas 17 and 18 of adult rats contains the following features: (1) a dense band of callosal cells and terminations separating the interiors of areas 17 and 18a, (2) a ringlike configuration anterolateral to area 17, (3) a region of dense labeling lateral to area 18a, (4) several narrow bands of labeling that bridge area 18a at different anteroposterior levels, and (5) one or more labeled regions in area 18b. In all these callosal regions, labeled cells and terminations are densely aggregated in layers II–III, Va, and Vc–VIa, and less densely in layer IV and the remaining portions of layers V and VI. High densities of isotope‐labeled fibers are also observed in the lower half of layer I. Throughout the interiors of areas 17 and 18a, a significant number of labeled cells are observed in layers Vc–VIa.In contrast to adult rats, in neonates no distinct tangential pattern of callosal connections is apparent. Instead, labeled cells are densely aggregated in two continuous horizontal bands located in cortical layers Va and Vc–VIa, and callosal axons are largely restricted to white matter. During the first 2 postnatal weeks there is a progressive loss of callosal cells in regions that normally have few callosal cells in the adult (e.g., interiors of areas 17 and 18a) and an increase in the number of cells in layers II–IV in regions that are densely callosal in the adult (e.g., callosal regions at the 17/18a border, lateral border of area 18a, and in area 18b). The decrease in the number of callosal cells in the interiors of areas 17 and 18a is more severe in the upper than in the lower band of the immature labeling pattern, and our data from tangential sections indicate that this loss of callosal neurons occurs synchronously across the interiors of these areas. During this period there is also a localized invasion of labeled callosal axons into those regions of gray matter where they will be found in adult life. By 7 days of age, all major features of the mature callosal pattern can be clearly recognized, and by 12 days of age—a few days before eye opening—the pattern appears virtually mature.
A correlated light and electron microscopic study of identified cholinergic basal forebrain neurons that project to the cortex in the rat
Authors: Ingham C. A. , Bolam J. P. , Wainer B. H. , Smith A. D. 
Published: May 2005

AbstractCholinergic neurons in the basal forebrain which project to the frontal cortex were studied by combining the retrograde transport of a conjugate of horseradish peroxidase and wheat germ agglutinin with choline acetyltransferase immunohistochemistry. Neurons that were both retrogradely labelled and immunoreactive were found on the medial, lateral, and ventral borders of the globus pallidus, within the globus pallidus, as well as in the substantia innominata and ventral pallidum region.The cell bodies averaged 31 by 19 μm in size and had sparsely branching dendrites. Cells which were labelled by both techniques were first characterised in the light microscope and then studied in the electron microscope. The perikarya had large amounts of cytoplasm with abundant organelles. The nuclei were indented, were usually eccentrically placed, and contained prominent nucleoli. The synaptic input onto the cell bodies and their dendrites was studied in serial sections. The synaptic input onto the perikarya and proximal dendrites was sparse but the density increased on more distal regions of the dendrites. Subjunctional bodies were associated with the postsynaptic membrane in 20–30% of the synaptic contacts and these were classified as asymmetrical; the remaining contacts could not be classified because of an association of the immunoreaction product with the postsynaptic membrane. The synaptic input to these cells was distinctly different from that onto typical globus pallidus cells, the perikarya and dendrites of which were characteristically ensheathed in synaptic boutons.
Dendritic arbors and dendritic excrescences of abnormally positioned neurons in area CA3c of mice carrying the mutation “Hippocampal lamination defect”
Authors: Nowakowskl R. S. , Davis T. L. 
Published: May 2005

AbstractBALB/cJ and BALB/cByJ mice are homozygous for the autosomal gene “hippocampal lamination defect” (provisional gene symbol: Hld) which produces an abnormality in the lamination of the pyramidal cell layer of area CA3c of the hippocampus such that early‐generated neurons are superficial and late‐generated neurons are deep. Other inbred strains of mice are wild‐type (+/+) at the Hld locus and do not have this inversion in cell position in area CA3c. The Golgi method was used to analyze the dendritic arbors of the abnormally positioned pyramidal cells and to compare the distribution of dendritic excrescences (i.e., the termination sites of the mossy fibers) in +/+ and Hld/Hld mice. It was found that in +/+ mice the late‐generated pyramidal cells (whose cell bodies are positioned just below the suprapyramidal mossy fiber layer) have one set of dendritic excrescences on their apical dendrites as they extend through the suprapyramidal mossy fiber layer and a second set on their basal dendrites as they pass through the infrapyramidal mossy fiber layer. In contrast, in Hld/Hld mice the late‐generated pyramidal cells (whose cell bodies are abnormally positioned just below the intrapyramidal mossy fiber layer) have two sets of dendritic excrescences on their apical dendrites, as they pass through the intrapyramidal and suprapyramidal mossy fiber layers, and none on their basal dendrites. In addition, in the vicinity of the apparent point of contact of the intrapyramidal mossy fibers, the apical dendrites of some of the abnormally positioned pyramidal cells have several fine‐caliber branches. These data indicate that (1) the apical dendrites of hippocampal pyramidal cells can form normally even though the cells never reach their normal position and (2) the dendritic excrescences are induced by contact from the mossy fibers. The anatomical differences produced by the Hld/Hld genotype provide some interesting clues as to the relationship between defects in neuronal migration and the subsequent establishment of axonal connections and could be the basis for some of the behavioral differences reported to exist between BALB/cJ and other inbred strains of mice.
The morphology and ultrastructure of common inhibitory motor neurones in the thorax of the locust
Authors: Watson A. H. D. , Burrows M. , Hale J. P. 
Published: May 2005

