bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological variability, segmental relationships, and functional role of a class of commissural interneurons in the spinal cord of goldfish
Authors: Fetcho Joseph R. 
Published: January 2005

AbstractAs part of an attempt to understand the spinal control of the segmented axial musculature in goldfish, commissural spinal interneurons that are electrotonically coupled to the Mauthner axon (M‐axon) were studied with intracellular recording and staining to examine their morphology, segmental relationships, and functional role. Prior studies suggested that these cells might mediate the crossed inhibition that blocks excitation of motoneurons on one side of the body during an escape bend to the opposite side. Simultaneous intracellular recordings from a M‐axon, a commissural interneuron coupled to it, and a presumed primary motoneuron show that: (1) the interneurons produce monosynaptic, CI−‐dependent IPSPs in contralateral motoneurons, (2) the interneurons are responsible for the short latency, crossed spinal inhibition in the M‐cell network, and (3) more than one interneuron terminates on each postsynaptic cell. Reconstructions of interneurons from wholemounts show that they form a fairly homogeneous morphological class of cells. Each one is unipolar, with an axon that crosses the cord and then usually bifurcates into a short, thin ascending branch and a thicker, longer descending one. Neighboring interneurons have overlapping terminal arbors consistent with the physiological data showing convergence of interneurons onto the same postsynaptic cell. The interneurons showed little relationship with body segments as denned by ventral roots. Their axons usually straddled segmental boundaries, with terminals typically occupying parts of two adjacent segments. Thus the functional unit of these cells is probably not a segment or a complete group of segments, but instead includes only parts of two adjacent segments. The presence of interneurons like these suggests that the overt peripheral segmentation of trunk musculature is not necessarily reflected in the organization of neurons that control those segments. A consideration of some functional characteristics of the activation of overlapping, serially repeated arrays of interneurons by descending pathways leads to the conclusion that the high conduction velocity of the M‐axon, and the large size and short longitudinal extent of the axons of the inhibitory interneurons promote a strong, brief inhibition that is appropriate for the production of an escape turn that has a rapid bend to one side.
Ultrastructure of the electrotonic and chemical components of the lateral‐to‐motor and medial‐to‐motor synapses in crayfish nerve cord
Authors: Bosch Elizabeth 
Published: January 2005

AbstractLateral‐to‐motor and medial‐to‐motor synapses in crayfish nerve cords are composed of an electrical and a chemical component. The presynaptic terminals showed localized clusters of synaptic vesicles, electron‐dense areas, coated pits, and coated vesicles. In thin sections, active zones were defined by electron‐dense regions where synaptic vesicles attached and, in freeze‐fracture replicas, by clusters of intramembrane particles localized in bands with vesicle openings on the sides of these bands.The cytoplasmic surface of the postsynaptic membrane opposite the active zones was coated with electron‐dense material that in freeze‐fracture replicas was seen as an increase in intramembrane particles located in the external leaflet (EF‐face). This specialization of the postsynaptic membrane may correspond to the neurochemical receptor. Also, pre‐ and postsynaptic membranes were separated by a wider extracellular gap than those of adjacent nonsynaptic regions and electrical synapses or gap junctions.Synaptic vesicles were located exclusively at the synaptic regions by means of a cytoskeleton that was different for the electrical and the chemical components. The vesicles associated with the electrical component were anchored to a cytoskeleton composed of a beaded layer of densities located parallel to the membrane. This cytoskeleton maintained the synaptic vesicles separated from the presynaptic membrane by a distance of 13 ± 2 nm. The synaptic vesicles associated with the chemical component were anchored to electron‐dense regions formed by filaments arranged in bundles, anchored to the presynaptic membrane. Vesicles lined both sides of the bundle of filaments in very close proximity to the presynaptic membrane, probably positioned to discharge their contents into the extracellular space and to replace the discharged vesicles.
Cochlear innervation in the developing rat: An immunocytochemical study of neurofilament and spectrin proteins
Authors: Hafidi A. , Despres G. , Romand R. 
Published: January 2005

