bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for subdivisions in the human suprachiasmatic nucleus
Authors: Mai J. K. , Kedziora O. , Teckhaus L. , Sofroniew M. V. 
Published: January 2005

AbstractThe human suprachiasmatic nucleus was analysed by immunohistochemical demonstration of various substances in combination with 3‐dimensional computerized reconstruction and video overlay facilities. In the human, the suprachiasmatic nucleus is not as compact as in the rodent. Its boundaries are not easily delineated using conventional stains, and it shows no obvious cytoarchitectonic structure. However, based on its chemoarchitecture, the human suprachiasmatic nucleus can be apportioned into five major subdivisions: Dorsal, comprising a crescent shaped mass of densely packed neurophysin/vasopressin‐neurons as well as neurotensin‐neurons, and also containing 3‐fucosyl‐N‐acetyl‐lactosamine (FAL)‐positive neurons in its medial part. Central, occupying the core of the nucleus and consisting precisely of a region devoid of neurophysin/vasopressin neurons but demarcated by calbindin, synaptophysin, and a circumscribed cluster of vasoactive intestinal polypeptide‐neurons and containing neurotensin neurons as well. Anteroventrally this division also contains some intermingled neurons positive for neurotensin, neuropeptide Y, somatostatin, and FAL. Ventral, extending from the anterior extreme of the preoptic recess caudolaterally to a field between the optic chiasm and the anteroventral margin of the supraoptic nucleus. This subdivision is specified by synaptophysin, calhindin, and substance P immunoreactivity and is almost free of glial fibrillary acidic protein. From its rostral portion, fibers immunoreactive for calbindin, vasoactive intestinal polypeptide, synaptophysin, and substance P protrude deeply into the optic chiasm. Medial, comprising a thin band between the subependymal zone and the dorsal subdivision, containing scattered somatostatin neurons. External, extending as a band around the dorsal and lateral borders of the nucleus, containing astrocytes expressing the FAL‐epitope and scattered neurophysin/vasopressin and neurotensin neurons.These findings indicate that the human suprachiasmatic nucleus contains well‐defined subdivisions with different, chemically specific, connections and provides a basis for comparing these subdivisions with the structure and function of subdivisions previously described for the suprachiasmatic nucleus in experimental animals. In addition, the findings strengthen the concept that the human suprachiasmatic nucleus generates and expresses circadian rhythms in a manner similar to that documented for the suprachiasmatic nucleus in experimental animals, and suggest that different subdivisions may subserve specific functional roles.
Organization of pyramidal neurons in area 17 of monkey visual cortex
Authors: Peters Alan , Sethares Claire 
Published: January 2005

AbstractIn sections of area 17 of monkey visual cortex treated with an antibody to MAP2 the disposition of the cell bodies and dendrites of the neurons is readily visible. In such preparations it is evident that the apical dendrites of the pyramidal cells of layer VI form fascicles that pass into layer IV, where most of them gradually taper and form their terminal tufts. In contrast, the apical dendrites of the smaller layer V pyramidal cells come together in a more regular fashion. They form clusters that pass through layer IV and into layer II/III where the apical dendrites of many of the pyramidal cells in that layer add to the clusters. In horizontal sections taken through the middle of layer IV, these clusters of apical dendrites are found to have an average center‐to‐center spacing of about 30 μm, and it is proposed that each cluster of apical dendrites represents the axis of a module of pyramidal cells that has a diameter of about 30 μm and contains about 142 neurons.The MAP2 antibody reaction also reveals that some pyramidal cells in layers IVA and IVB have their cell bodies arranged into cones. There are about 118 such cones beneath 1 mm2 of cortical surface and the apical dendrites of the pyramidal cells within them bundle together at the apex of each cone to pass into layer III. Surrounding the cones of neurons there are horizontally aligned, thin dendrites. The location of these dendrites coincides with the dark walls of the honeycomb pattern seen in layer IVA after cytochrome oxidase reactions, or after the parvocellular input from the lateral geniculate nucleus has been labeled. Thus the cones of pyramidal cells within upper layer IV fit into the pockets of the honeycomb pattern. Below the cones of pyramidal cells are the outer Meynert cells within layer IVB, and the cell bodies of these large neurons are disposed so that they preferentially lie beneath the neuropil between the cones of pyramids.It is suggested that pyramidal cell modules are a basic feature of the cerebral cortex, and that these are combined together by afferent inputs to the cortex to generate the systems of functional columns.
Ultrastructural localization of substance P, met‐enkephalin, and somatostatin immunoreactivity in lamina X of the primate spinal cord
Authors: Lamotte Carole C. , Shapiro Christine M. 
Published: January 2005

