bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corticothalamic and corticotectal somatosensory projections from the anterior ectosylvian sulcus (SIV cortex) in neonatal cats: An anatomical demonstration with HRP and 3H‐leucine
Authors: McHaffie John G. , Kruger Lawrence , Clemo H. Ruth , Stein Barry E. 
Published: January 2005

AbstractCorticothalamic and corticotectal projections from the anterior ectosylvian sulcus (AES) in neonatal cats were studied with anterograde and retrograde neuroanatomical techniques. When the injection site was relatively restricted to the sulcal walls and fundus of the rostral AES (i.e., the SIV cortex), heavy ipsilateral thalamic label was observed in the medial subdivision of the posterior group, in the suprageniculate nucleus, and in the external medullary lamina. No terminal label was seen in the contralateral thalamus although the contralateral homotopic cortex was heavily labeled. Within the ventrobasal complex (VB), dense axonal label was observed in fascicles that traversed VB, but only light terminal label was observed within VB itself. However, in cases where the tracer spread into adjacent SII, terminal label in VB was pronounced. Similarly, when the injection site extended into auditory cortex, terminal label was observed in the lateral and intermediate subdivisions of the posterior group.Rostral AES injections produced distinct, predominantly ipsilateral, terminal label in the superior colliculus that was distributed in two tiers: a discontinuous band in the stratum griseum intermedium and a more diffuse band in stratum griseum profundum. Caudally, dense terminal label was seen in the intercollicular zone and dorsolateral periaqueductal gray. When the injection site did not include rostral AES, no label was observed in the superior colliculus. Horseradish peroxidase injections into the superior colliculus of neonates produced retrogradely labeled neurons throughout the AES, but none was found on the crown of the gyrus where SII is located. Thus, the neonatal corticotectal somatosensory projection arises exclusively from AES and parallels that found in adults.These data indicate that the elaboration of a major descending somatosensory pathway from AES to the thalamus and midbrain is largely a prenatal event. The in utero anatomical maturation of the corticofugal projections from SIV cortex to the superior colliculus contrasts with the protracted postnatal development of the corticotrigeminal projections from SI cortex but is consistent with the mature anatomical state of ascending trigeminotectal projections.
Quantitative study of the Purkinje cell dendritic spines in the rat cerebellum
Authors: Napper R. M. A. , Harvey R. J. 
Published: January 2005

AbstractThe number of spines on an individual Purkinje cell in the cerebellar cortex of the rat was determined by stereological methods. Investigations were based on thin section electron micrographs, freeze fracture replicas, and horseradish peroxidase labeled cells. Purkinje cell dendritic spines in our embedded material had a mean length of 1.4 ± 0.05 μm and mean neck and head diameters of 0.22 ± 0.01 μm and 0.45 ± 0.02 μm, respectively. From these dimensions, an estimate of spine volume in embedded material of 0.132 μm3 was obtained. The density of dendritic spines in our fixed material was 8.15 × 108 or 7.24 × 108 per μl of molecular layer from volume fraction and density per mm2, respectively. The number of spines per linear micron of Purkinje cell spiny branchlet was 17.2 from freeze fracture and 17.6 from horseradish peroxidase labeled dendrites. These all indicate that there are between 154,000 and 175,000 spines on the dendritic tree of each Purkinje cell, considerably more than previously reported for the rat.
Number of parallel fiber synapses on an individual Purkinje cell in the cerebellum of the rat
Authors: Napper R. M. A. , Harvey R. J. 
Published: January 2005