AbstractWe have studied the innervation of the developing cochlea by immunocytochemical staining of the cytoskeletal proteins, neurofilament (NF), and spectrin (brain spectrin and erythrocyte spectrin). NF immunoreactivity was seen in spiral ganglion cell bodies and their processes and in fibers of the intraganglionic spiral bundle (IGSB) on gestational day 16. NF immunoreactivity with monoclonal antibodies to NF160 and NF68 was present beneath both inner hair cells (the IHC) and outer hair cells (OHCs) on gestational day 20. NF200 immunostaining was located only in the IGSB and in fibers reaching the IHC, The first NF200 immunoreactivity beneath the OHCs was seen in the basal turn at birth, NF labelling began to decrease on postnatal day 9 and its intensity became more like that of the adult. Brain spectrin immunostaining was first seen in the IGSB of the basal turn on gestational day 18. It reached the fibers between the spiral ganglion and the IHC on gestational day 20. Brain spectrin immunoreactivity was first seen beneath the OHCs in the basal turn at birth. It reached all the OHCs of the cochlea by postnatal day 4, and began to decrease 9 days after birth. Erythrocyte spectrin immunostaining was first observed during the second postnatal week, when it labelled spiral ganglion cells. The distribution of NF200 and brain spectrin immunoreactivity suggested that efferent innervation of OHCs is present at birth in the rat, and confirms previous studies showing the early efferent innervation of the OHCs of the mouse and the rat at birth, and the time lag between the appearance of the two spectrin isoforms during development.
Synaptic connections of neuropeptide Y (NPY) immunoreactive neurons in the hilar area of the rat hippocampus
Authors: Deller Thomas , Leranth Csaba 
Published: January 2005

AbstractSynaptic connections and fine structural characteristics of neuropeptide Y‐immunoreactive (NPY‐i) neurons in the fascia dentata were studied using an antiserum against NPY. Normal and colchicine pretreated rats were examined to study the synaptic connections of NPY‐i neurons in the normal fascia dentata. The perforant pathway and fimbria fornix were transected to label afferent fibers to NPY‐positive cells. Horseradish peroxidase conjugated with wheat germ agglutinin (HRP‐WGA) was injected into the contralateral hippocampus to study commissural projections of hippocampal NPY‐i neurons, and to search for NPY‐i synaptic contacts on immunonegative commissural cells. Since earlier reports have shown that at least half of the NPY‐i neurons also contain somatostatin (SS), the distribution of NPY‐i neurons in the hilar area was determined and compared with that of SS‐i neurons. Four types of dentate NPY‐i neurons were distinguished: Type 1: large multipolar cells in the deep hilus (9%). Type 2: medium‐sized multipolar and fusiform hilar neurons with dendrites occasionally reaching the outer molecular layer (64%). Type 3: pyramidal shaped cells in the granule cell layer with long apical dendrites reaching the outer molecular layer (20%), Type 4: small multipolar NPY‐i cells located in the molecular layer (7%). Our results indicate two overlapping but not identical cell populations of NPY‐i and SS‐i neurons. Light and electron microscopic analysis of the normal fascia dentata demonstrated that the majority of NPY‐i terminals are located in the outer molecular layer of the dentate gyrus, where they establish symmetric synaptic contacts on dendritic shafts and occasionally on spines of granule cells. A moderate number of NPY‐i synapses were also found on dendrites in the inner molecular layer and on the cell body of granule cells. Numerous symmetric NPY‐i synapses were found on dendrites and somata of neurons in the hilar area. Some NPY‐i dendrites in the hilar area received mossy axon collateral input. After transection of the perforant pathway degenerated axon terminals could be found in synaptic contact with NPY‐i dendrites in the outer molecular layer. Commissurotomy revealed direct commissural input to NPY‐i dendrites in the inner molecular layer and in the hilus. After injection of HRP‐WGA into the contralateral hippocampus 2% of hilar NPY‐i neurons were retrogradely labeled and symmetric NPY‐i synapses were found on the cell bodies and dendrites of unstained HRP‐WGA labeled neurons. This study suggests that NPY‐i neurons receive entorhinal and commissural afferents and in turn form contacts with granule cells and commissural neurons in the fascia dentata. Some NPY‐i neurons may be the targets of perforant pathway afferents as well as mossy axon collaterals which may explain their vulnerability to hippocampal seizure activity.
Collaterals from lateral and medial olivocochhlear efferent neurons innervate different regions of the cochlear nucleus and adjacent brainstem
Authors: Ryan Allen F. , Keithley Elizabeth M. , Wang Zhi‐Xian , Schwartz Ilsa R. 
Published: January 2005