AbstractThe ultrastructural localization of substance P (SP), met‐enkephalin (MENK), and somatostatin (SS) in the lamina X area surrounding the central canal of the macaque monkey was examined by the indirect peroxidase‐antiperoxidase method. The most common synaptic terminals in lamina X were simple terminals (S) with small rounded or pleomorphic clear vesicles: one to two dense‐core vesicles were occasionally also present. These were found on soma, dendrites, and dendritic spines, in all regions of lamina X. A second class of terminal with round or oval clear vesicles was glomerular (G) in shape, with scalloped edges, and contained many mitochondria. These large terminals had several synaptic contacts onto dendrites, spines, and small terminals and were found mainly in the lateral region. The third class (L) contained small clear vesicles and several vesicles with large, dense cores (100–125 nm), and also contacted dendrites, mainly lateral to the canal. The fourth class of terminal (D) contained small clear vesicles and several vesicles with small, dense cores (75–100 nm): these contacted dendrites and somata in all areas. Very few terminals with fiat vesicles were identified. There was an unequal distribution of immunoreactivity among the several terminal classes identified in lamina X. Most SP terminals were S terminals, but SP L terminals were also common: few were D terminals. MENK terminals were usually either S terminals or D terminals: L terminals were rarely MENK positive. SS terminals were commonly D terminals or S terminals: L terminals were also rarely SS positive. Only SP terminals were identified as G terminals. Synaptic targets of SP, MENK, and SS terminals were most commonly dendrites. In addition to unlabelled neurons, peptidergic neurons and their processes were also synaptic targets of terminals containing the same peptide. The distributions of these peptides in primate lamina X differ from that of the same peptides in primate superficial dorsal horn. These differences are important, in consideration of some of the parallels that may be drawn between the lamina X area and the superficial dorsal horn: both areas have high concentrations of the same peptides, receive nociceptive primary afferents, and contain spinothalamic and other projection neurons. Nevertheless, comparison of the distribution of immunoreactivity among terminal classes indicates that neurochemical organization at the ultrastructural level is quite distinct in each of the two areas. This may also reflect other roles of the lamina X area, including its involvement in visceral functions, although it would be expected that this element might be less prominent at the cervical levels we investigated.
Dendritic morphology of pyramidal neurones of the visual cortex of the rat: I. Branching patterns
Authors: Larkman Alan U. 
Published: January 2005

AbstractThe aim of this study was to provide quantitative descriptions of the branching patterns of basal and apical dendrites of pyramidal neurones from the visual cortex of the rat. Thirty‐nine neurones from cortical layers 2/3 and 5, that had been injected with horseradish peroxidase, reconstructed, and measured with the light microscope as part of an earlier study (Larkman and Mason, '90; J. Neurosci. 10:1407–1414), were used. The cells had previously been divided into three classes, layer 2/3 cells and thick and slender layer 5 cells, on the basis of their dendritic morphology.The branching pattern of the basal and apical oblique dendrites was similar for all the cells. Between 3 and 9 basal trees arose from the soma and the number of tips in each tree varied widely, between 1 and 13. The path lengths of all the basal dendrites of a given cell were relatively constant, however. Most basal dendritic branching occurred close to the soma, such that terminal segments were much longer than intermediate segments and contributed approximately 90% of the total dendritic length of each tree. Terminal segments showed only a narrow range of diameters. Most apical oblique trees arose from the proximal part of the apical trunk. They tended to be less highly branched but were otherwise extremely similar to basal trees. Distal oblique trees were unbranched or branched only once, and their terminal segments tended to be shorter and thinner than those of basal trees.The branching pattern of the apical terminal arbors was different, with many longer intermediate segments. The terminal segments tended to be thinner than those of basal or proximal oblique trees. Slender layer 5 cells were without obvious terminal arbors.The basal and proximal oblique dendrites jointly sampled a roughly spherical volume of cortex centred about the soma, and together they accounted for the substantial majority of the cell's total dendritic shaft membrane area. Comparisons with previous studies suggest that intracellular HRP injection can yield a more complete visualization of dendritic morphology than is obtained using Golgi‐based methods (unless cells are reconstructed across tissue slabs), and can therefore result in a different view of the relative importance of the various components that make up the cell's dendritic system.
Reorganization of the area dentata serotoninergic plexus after lesions of the median raphe nucleus
Authors: Haring John H. 
Published: January 2005