AbstractIn the present study, stereological techniques applied to electron micrographs of the molecular layer of the rat cerebellum have been used to estimate the number of parallel fiber synapses on the dendritic tree of a single Purkinje cell. Quantitative features of the parallel fiber to Purkinje cell dendritic spine synapses and of the parallel fibers were investigated as a preliminary to estimating the number of synapses. Parallel fiber to Purkinje cell synapses are flattened disclike structures with a mean axial ratio of 1.47 and a mean diameter of 319 μm in fixed tissue. The density of synapses in our fixed material was 8.17 × 108 per μl of molecular layer. Determination of the length density of the synapses per unit area of micrograph indicated a synapse density of 8.03 × 108 per μl. These densities give a total number of synapses per Purkinje cell of 1.74 × 105 and 1.71 × 105, respectively. Estimation of the number of parallel fiber varicosities and of varicosity length gave a density of 9.31 × 108 varicosities per μl of molecular layer and determining the mean number of parallel fiber to Purkinje cell synapses per varicosity gave a synapse density of 9.82 × 108 per μl, equivalent to 2.09 × 105 per Purkinje cell. The reasons why this estimate is likely to be too high are discussed. We conclude that there are some 175,000 parallel fiber synapses on an individual Purkinje cell dendritic tree in the cerebellar cortex of the rat, considerably more than previously reported.
Anatomy of the adrenergic system in the medulla oblongata of the tree shrew: PNMT immunoreactive structures within the nucleus tractus solitarii
Authors: Mittendorf Andrea , Denoroy Luc , Flügge Gabriele 
Published: January 2005

AbstractThe adrenergic system in the medulla oblongata of tree shrews was investigated by immunocytochemistry with an antibody against phenylethanolamine‐N‐methyltransferase. Two groups of adrenegic cells, which are equivalent to those of other species, were detected: Group C1 in the ventrolateral medulla and group C2 in the dorsomedial medulla.Adrenergic cells in C1 are located around the lateral reticular nucleus or between its subdivisions. They are mostly multipolar with branched processes. In group C2, some immunoreactive cell bodies smaller than those in C1 and many nerve terminals are found in the motor nucleus of the vagus, but most of the adrenergic cells and fibers are observed in the nucleus tractus solitarii. The cytoarchitecture of this nucleus resembles that described before for the rhesus monkey. In contrast to the rat, the subnucleus gelatinosus, which according to other authors receives cardiac and gastric afferents, is a prominent structure in immunocytochemically as well as conventionally stained sections. Adrenergic cell bodies and their fibers form a ring around this nucleus, but no immunoreactive structures are found within it. In the dorsomedial part of the nucleus tractus solitarii, adrenergic neurons are accumulated. They are often located in close proximity to blood vessels. Elongated immunoreactive neurons in the medial subdivision of the nucleus also seem to project in the direction of the dorsal area.Our data give new information about the adrenergic system in the medulla oblongata, especially in the nucleus tractus solitarii of the tree shrew, a species that provides a useful model of a small primate brain.
Effects of kynurenate and other excitatory amino acid antagonists as blockers of light‐ and kainate‐induced retinal rod photoreceptor disc shedding
Authors: Besharse Joseph C. , Spratt Gwendolyn , Reif‐Lehrer Liane 
Published: January 2005

AbstractPhotoreceptor disc shedding in the retina involves detachment of discs from distal outer segments and phagocytosis of those discs by adjacent pigment epithelial cells. The disc‐shedding process balances the continuous renewal of photosensitive membrane. In amphibians, rod disc shedding normally is light‐stimulated. However, excitatory amino acids such as kainate stimulate disc shedding independent of a dark‐light transition. Excitatory amino acid‐induced disc shedding is accompanied by toxic changes within the retina. To evaluate the possible role of an endogenous excitatory amino acid in the regulation of light‐evoked disc shedding, we examined the effects of excitatory amino acid antagonists on kainate‐induced and light‐evoked disc shedding and on retinal toxicity. Using eyecups from Rana pipiens, we found that kynurenate, D‐O‐phosphoserine, and cis‐2,3‐piperidine dicarboxylic acid (cis‐PDA) all block both the neurotoxic and disc‐shedding effects of kainate. Kynurenate and D‐O‐phosphoserine, but not cis‐PDA, also block light‐evoked disc shedding. Our analysis suggests that kynurenate blocks the mechanism by which light “triggers” disc shedding rather than directly inhibiting disc detachment and phagocytosis. The observation that cis‐PDA antagonizes the effects of kainate, but not light, suggests that the receptor mediating the kainate effect on disc shedding may not be involved in the normal initiation of the response by light. In contrast, our data on kynurenate suggest that it antagonizes an endogenous mechanism involved in the normal control of disc shedding. Thus, analysis of the differences between cis‐PDA and kynurenate as antagonists in the retina may yield important insight into the mechanism by which light initiates disc shedding.
Morphological and electrophysiological identification of gigantocellular tegmental fied neurons with descending projections in the cat: II. Bulb
Authors: Mitani Akira , Ito Keihachiro , Mitani Yuko , McCarley Robert W. 
Published: January 2005