AbstractTwo populations of superior olivary neurons which project to different sensory cell regions in the cochlea also give off collateral projections to the ventral cochlear nucleus (VCN) and adjacent brainstem. To determine whether these VCN projections also have different targets, they were characterized by selective retrograde amino acid transport. Retrograde transport of 3H‐d‐aspartate (D‐ASP) selectively labeled the unmyelinated fibers and neurons of the lateral olivocochlear (OC) system, including a dense collateral projection to the central VCN. Retrograde transport of 3H‐nipecotic acid (NIP) labeled the myelinated fibers and neurons of the medial OC system, including collateral projections to the peripheral VCN, subpeduncular granule cells, and nucleus Y. Medial and lateral OC efferent collaterals thus innervate different regions of the CN. Lateral system collaterals overlap extensively with Type I spiral ganglion cell afferent input. They are well positioned to play a role in modulating afferent input to the central auditory system, as is the primary projection of these efferents to the cochlea. The medial system collaterals project near the recently described afferent projections of Type I1 spiral ganglion cells. The medial system collaterals may therefore be related to the function of outer hair cells, as the medial system primary axons appear to be in the cochlea.
Effects of visual or light deprivation on the morphology, and the elimination of the transient features during development, of type I retinal ganglion cells in hamsters
Authors: Lau Kam Chetjng , So Wok‐Fai , Tay David 
Published: January 2005

AbstractIntracellular injection of Lucifer Yellow (LY) was used to study the detailed morphology of the normal, visually deprived, and light‐deprived superior colliculus projecting Type I retinal ganglion cells (RGCs) in hamsters. The soma size of the normal Type I cells ranged from 337 to 583 pm2 with a mean of 436 pm2. Two to six primary dendrites were observed in these cells. The mean dendritic field diameter was 495 km and ranged from 309 to 702 pm. The dendritic field diameter of this population of cells exhibited an eccentricity dependence. Quantitative comparisons between the normal and visually deprived or light‐deprived Type I RGCs indicated that the morphology of these three groups of cells were similar to each other in terms of the soma size, dendritic field diameter, branching pattern, and total length of the dendrites.During the normal development of cats and hamsters, several transient features, such as exuberant dendritic spines and intraretinal axonal branches, have been observed in the developing RGCs. The complete elimination of these transient features occurs at about 3 and 2 weeks after the opening of the eyes in cats and hamsters, respectively. In the present study, the hypothesis whether visual experience or light stimulation is required for the elimination of these transient features during development was examined. After studying a total of 115 mature Type I RGCs, which included cells from the normal, visually deprived, and light deprived animals, no transient feature was observed.We conclude that visual or light deprivation has no effect on the morphological develop‐ ment of superior colliculus projecting Type I RGCs in hamsters, and the elimination of the transient features on the Type I RGCs during development does not depend on visual experience or light stimulation.
A vasopressin and oxytocin containing nucleus in the pig hypothalamus that shows neuronal changes during puberty
Authors: van Eerdenburg Frank J. C. M. , Poot Peter , Molenaar Gerard J. , van Leeuwen Fred W. , Swaab Dick F. 
Published: January 2005

