bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histaminergic system in the tree shrew brain
Authors: Airaksinen Matti S. , Flügge Gabriele , Fuchs Eberhard , Panula Pertti 
Published: January 2005

AbstractThis study mapped the histamine‐immunoreactive neuronal system in the brain of the tree shrew (Tupaia belangeri) and compared its structure with that of the rat and guinea pig. The histamine‐containing cell bodies lay in the posterior ventral hypothalamus in the tuberomammillary complex, as in the rodents. The morphology of this complex resembled that of the rat. The histaminergic axons projected to nearly all parts of the brain. The main ascending bundle ran ventromedially: the densest innervation was found in the ventral hypothalamus, preoptic area, septum, medial part of nucleus accumbens, and bed nucleus of the stria terminalis. High fiber densities were present in the amygdaloid nuclei and claustrum. Another pathway ran dorsomedially along the periventricular hypothalamus and sent fibers to all parts of the diencephalon. Part of these fibers followed the central gray to the midbrain and spread laterally below the inferior colliculus. Another descending pathway ran through the interfascicular and medial raphe nuclei to meet the pontine central gray. The densest fiber networks were seen in the dorsal tegmental and parabrachial nuclei, and around the locus coeruleus. Also the substantia nigra, interpeduncular and mesencephalic reticular nuclei, colliculi, and vestibular and raphe nuclei received a dense histaminergic innervation.The organization of the fibers in the tree shrew brain resembled more that in the guinea pig than that in the rat. As compared with the guinea pig, more fibers were present, particularly in the globus pallidus, central thalamus, and deep cerebellar nuclei. No fibers were seen in the outer layer of the piriform cortex. In Tupaia, a laminar organization of the fibers was evident in the hippocampus, in contrast to the rodents. Also, a dense periventricular fiber plexus was prominent.
Morphometric and freeze‐fracture studies on peripheral nerve in shiverer mice
Authors: Panagopoulos G. , King R. H. M. , Gabriel G. , Stolinski C. , Sofer D. , Lachapelle F. , Thomas P. K. 
Published: January 2005

AbstractObservations have been made on the peripheral nerves of shiverer (shi/shi) mice in comparison with control animals. Although this mutant lacks P1 myelin basic protein in peripheral and central myelin, myelin is defective only in the central nervous system. No ultrastructural abnormalities were observed in the shiverer nerves. Myelin spacing was normal. The density and distribution of intramembranous particles on the E and P faces of myelin and in the axolemma of myelinated and unmyelinated axons did not differ between the shiverer and control mice. Morphometric studies showed that external myelinated fiber diameter was significantly less and that myelin thickness was slightly but significantly greater in relation to axon diameter in the shiverer mice, suggesting a minor degree of axonal atrophy. It is concluded that P1 protein is not necessary for the formation and maintenance of the normal structure of peripheral myelin. The failure to detect differences in intramembranous particle density in myelin between shiverer and control mice indicates that P1 protein is not detected in freeze‐fracture preparations.
Density of neurons and synapses in the cerebral cortex of the mouse
Authors: Schüz Almut , Palm Günther 
Published: January 2005

AbstractQuantitative anatomical investigations provide the basis for functional models. In this study the density of neurons and synapses was measured in three different areas (8, 6, and 17) of the neocortex of the mouse. Both kinds of measurements were made on the same material, embedded in Epon/Araldit. In order to determine the synaptic density per mm3, the proportion of synaptic neuropil was also measured; it was found to be 84%. The cortical volume occupied by cell bodies of neurons and glia cells amounted to 12%, that by blood vessels to 4%.The total average was 9.2 × 104 neurons/mm3 and 7.2 × 108 synapses/mm3. About 11% of the synapses were of type II. The density of neurons increased with decreasing cortical thickness; thus the number of neurons under a given surface area was about constant. The synaptic density, on the other hand, was almost constant in the three areas, the number of synapses under a given cortical surface area tended, therefore, to increase with cortical thickness. The average number of synapses per neuron was 8,200, with a tendency to increase with increasing cortical thickness.Shrinkage of the tissue was also measured for various staining techniques. No shrinkage occurred during perfusion with 3.7% formaldehyde or with a solution of buffered paraformaldehyde and glutaraldehyde and during fixation in situ. Electron microscopical material showed almost no shrinkage, whereas Nissl‐preparations on paraffin‐embedded material had only 43% of their original volume. After Nissl stain on frozen sections the volume had shrunken to 68% and after Golgi impregnation and embedding in celloidin to 70%. The total volume of the neocortex was 112 mm3 (both hemispheres together). The total number of neurons was thus 1.0 × 107 and the total number of synapses 8.1 × 1010.
Prenatal development of retinocollicular projections in the rabbit: An HRP study
Authors: Crabtree John W. 
Published: January 2005