AbstractThere are three different descending projections from the bulbar gigantocellular tegmental field (BFTG) in the cat, as defined by intracellular recording and intracellular horseradish peroxidase (HRP) techniques. The first pathway arises from neurons which send axons to the contralateral medial longitudinal fasciculus (cMLF neurons); cMLF neurons show excitatory postsynaptic potentials (EPSPs) after stimulation of the ipsilateral pontine gigantocellular tegmental field (PFTG). Most cMLF neurons have large ellipsoid‐polygonal somata (mean, 56.8 μm), thick axons (average diameter, 3.09 μm), mostly non‐spiny dendrites and dendritic fields flattened in the anteroposterior direction. No cMLF neurons with axon collaterals in the BFTG are present in the data of this study. The second pathway arises from neurons which send axons to the ipsilateral MLF (iMLF neurons); iMLF neurons show EPSPs after stimulation of the ipsilateral PFTG. Most iMLF neurons have large ellipsoid‐polygonal somata (mean, 60.2 μm), thick axons (average diameter, 3.00 μm), mostly non‐spiny dendrites and dendritic fields that are only slightly flattened in the anteroposterior direction. As with cMLF neurons, no iMLF neurons with axon collaterals in the BFTG are present in the data of this study. The third pathway arises from neurons that send axons directly into the ipsilateral caudal bulbar reticular formation (iBRF neurons). Most iBRF neurons have smaller ellipsoid‐polygonal somata (mean, 38.6 μm), thinner axons (average diameter, 1.84 μm), mostly nonspiny dendrites, and dendritic fields that are flattened in the anteroposterior direction. In contrast to cMLF and iMLF neurons, axon collaterals are present in 73% of iBRF neurons. About half of iBRF neurons have bifurcated axon collaterals with both anterior and posterior projections, and in these neurons antidromic spike potentials are elicited by stimulation of the ipsilateral PFTG.
Localization of immunoreactive GABA and enkephalin and NADPH‐Diaphorase‐positive neurons in fetal striatal grafts in the quinolinic‐acid‐lesioned rat neostriatum
Authors: Roberts Rosalinda C. , Difiglia Marian 
Published: January 2005

AbstractFetal striatal tissue grafts have been shown to partially reverse the biochemical and behavioral deficits induced by excitotoxic lesions. To determine if grafted striatal neurons contain neurochemical markers similar to those in neurons in the caudate nucleus and to establish the morphological characteristics and relative frequency of labeled neurons in the grafts, the localization of immunoreactive GABA and leucine‐enkephalin (ENK) and of NADPH‐diaphorase (NADPH‐d) activity was examined in fetal striatal grafts at the light and electron microscopic levels. Striatal tissue from 17‐day fetuses was grafted into the caudate nucleus of adult rats 1 week after intracaudate injections of either a low or high dose of quinolinic acid. At the light microscopic level, immunoreactive GABA and ENK and NADPH‐d‐positive neurons, processes, and punctate structures were present within adjacent sections of the same grafts. The frequency and morphological features of these labeled cell populations were similar in grafts placed into either minimally or extensively lesioned striata. Immunoreactive GABA and ENK neurons in the grafts constituted 28% and 13.5%, respectively, of the neuronal population of the graft and their mean diameters were 22 and 14% larger, respectively, than neostriatal neurons that contained the same chemical markers. NADPH‐d‐positive neurons in the grafts formed 3.5% of total grafted neurons and exhibited characteristics of neostriatal NADPH‐d‐containing aspiny cells, including medium‐sized somata, indented nuclei, and varicose dendrites.At the electron microscopic level most GABA‐positive neurons in the grafts contained indented nuclei and most immunoreactive ENK somata had unindented nuclei. Dendrites and dendritic spines with GABA or ENK immunoreactivity were present in the grafts where they were postsynaptic to unlabeled axons. Immunoreactive GABA and ENK axon terminals formed synapses with unlabeled neuronal profiles in the grafts. These findings demonstrate that fetal striatal grafts contain chemically defined neuronal populations that form synaptic connections within the graft and share some features with corresponding cell groups in the neostriatum. These results provide an anatomical basis for the graft‐induced recovery from behavioral and biochemical deficits caused by instrastriatal lesions reported in other studies.
Optic synapse number but not density is constrained during regeneration onto surgically halved tectum in goldfish: HRP‐EM evidence that optic fibers compete for fixed numbers of postsynaptic sites on the tectum
Authors: Hayes William Pär , Meyer Ronald L. 
Published: January 2005