AbstractA vasopressin and oxytocin containing nucleus is described for the first time in the pig hypothalamus. It is located near the third ventricle, just dorsal to the suprachiasmatic nucleus, and consists of magnocellular neurons, similar to those of the supraoptic nucleus and paraventricular nucleus. Morphometric analysis of neuronal number, size, density, and volume was performed at four different ages: 1 day, 7 weeks, 16 weeks, and 30 weeks postnatally. No sex difference in these parameters was observed. In this period the volume of the nucleus increased gradually from 6.6 X 10−3 to 54.2 X 10−3 mm3. One day after birth 1,215 ± 191 (mean ± SEM) neurons were present in the vasopressin and oxytocin containing nucleus, followed by a decrease to 771 ± 80 neurons at 7 weeks and 697 ± 116 at 16 weeks. Between 16 and 30 weeks (puberty) there was a dramatic increase in neuron number up to 1,765 ± 214 neurons. This increase in the number of vasopressin and oxytocin containing neurons in the pig hypothalamus is much later in development than has ever been reported so far.
The anterior ectosylvian sulcal auditory field in the cat: I. An electrophysiological study of its relationship to surrounding auditory cortical fields
Authors: Clarey Janine C. , Irvine Dexter R. F. 
Published: January 2005

AbstractThe extent of a region containing acoustically responsive neurons within the anterior ectosylvian sulcus and its relationship to surrounding gyral auditory cortical fields was examined in chloralose‐anaesthetized cats. Multiple microelectrode penetrations were made orthogonal to the middle and anterior ectosylvian gyral surfaces, and longer penetrations were made into the dorsal and ventral banks and fundus of the anterior ectosylvian sulcus. The quantitative and qualitative auditory response characteristics of neurons and neuron clusters in the sulcal banks and surrounding regions were mapped in detail, and the degree of overlap of auditory and visual neurons within the sulcus was determined by routinely testing for responsiveness to a gross light flash.The detailed results from three animals and a summary of all penetrations into the sulcus are presented. The anterior ectosylvian sulcal field (Field AES) lay deep within the banks and fundus of the posterior three quarters of the sulcus. A combination of changes in the auditory response characteristics of neurons (i.e., in optimal stimulus, latency, and frequency tuning), and the presence of visually responsive cells, distinguished this field from surrounding fields. The distinction between the anterior ectosylvian field and extensions of the nearby tonotopic fields (i.e., primary and anterior auditory fields) into the dorsal and ventral banks of the dorsoposterior sector of the sulcus was readily made on the basis of these characteristics. The distinction between the anterior ectosylvian field and extensions of the second auditory field into the ventral bank of the middle sector of the sulcus was more difficult and there were differences between animals in the transition between these fields. Anterior ectosylvian sulcal field responses did not extend into the dorsal bank in anterior parts of the sulcus but were restricted to fundal regions, an observation consistent with the presence of the fourth somatosensory field in the dorsal bank of this sector of the sulcus. The majority of penetrations into the sulcus revealed coextensive auditory and visual activity, an observation apparently at variance with the identification of a purely visual field in this region. Barbiturate anaesthesia, which has been used in experiments demonstrating an anterior ectosylvian visual area, was found to have a depressing effect on auditory responses within the anterior ectosylvian sulcal field.
The dopaminergic amacrine cell
Authors: Dacey Dennis M. 
Published: January 2005