AbstractThe prenatal development of the rabbit's retinal projections to the superior colliculus (SC) was studied by using anterograde transport of horseradish peroxidase injected intraocularly. Fetuses aged embryonic day 21 (E21) to E29 and an adult rabbit were examined. Gestation in the rabbit is 30–31 days. On E21 contralaterally projecting retinal fibers invade across the entire SC. Their distribution is initially diffuse within the superficial laminae, but by E29 they have a distinct stratified appearance. Ipsilaterally projecting retinal fibers invade the rostral half of the SC on E21. By E23 they cover the entire SC and overlap the contralateral fibers both tangentially and radially. The ipsilateral fibers for the most part are sparsely distributed, but they form a dense focal distribution in the rostrolateral quarter of the SC. This focus straddles the stratum griseum superficiale/stratum opticum (SGS/SO) border. On E25 the ipsilateral fibers maintain their widespread distribution and focal rostrolateral concentration. By E27 they are excluded almost entirely from the caudal half of the SC and are reduced in density in the rostromedial quarter of the nucleus. On E29 the ipsilateral terminal field forms distinct patches and bands that are restricted to the rostrolateral quarter of the SC and are confined to the SGS/SO border. Thus, a few days before birth the pattern and location of the ipsilateral retinocollicular projection resemble those seen in the adult. The early widespread distribution of the ipsilaterally projecting retinal fibers to the SC and their eventual restriction in the fetal rabbit are consistent with the development of this projection in other mammalian orders.
Avian somatosensory system: II. Ascending projections of the dorsal column and external cuneate nuclei in the pigeon
Authors: Wild J. Martin 
Published: January 2005

AbstractThe ascending projections of the dorsal column and external cuneate nuclei (DCN/CuE) in the pigeon were investigated in anterograde tracing experiments by using autoradiography or wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). The results show that the majority of ascending projections decussate via internal arcuate fibers to form a contralateral medial lemniscus which ascends in a ventral position. In the brainstem, terminal fields were observed in the ventral lamella of the inferior olive (OI), the parabrachial nuclei (PB) of the dorsolateral pons, the intercollicular nucleus (ICo) of the midbrain, and the nucleus pretectalis diffusus (PD). In the diencephalon there were terminal fields in the strata cellulare externum and internum (SCE and SCI) of the caudal hypothalamus; in the intercalated (ICT), ventrolateral (VLT), and reticular nuclei of the ventral thalamus; in the nuclei principalis precommissuralis (PPC), spiriform medialis (SpM), and dorsolateralis posterior, pars caudalis (cDLP) of the caudal thalamus; and in the nuclei dorsalis intermedius ventralis anterior (DIVA), dorsolateralis posterior, pars rostralis (rDLP), dorsolateralis anterior (DLA), and dorsolateralis anterior, pars medialis (DLM) of the rostrodorsal thalamus.The origins of these projections within the DCN/CuE complex were verified in retrograde tracing experiments with WGA‐HRP and were found to be partly differentiable with respect to their targets. The projections to DIVA, rDLP, DLA, DLM, cDLP, and SpM arise from all rostrocaudal levels of the DCN/CuE complex; those to ICo arise from caudomedial nuclear regions, while those to the hypothalamus and ventral thalamus arise from rostrolateral nuclear regions. Projections to PB arise from lamina I neurons of the dorsal horn of upper cervical spinal cord segments and from CuE. No evidence was found of a projection to the cerebellum.The distribution of the cells of origin of the medial lemniscus (ML) within the DCN/CuE complex was found to be largely coextensive with the areas of termination of primary spinal (Wild: J. Comp. Neurol. 240:377–395, '85) and some trigeminal (Dubbledam and Karten: J. Comp. Neurol. 180:661–678, '78) afferents. Furthermore, the areas of termination of the ML within the rostrodorsal and caudal thalamus are also either coextensive or closely associated with nuclei which provide a somatosensory projection to separate regions of the telencephalon (Wild: Brain Res. 412:205–223, '87). There are thus clear similarities in the overall pattern of somatosensory projections in the pigeon and in many mammalian species.
Neuronal localization of cholecystokinin mRNA in the rat brain by using in situ hybridization histochemistry
Authors: Ingram Susan M. , Krause Rudolph G. , Baldino Frank , Skeen Leslie C. , Lewis Michael E. 
Published: January 2005