AbstractThe morphologies of three common inhibitory motor neurones which innervate muscles of a hind leg and the homologous three neurones which innervate muscles in a middle leg are described in relation to known commissures, tracts, and areas of neuropile in their ganglia. The neurones were stained individually by the intracellular injection of cobalt, and the ultra‐structure of common inhibitor 1 (CI1) in the metathoracic ganglion was revealed by the intracellular injection of herseradish peroxidase. Homologous inhibitory motor neurones in the meso% and metathoracic ganglia have similar shapes. CI1 has axons in nerves 3, 4, and 5, but common inhibitors 2 and 3 (CI2, CI3) have only a single axon in nerve 5. They nevertheless all share many features in common. All have large (60 70 μm diameter) cell bodies in the ventral cortex near the midline, well separated from those of the excitatory leg motor neurones. Their primary neurites run dorsally and laterally and send many fine branches into the dorsal and lateral neuropile, and some fine branches medially. None enter the ventral neuropile. CI1 and CI2 have a small branch that arises close to the cell body and arborises on either side of the midline. When examined with the electron microscope, CI1 was not found to make any output synapses, even though some of its fine branches are varicose and end in bulbous swellings. These were seen to be packed with mitochondria but not vesicles. Input synapses tend to be grouped together on the secondary neurites and, more especially, on the finer branches and their spines. The majority of processes presynaptic to CI1 contain round agranular vesicles.
Stimulation of photoreceptor disc shedding and pigment epithelial phagocytosis by glutamate, aspartate, and other amino acids
Authors: Greenberger Lee M. , Besharse Joseph C. 
Published: May 2005

AbstractIt has been reported that aspartate and glutamate selectively impair the structure (Olney, '82) and function (e.g., Furakawa and Hanawa, '55) of second‐ and third‐order retinal neurons while leaving the photoreceptor unaffected. Either amino acid may mimic the endogenous photoreceptor neurotransmitter (Ehinger, '82). We report here that excitatory amino acids also induce massive rod photoreceptor disc shedding in eyecups of Xenopus laevis maintanined in vitro. Disc shedding is the process whereby photoreceptors eliminate effete discs. It involves interaction between the distal outer segment and pigment epithelium. Millimolar L‐asparate and L‐glutamate, as well as micromolar kainic acid, a glutamate analog, stimulate disc shedding three‐to fivefold higher than normal light‐evoked shedding levels and result in extensive inner retinal damage. Fifty‐millimolar KC1, 1.0 μM ouabain, and replacement of sodium with choline also stimulate disc shedding and alter retinal structure. Extensive neurotoxicity appears unrelated to disc shedding since other amino acids having no significant or marginal effects on retinal structure also stimulate shedding. While the site and mechanism of action of these effectors, and in particular the excitatory amino acids, is now undefined, the data show that amino acids thought to act directly and specifically on inner retinal neurons can also markedly alter photoreceptor and pigment epithelial metabolism.
Organization of the filum terminale in the frog
Authors: Chesler Mitchell , Nicholson Charles 
Published: May 2005

AbstractThe histological organization of the filum terminale of the spinal cord in Rana catesbeiana and Rana pipiens was characterized to determine if this region possessed an organized neuropil or whether it was merely a glial remnant that persisted after absorption of the larval tail.The excised filum was maintained in vitro. Intracellular electrophysiological recording was performed with horseradish peroxidase injection. Tyrosine hydroxylase and serotonin distribution were revealed by immunocytochemical methods.Astroglia were the dominant cell type and displayed an elaborate variety of forms. The mean membrane potential was logarithmically related to the extracellular potassium concentration but displayed a sub‐Nernstian slope. Oligodendroglia were also seen, as well as ependyma that extended from the central canal to the pial surface.Neuronal activity was revealed by occasional intracellular penetration of elements that displayed spontaneous excitatory postsynaptic or action potentials. The major evidence for the presence of neurons was the demonstration of tyrosine hydroxylase (TH) immunoreactivity in a large population of cerebrospinal fluid‐contacting neurons that abutted the ventral half of the central canal. The axons of these cells entered a ventral bundle and ascended the cord; some fibers left this tract and apparently terminated on large arcuate neurons within the filum. Serotoninergic fibers were primarily confined to a subpial location at the dorsal midline.We conclude that the filum terminale of the frog has a sparse but functional neuropil that is organized around the central canal and supported by a profusion of elaborate glial forms.