AbstractThe detailed morphology of the dopaminergic amacrine cell type has been characterized in the macaque monkey retina by intracellular injection of horseradish peroxidase (HRP). This cell type was recognized by its large soma in an in vitro, wholemount preparation of the retina stained with the fluorescent dye, acridine orange. HRP‐fills revealed a large, sparsely branching, spiny dendritic tree and a number of extremely thin, axon‐like processes that arose from the soma and proximal dendrites. The axon‐like processes were studded with distinct varicosities and were traced for up to 3 mm beyond the dendritic tree. The true lengths of the axon‐like processes were greater than 3 mm, however, because the HRP reaction product consistently diminished before an endpoint was reached. Both the dendrites and the axon‐like processes were narrowly stratified close to the outer border of the inner plexiform layer, although in a few cases single axon‐like processes projected into the outer nuclear and outer plexiform layers.The HRP‐filled amacrines appeared equivalent to a subpopulation of neurons that are intensely immunoreactive for tyrosine hydroxylase (TH). TH‐immunoreactive cells showed a nearly identical soma size and dendritic field size range, the same pattern of dendritic branching and spiny morphology, and also gave rise to distinct axon‐like processes from both the soma and proximal dendrites.To test this correspondence more directly, the large acridine stained cells were injected with Lucifer Yellow and the retina was subsequently processed for TH immunoreactivity using diaminobenzidine as the chromagen. In all cases Lucifer Yellow injected cells also showed intense TH immunoreactivity.Spatial densities of the TH amacrine cells were therefore used to calculate coverage factors for the dendritic trees and for the axon‐like components of the HRP‐filled cells. The axon‐like processes showed a coverage factor of at least 300, about 100 times that of the dendritic fields. This great overlap could be directly observed in TH‐immunoreacted retinal wholemounts as a dense plexus of fine, varicose processes. The density of the TH plexus is greater than the density predicted from the lengths (1–3 mm) of the HRP‐filled axon‐like processes however, and suggests that the axon‐like processes have an actual length of about 4–5 mm.The dual morphology of the dopaminergic amacrine, coupled with the previous studies of identified dopaminergic synapses, suggests the hypothesis that the varicosities on the axon‐like processes are the major source of synaptic output, and that the spiny dendrites are the major recipients of synaptic input from cone bipolar cells and other amacrine cells.The rare extension of the axon‐like processes into the outer plexiform layer, and current understanding of the morphology of dopaminergic interplexiform cells in teleost fish, supports the hypothesis that the dopaminergic amacrine and interplexiform cells represent a single cell type in which there is quantitative variation across species in the projection pattern of the axon‐like processes.
Molecular identification of the lugaro cell in the cat cerebellar cortex
Authors: Sahin Mustafa , Hockfield Susan 
Published: January 2005

AbstractThe cerebellar cortex contains five major classes of neurons that can be differentiated from one another on the basis of their location, size, shape, and, in some cases, molecular characteristics. The cerebellar cortex also contains other, less numerous neuronal types, including the Lugaro cell, which has been described on only a few occasions. The Lugaro cell is a relative rare cell type and is characterized by a fusiform cell body with thick, horizontally oriented dendrites. It is located in or slightly below the Purkinje cell layer. Because the Lugaro cell shares some morphological characteristics with the other large granular layer neurons, it often has been classified as a Golgi cell.In the present study we have taken advantage of differences in the molecular properties of neurons and have used monoclonal antibodies to identify and classify the Lugaro cell. Three large neuronal types in the cerebellar cortex were examined with cell‐type‐specific antibodies: Cat‐301 and Cat‐304 for Lugaro cells; Rat‐303 for Golgi cells; and anti‐calbindin for Purkinje cells. Double label immunocytochemistry on sections of the cat cerebellum was performed with subclass‐ or species‐specific secondary antibodies. Each of the three antibodies was selective for one of the three large neuron classes. Cat‐301 and Cat‐304 recognized Lugaro cells but not Golgi or Purkinje cells.Our results demonstrate that the Lugaro cells are molecularly, as well as morphologically, distinct from Purkinje and Golgi cells and thus constitute a distinct cell type in the cerebellar cortex.
An intracellular study of respiratory neurons in the rostral ventrolateral medulla of the rat and their relationship to catecholamine‐containing neurons
Authors: Pilowsky Paul M. , Jiang Chun , Lipski Janusz 
Published: January 2005

AbstractIntracellular recording and labelling with Lucifer yellow of respiratory neurons in the rostral ventrolateral medulla were carried out in urethane‐anaesthetised rats. A combined immunofluorescence and immunoperoxidase technique enabled an assessment of the tyrosine hydroxylase immunoreactivity, as well as an examination of the morphology of inspiratory and expiratory neurons in this part of the medulla oblongata. The results demonstrate: (a) that respiratory neurons in the rostral ventrolateral medulla of the rat are intermingled with catecholamine‐containing neurons of the C1 cell group, but are not themselves catecholamine‐containing; (b) that many non‐spinally projecting respiratory neurons have axonal arborisations within the ventrolateral medulla in the same region as the C1 cell group, other respiratory neurons, and neurons reported to have a cardiovascular function; and (c) that the dendrites of respiratory neurons in this region radiate throughout the ventrolateral medulla and frequently approach the ventral surface.