AbstractThe distribution of cholecystokinin (CCK) mRNA in the rat brain was determined by means of in situ hybridization histochemistry. Our results demonstrate a widespread distribution of neurons containing CCK mRNA throughout the rat brain. Hybridization‐positive neurons were distributed throughout the neocortex, olfactory bulb, claustrum, amygdala, the dentate gyrus and hippocampus proper, and several subnuclei of the thalamus and the hypothalamus. The most abundant and most heavily labeled neurons were found in the endopiriform/piriform cortex, tenia tecta, and the ventral tegmental area. The distribution of neurons positive for CCK mRNA paralleled that of CCK‐like immunoreactive neurons. These results detail the distribution of CCK mRNA and clearly identify the existence of CCK‐synthesizing neurons in regions such as the paraventricular and supraoptic nuclei of the hypothalamus, where the presence of CCK cell bodies was previously uncertain.
Relationship between isthmotectal fibers and other tectopetal systems in the leopard frog
Authors: Gruberg Edward R. , Wallace Mark T. , Waldeck Robert F. 
Published: January 2005

AbstractWe studied the relationship of isthmotectal input to other tectal afferent fiber systems in three ways. (1) Using horseradish peroxidase (HRP) histochemistry, we determined the nonretinal inputs to the superficial tectum. In different sets of animals we (a) applied HRP to the tectal surface; (b) inserted HRP crystals into the tectum; (c) injected small volumes of HRP solutions into the superficial tectum. N. isthmi accounts for more than 65% of the nonretinal extrinsic input in the superficial tectal layers. One set of fibers from the contralateral n. isthmi projects to the most superficial layer. Fibers from posterior thalamus and tegmentum project to both superficial and deeper layers in the tectum, but not to the most superficial layer. The ipsilaterally projecting isthmotectal fibers terminate in the deeper superficial layers. (2) We investigated the relationship between retinofugal and contralaterally projecting isthmotectal pathways. We orthogradely labelled n. isthmi fibers by unilateral HRP injections into n. isthmi, and we also labelled retinal fibers by injecting tritiated 1‐proline into both eyes. In such animals contralaterally projecting isthmotectal fibers cross in the dorsal posterior region of the optic chiasm. From the chiasm to the tectum isthmotectal fibers and retinofugal fibers are admixed. (3) We determined whether other fiber systems cross with contralaterally projecting isthmotectal fibers. We cut the posterior part of the optic chiasm and applied HRP crystals to the cut. Only n. isthmi and retina are retrogradely labelled.
Axonal trajectories and terminations of on‐ and off‐cells in the cat lower brainstem
Authors: Mason P. , Fields H. L. 
Published: January 2005