AbstractThe number of optic synapses in the half tectum of goldfish was counted by using an improved HRP‐labeling protocol and a columnar sampling method that spanned the entire optic innervation layer, S‐SO‐SFGS. It was previously found by using this procedure in intact tectum that the normal number of optic synapses was regenerated by 30 days and maintained thereafter even in the absence of impulse activity. This suggested that the number of synapses in this system was intrinsically fixed. In order to examine whether this limit was imposed by optic fibers or by target cells, optic synapses were counted in surgically halved tecta which received compressed optic projections consisting of regenerating optic fibers from the entire retina. We reasoned that if synapse number is a function of the number of afferents, then there should be twice the normal number of optic synapses per column; on the other hand, if their number is fixed by target, then their number per column should be normal.We found that the number of optic (labeled) synapses was normal in sample columns from fish at 70 days and 160 days after optic nerve crush. Thus, retinal ganglion cells, on average, formed half as many synapses on the half tectum compared to intact tectum, indicating the number of optic synapses was limited by the tectum. The number of nonoptic (unlabeled) synapses was also found to be normal. By contrast, the S‐SO‐SFGS was found to be 88–103% thicker compared to normal fish, apparently because of a 20‐fold increase in the number of optic fibers. As a result, the density of synapses was about half normal in half tecta, and so, in contrast to synapse number, synaptic density is not constrained during regeneration.We infer from these data that optic fibers compete for limited numbers of postsynaptic sites during regeneration and suggest that this competition promotes neural map refinement and the various plasticities described for this projection.
Electron microscope study of Golgi‐stained cells in lamina II of the rat spinal dorsal horn
Authors: Todd Andrew J. 
Published: January 2005