AbstractSerotoninergic projections from the dorsal and median raphe nuclei to the area dentata of the hippocampal formation terminate mainly in the molecular layer and hilus, respectively. Consequently, a reduction in the density of the hilar serotoninergic plexus is seen by immunocytochemistry 2 weeks after lesions of the median raphe nucleus. Hippocampal serotonin concentration and serotonin high affinity uptake are also significantly reduced. Six weeks after lesion, surviving serotoninergic axons form a dense band in the inner molecular layer of the dorsal area dentata, a region that usually contains a sparse serotoninergic plexus. Moreover, serotoninergic fibers traverse the molecular layer and pass through the granule cell layer to reinnervate the hilus. Serotonin concentration and high affinity uptake have recovered to near normal levels by 6 weeks postlesion. Changes in the anatomical distribution of the area dentata serotoninergic plexus have not been reported in cases in which serotoninergic sprouting follows axotomy of serotoninergic projections. Thus direct lesions of serotoninergic neurons can produce a homotypic compensatory response that is qualitatively different from that generated by axotomy. The mechanistic basis for this reorganization is unclear, but the apparent extension of serotoninergic axon collaterals toward the hilus suggests that the denervated hilar neuropil is guiding reinnervation. Finally, anatomical evidence from animals studied 10 weeks postlesion suggests that the compensatory proliferation of serotoninergic axons observed 6 weeks after median raphe lesion is a transient event.
Further evidence of extrinsic forces in bending of the neural plate
Authors: Smith Jodi L. , Schoenwolf Gary C. 
Published: January 2005

AbstractBending of the neural plate has long been considered to be driven by principally intrinsic forces generated by wedging of neurepithelial cells. Our previous studies have shown that during neural fold elevation, significant neurepithelial cell wedging occurs only within the median hinge point (MHP), the midline region of neural plate anchored to the notochord. We have also shown that neural fold elevation can still occur when MHP cells are prevented from becoming wedge‐shaped but fails to occur when the neural plate is separated from lateral nonneurepithelial tissues, even though MHP cells still become wedge‐shaped and the midline neural plate still furrows. Together, these results suggest that neural fold elevation, rather than being driven by neurepithelial cell wedging, is driven, at least in part, by extrinsic forces generated by lateral nonneurepithelial tissues. However, it could be argued that in the absence of localized neurepithelial cell wedging, compensatory and atypical cell wedging occurred uniformly throughout the neural plate, providing forces adequate for neural fold elevation. Likewise, it could be argued that in the process of separating the neural plate from lateral nonneurepithelial tissues, the neural plate was damaged to the extent that the neural folds were unable to elevate. To investigate the validity of these arguments, we removed the following tissues microsurgically prior to neural fold elevation: MHP cells, varying amounts of lateral neurepithelial cells (L cells), and the tissues directly underlying these two populations of neurepithelial cells. We found that the neural folds still formed and underwent elevation, convergence, and fusion, resulting in an essentially normal neural tube, even though MHP cells, the underlying notochord, and some L cells were absent for long craniocaudal distances. These results demonstrate that microsurgery alone does not damage the neural plate sufficiently to prevent neural fold elevation, convergence, and fusion. Moreover, the fact that each of the two persisting remnants of lateral neurepithelium generally remained straight and consistently changed their orientation from horizontal to vertical rather than curling suggests very strongly that bending of the neural plate in these embryos is not the result of compensatory and atypical cell wedging. Finally, the results provide further direct evidence of extrinsic forces in bending because the two remnants of lateral neurepithelium, which were oriented horizontally at the time of tissue extirpation, could not have become oriented vertically in the absence of such forces.
Development and migration of avian sympathetic preganglionic neurons
Authors: Prasad Anita , Hollyday Margaret 
Published: January 2005

AbstractModern neuronanatomical techniques were used to investigate the development of the avian sympathetic preganglionic cell column in the spinal cord of the chick embryo. [3H]thymidine autoradiography indicated that the majority of these preganglionic, or “Terni column” neurons are generated between stages 18 and 24 (days 2–4). This coincides with the genesis of the somatic motoneurons in the thoracic levels of the cord, and therefore differences in the time of origin cannot explain the divergent fates of these two neuronal populations. Data obtained from short‐survival autoradiographic experiments indicated that many early born cells remain close to the ventral region of the ventricular epithelium until day 5 of incubation. Ventral root injections used to label retrogradely neurons projecting an axon into the ventral root (Terni cells and somatic motoneurons) have labeled neurons next to the ventricular epithelium at the same early stages. Thus, it seems likely that some Terni cells, if not all, maintain medial positions and do not migrate laterally to join a common motor column before initiating a dorsal migration. Analysis of a closely staged series of embryos, whose Terni column neurons were retrogradely labeled with wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP), revealed that between days 5 and 8 of incubation, Terni column neurons migrated dorsally to attain their adult position adjacent to the central canal. These changes in position were reflected in the changing morphology of the Terni column neurons, visualized by the Golgi‐like HRP labeling. The positions of the migrating Terni cells differed from those of commissural cells, indicating that these fibers are not the substrate for the dorsal migration. The dorsal migration of Terni column cells was not disrupted by the surgical removal of the sympathetic ganglia, the synaptic targets of these neurons, nor by disruption of spinal afferents. Taken together, these results suggest that the migratory behavior of Terni cells is distinctive when compared to that of somatic motoneurons, and that local and/or intrinsic cues within the spinal cord guide the dorsal migration of Terni column cells.
Morphology and frequency of axon terminals on the somata, proximal dendrites, and distal dendrites of dorsal neck motoneurons in the cat
Authors: Rose P. K. , Neuber‐Hess M. 
Published: January 2005