AbstractTwo physiologically defined classes of pontomedullary raphe neurons were intracellularly labeled in order to determine the target nuclei of their axonal projections. In the lightly anesthetized cat, cells either increased (on‐cells) or decreased (off‐cells) their discharge rate during the paw withdrawal reflex evoked by noxious pinch or heat. On‐ and off‐cells were injected with horseradish peroxidase and the initial course of labeled axons through the lower brainstem was reconstructed.On‐cell projections to the pontomedullary raphe and medial reticular nuclei were sparse. On‐cells projected densely to regions of the lateral reticular formation and the ventrolateral medulla at both rostral and caudal medullary levels. In general, on‐cells had few collaterals and sparse axonal swellings.In contrast to on‐cells, most off‐cells had axons that collateralized densely within the brainstem raphe and adjacent reticular formation. Such collaterals were either local, within the neuron's dendritic field, or distant, involving a projection of 1–8 mm. One off‐cell had a dense terminal field within the sensory trigeminal complex, a projection that may subserve the inhibition of trigeminal sensory neurons produced by raphe magnus stimulation. Well‐labeled off‐cells had numerous collaterals and dense regions of axonal swellings.In summary, off‐cells terminated densely in the raphe magnus and adjacent reticular formation whereas on‐cells projected predominantly to the ventrolateral medulla, a region implicated in autonomic control. Local off‐cell collaterals provide an anatomical substrate that would enable off‐cells to coordinate the activity of on‐ and off‐cells through synaptic contacts.
Distribution of cat‐301 immunoreactivity in the frontal and parietal lobes of the macaque monkey
Authors: McGuire Philip K. , Hockfield Susan , Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractThe distribution of the monoclonal antibody Cat‐301 was examined in the frontal and parietal cortex of macaque monkeys. In both regions the distribution was uniform within cytoarchitecturally defined areas (or subareas) but varied between them. In all areas, Cat‐301 labeled the soma and proximal dendrites of a restricted population of neurons. In the frontal lobe, Cat‐301‐positive neurons were intensely immunoreactive and present in large numbers in the motor cortex (area 4), premotor cortex (area 6, excluding its lower ventral part), the supplementary motor area (SMA), and the caudal prefrontal cortex (areas 8a, 8b and 45). In the parietal lobe, large numbers of intensely immunoreactive neurons were evident in the post‐central gyrus (areas 1 and 2), the superior parietal lobule (PE/5), and the dorsal bank (PEa), fundus (IPd), and deep half of the ventral bank (POa(i)) of the intraparietal sulcus (IPS).Two major patterns of laminar distribution were evident. In motor, supplementary motor, premotor (excluding the lower part of its ventral division), and the caudal prefrontal cortex (Walker's areas 8a, 8b and 45), and throughout the parietal cortex (with the exception of area 3), Cat‐301‐positive neurons were concentrated in the lower part of layer III and in layer V. The laminar positions of labeled cells in these areas were remarkably constant, as were the proportions of labeled neurons that had pyramidal and nonpyramidal morphologies (means of 30.2% and 69.8%, respectively). In contrast, in prefrontal areas 9, 10, 11, 12, 13, 14, and 46, in the cingulate cortex (areas 23, 24 and 25), and in the lower part of the ventral premotor cortex, Cat‐301‐positive neurons were spread diffusely across layers II to VI and a mean of 3.6% of the labeled neurons were pyramidal while 96.4% were nonpyramidal. Area 3 was unique among frontal and parietal areas, in that the labeled neurons in this area were concentrated in layers IV and VI.The areas in the frontal lobe which were heavily labeled are thought to be involved in the control of somatic (areas 4 and 6) and ocular (areas 8 and 45) movements. Those in parietal cortex may be classified as areas with somatosensory functions (1, 2, PE/5, and PEa) and areas which may participate in the analysis of visual motion (Pandya and Seltzer's IPd and POa(i), which contain Maunsell and Van Essen's VIP). The parietal somatosensory areas are connected to frontal areas with somatic motor functions, while POa(i) is interconnected with the frontal eye fields (8a and 45). Both POa(i) and the frontal eye fields are known to receive inputs from visual areas specialized for motion analysis.Cat‐301 may heavily label neurons in frontal and parietal areas that are broadly concerned with the control of somatic and ocular movements and the processing of the sensory information on which their normal execution depends.
Immunohistochemical characterization of pelvic neurons which project to the bladder, colon, or penis in rats
Authors: Keast J. R. , de Groat W. C. 
Published: January 2005

AbstractRetrograde‐tracing and immunohistochemical techniques were used in combination to investigate the types of putative transmitters in pelvic neurons that project to the bladder, colon or penis of rats. In addition, populations of axon varicosities associated with these neurons were characterized.Subpopulations of neurons in colchicine‐treated major pelvic ganglia and accessory ganglia of male rats contained immunoreactivity (IR) for tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), or enkephalin (ENK), while types of immunoreactivity found in major groups of varicose axons were ENK, cholecystokinin (CCK), and somatostatin (SOM). Substance P (SP)‐IR varicose axons were much less common. Bladder and colon neurons were similar in a number of ways. Many neurons contained NPY‐IR (≥50%), fewer contained TH‐IR (25–30%), and even fewer contained ENK‐IR (5–15%) or VIP‐IR (5–10%); many neurons were associated with baskets of ENK‐IR varicosities (50–65%) and fewer neurons were surrounded by CCK‐ or SOM‐IR varicosities (30–35%). Colon neurons differed from penis neurons in having a slightly larger proportion that contained ENK‐IR (10–15%, compared with 1–3%). Penis neurons were markedly different from the other two groups in additional ways. More than 90% of them contained VIP‐IR, whereas only 5–7% contained NPY‐IR and none were immunoreactive for TH. Furthermore, although the proportion of penile neurons associated with many ENK‐IR varicosities was similar to the bladder and colon neurons (45–50%), they were rarely seen close to CCK‐ or SOM‐IR varicose axons.These studies describe similarities and differences in the histochemical properties of neurons which project to the bladder, colon, or penis and of the varicose axons associated with those neurons. This gives further insights into the possible transmitter mechanisms involved in the regulation of different pelvic functions.
Lesions of the basal forebrain alter stimulus‐evoked metabolic activity in mouse somatosensory cortex
Authors: Ma Wu , Höhmann Christine F. , Coyle Joseph T. , Juliano Sharon L. 
Published: January 2005