AbstractSeven Golgi‐stained cells in lamina II of the rat spinal dorsal horn were examined by electron microscopy. One of the cells studied was an islet cell, two were stalked cells, and the remaining four cells could not be classed into either group.The islet cell and three of the unclassified cells possessed presynaptic dendrites and formed synapses onto a variety of dendritic spines and shafts within lamina II. The axons of the islet cell and of one of the unclassified cells formed symmetric axodendritic synapses mainly onto dendritic shafts.The two stalked cells and the remaining unclassified cell did not possess vesicle‐containing dendrites. This last cell bore some resemblance to a stalked cell and may have represented an atypical example of one.Most of the synapses involving the cells took place outside synaptic glomeruli, but all seven cells were postsynaptic to central axons within glomeruli and in most cases to both type I and type II central axons, suggesting a monosynaptic input from myelinated and unmyelinated primary afferent axons. In addition, most of the cells were postsynaptic to vesicle‐containing dendrites.It is concluded that certain cells, which do not belong to the stalked or islet classes, possess presynaptic dendrites and function as presumed inhibitory interneurones within lamina II. The target of the cells with presynaptic dendrites includes other cells within lamina II and may also include cells in deeper laminae of the dorsal horn. Further evidence will be needed in order to determine whether all cells in lamina II that do not possess presynaptic dendrites form a single functional class.
Development of the rat thalamus: II. Time and site of origin and settling pattern of neurons derived from the anterior lobule of the thalamic neuroepithelium
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractShort‐survival, sequential, and long‐survival thymidine radiograms of rat embryos, fetuses, and young pups were analyzed in order to examine the time of origin, settling pattern, and neuroepithelial site of origin of the anterior thalamic nuclei–the lateral dorsal (lateral anterior), anterodorsal, anteroventral and anteromedial nuclei–and of two rostral midline structures–the anterior paraventricular and paratenial nuclei. The neurons of the lateral dorsal nucleus are generated over a 3‐day period between days E14‐E16 and their settling pattern displays a combined lateral‐to‐medial and dorsal‐to‐ventral neurogenetic gradient. The bulk of the neurons of the anteroventral nucleus are generated over a 3‐day period between days E15‐E17 and settle with an oblique lateral‐to‐medial and ventral‐to‐dorsal neurogenetic gradient. The bulk of the neurons of the anteromedial nucleus are generated over a 2‐day period between days E16‐E17 and show the same settling pattern as the anteroventral nucleus. The neurons of the anterodorsal nucleus are generated over a 3‐day period between days E15‐E17 and show a lateral‐to‐medial neurogenetic gradient. The bulk of the neurons of the central part and lateral part of the paraventricular nucleus are generated over a 2‐day period (E16‐E17 and E17‐E18, respectively) and each part displays a ventral‐to‐dorsal neurogenetic gradient. Finally, the bulk of the neurons of the paratenial nucleus are generated over a 4‐day period between days E15‐E18 and settle with a lateral‐to‐medial neurogenetic gradient.Observations are presented that the anterior thalamic nuclei, constituting the distinct “limbic thalamus,” derive from a discrete neuroepithelial source. This is the crescent‐shaped germinal matrix lining the diencephalic (medial) wall of the hitherto unrecognized anterior transitional promontory, which we call the anterior thalamic neuroepithelial lobule. On day E16 three migratory streams leave the anterior neuroepithelial lobule and, on the basis of their labeling pattern in relation to the neurogenetic gradients of the anterior thalamic nuclei, they are identified, from dorsal to ventral, as the putative migratory streams of the anterodorsal, anteroventral, and lateral dorsal nuclei. On day E17 the putative migratory stream of the anteromedial nucleus appears to leave the same neuroepithelial region that on the previous days was the source of the anteroventral nucleus. Dorsally, two neuroepithelial patches persist after day E17 and these are identified as the putative cell lines of the anterior paraventricular and paratenial nuclei.
Serotoninlike immunoreactivity in the central and peripheral nervous system of the scale worm Harmothoe imbricata (polychaeta)
Authors: Miron Marie‐José , Anctil Michel 
Published: January 2005

AbstractThe distribution of serotoninergic neurons in the nervous system of the scale worm Harmothoe imbricata was visualized in the anterior half of the body by the peroxidase‐antiperoxidase (PAP) immunohistochemical method with a specific antiserotonin antibody. Immunoreactive neuronal somata were localized in discrete ganglion cell masses of the dorsally situated cerebral ganglion and in segmental ganglia of the ventral nerve cord. They also make up the majority of neurons present in the parapodial ganglia. Large and small varicose fibers stained in the neuropile of all the above‐mentioned ganglia but also in interganglionic connectives and segmental nerves. On the basis of soma size and location and of fiber distribution, the reactive neurons were identified as primarily interneuronal with a few motoneurons and presumptive afferent neurons. The presence of a motor component was substantiated by observations of several reactive varicose fibers spread over longitudinal muscle layers of the trunk. In addition, neurites of the subepidermal nerve plexus and enterochromaffinlike cells of the gut epithelium reacted with the serotonin antibody. It is concluded that serotoninergic pathways are ubiquitous elements in the organization of the central and peripheral nervous system of this polychaete. The significance of these findings in relation to other annelid groups and to the physiological role of serotonin is discussed.