AbstractThe purpose of the present study was to compare the frequency of different classes of axon terminals on selected regions of the somatodendritic surface of dorsal neck motoneurons. Single motoneurons supplying neck extensor muscles were antidromically identified and intracellularly stained with horseradish peroxidase. By using light microscopic reconstructions as a guide, axon terminals on the somata, proximal dendrites (within 250 μm of the soma), and distal dendrites (more than 540 μm from the soma) were examined at the electron microscopic level.Axon terminals were divided into several classes based on the shape, density, and distribution of their synaptic vesicles. The proportion of axon terminals belonging to each axon terminal class was similar on the somata and proximal dendrites. However, there were major shifts in the relative frequency of most classes of axon terminals on the distal dendrites. The most common classes of axon terminals on the somata and proximal dendrites contained clumps of either spherical or pleomorphic vesicles. These types of axon terminals accounted for more than 60% of the axon terminals on these regions. In contrast, only 11% of the axon terminals found on distal dendrites belonged to these types of axon terminals. The most commonly encountered axon terminal on distal dendrites contained a dense collection of uniformly distributed spherical vesicles. These types of axon terminals accounted for 40% of all terminals on the distal dendrites, but only 5–7% of the axon terminals on the somata and proximal dendrites. Total synaptic density on each of the three regions examined was similar. However, the percentage of membrane in contract with axon terminals was approximately four times smaller on distal dendrites than somata or proximal dendrites. Axon terminals (regardless of type) were usually larger on somata and proximal dendrites than distal dendrites.These results indicate that there are major differences in the types and arrangement of axon terminals on the proximal and distal regions of dorsal neck motoneurons and suggest that afferents from different sources may preferentially contact proximal or distal regions of the dendritic trees of these cells.
Estrogen influences on oxytocin mRNA expression in preoptic and anterior hypothalamic regions studied by in situ hybridization
Authors: Chung Sookja K. , McCabe Joseph T. , Pfaff Donald W. 
Published: January 2005

AbstractPossible estrogen influences on oxytocin mRNA expression were studied in preoptic and anterior hypothalamic regions as might be important for behavioral as well as neuroendocrine controls. In situ hybridization for oxytocin mRNA determination was supported by immunocytochemical identification and was compared with vasopressin mRNA in situ hybridization. With these techniques, oxytocin‐expressing neurons were identified in medial preoptic, anterior commissural, periventricular, paraventricular, supraoptic, and perifornical nuclei as well as the bed nucleus of the stria terminalis and intersupraopticoparaventricular (internuclear) islands. Distribution and number of oxytocin mRNA‐containing neurons and oxytocin mRNA levels were compared between ovariectomized control rats given cholesterol implants and ovariectomized rats given short‐term (2 days) or long‐term (2 months) estradiol treatment (10% estradiol, subcutaneous silastic implants). Effectiveness of long‐term estrogen treatment was confirmed behaviorally. While there was a trend in several cell groups for a larger number of oxytocin‐mRNA‐containing neurons to be observed following 2 days of estrogen treatment, this was not statistically significant. Moreover, additional oxytocin‐mRNA containing cell groups were not seen after short or long estradiol treatment. With computer‐aided analysis, mean pixels per oxytocin‐mRNA expressing neuron (reflecting oxytocin mRNA content) were compared between groups: In the supraoptic nucleus and the anterior commissural nucleus, these were increased both by 2 days and 2 months of estradiol treatment. These differences may be important in modulating female reproductive behavior. Present findings also suggest that estradiol can affect the oxytocinergic system via an indirect route since the cell groups influenced here by estradiol do not contain estrogen receptors. Oxytocinergic neurons may serve as a good system to compare direct transcriptional with indirect effects of hormones.
Brain sites projecting to the spinal nucleus of the bulbocavernosus
Authors: Monaghan Edward P. , Breedlove S. Marc 
Published: January 2005

AbstractMotoneurons of the spinal, nucleus of the bulbocavernosus (SNB) occupy a distinct dorsomedial position in the ventral horn of lumbar segments 5 and 6 and innervate sexually dimorphic striated muscles of the rat perineum, including the bulbocavernosus and levator ani. To begin the study of brain influences upon SNB function, we used retrograde tracers to identify brain regions that project to the area of SNB motoneurons. Our findings provide strong evidence that lateral vestibular and several reticular nuclei innervate the SNB. Additional possible afferents include the superior and medial vestibular nuclei raphe nucleus, red nucleus, interstitial nucleus of the medial longitudinal fasciculus, and paraventricular nucleus.