AbstractThe role that acetylcholine plays in processing sensory stimuli is beginning to be characterized; however, morphological correlates of cholinergic effects on activity patterns in sensory cortex are not available. To study this problem, unilateral neurotoxic lesions that depleted the neocortex of acetylcholine were made in the basal forebrains of mice. The aim of these experiments was to study the effect of cholinergic depletion on stimulus‐evoked activity in the barrel field of the mouse somatosensory cortex. One month following the lesion, 2‐deoxyglucose (2DG) experiments were conducted on the lesioned and on normal mice while the animal received bilateral stimulation to the C3 whisker. The tissue was processed for acetylcholinesterase and cytochrome oxidase histochemistry and 2DG autoradiography. Evaluation of the column‐like 2DG label evoked in the somatosensory cortex revealed that the activity on the lesioned side was significantly reduced in dimension and intensity from that in the normal hemisphere. On the normal side, the activated barrels averaged 641 μm in tangential width, were 76.5% above background in density, and extended from lamina I‐V. On the lesioned side, the activated barrels were 485 μm in tangential width, 65.4% above background in density, and extended from lamina II–V. In other cortical regions, outside the stimulus‐evoked barrel field, 2DG activity values were similar on the normal and lesioned side. Additionally, both the pattern and intensity of the cytochrome oxidase staining within the barrel field displayed no differences in either hemisphere. These studies suggest that acetylcholine plays a significant role in the processing of somatosensory information. Neurotoxic lesions that diminish cortical cholinergic innervation cause a reduction of stimulus‐evoked activity levels, while underlying metabolic activity is either not affected or recovers over time.
Primate spinothalamic pathways: III. Thalamic terminations of the dorsolateral and ventral spinothalamic pathways
Authors: Apkarian A. Vania , Hodge Charles J. 
Published: January 2005

AbstractThe termination sites of the dorsolateral (DSTT) and ventral (VSTT) spinothalamic pathways were determined by using anterograde transport of horseradish peroxidase from the lumbar spinal cord in primates. One animal had no spinal cord lesion, while of two other animals, one received a midthoracic dorsolateral funiculus lesion, and the other received a midthoracic ventral quadrant lesion contralateral to the injection. The thalamic label in the animal with no spinal cord lesion was much less than the label in the two animals with spinal lesions. Moreover, in the animals with spinal lesions, HRP‐labeled cells were found within the thalamus. Therefore, the remaining six animals received ipsilateral hemisections and bilateral dorsal column lesions, irrespective of the contralateral lesions.The thalamic label in the animals without contralateral lesions were assumed to represent the total spinothalamic input to the diencephalon. In these animals, label was located mainly in suprageniculate and pulvinar oralis, caudal and oral divisions of ventral posterior lateral nucleus, the lateral half of ventral posterior inferior nucleus, and zona incerta, while in the medial thalamus label was primarily in two distinct bands in medial dorsal nucleus and in the posterior dorsal protion of central lateral nucleus. Scattered lighter labeling was found in other thalamic nuclei. The pattern of terminal labeling observed in the ventral posterior lateral region was arranged in patches, while elsewhere in the thalamus a more uniform labeling pattern was observed.The thalamic label in animals with contralateral ventral quadrant lesions represented the terminations of the DSTT, while the label in animals with contralateral dorsolateral funiculus lesions represented VSTT terminations. The labeling pattern was similar between these two groups. However, there were small differences between them. These results indicate that DSTT and VSTT terminations largely overlap and innervate the lateral and medial thalamus.