bluuebunny/crossref_metadata_2025_split huggingface dataset:
β‐Endorphin/ACTH immunocytochemistry in the CNS of the lizard Anolis carolinensis: Evidence for a major mesencephalic cell group
Authors: Khachaturian Henry , Dores Robert M. , Watson Stanley J. , Akil Huda 
Published: January 2005

AbstractThe immunocytochemical distribution of β‐endorphin and other proopiomelanocortin (POMC) peptides in the central nervous system of the lizard Anolis carolinensis was determined. Colchicine pretreatment was used to enhance perikaryal immunoreactivity. A major finding of this study is the localization of a previously undetected mesencephalic cell group which exhibits immunoreactivity to β‐endorphin, ACTH, and α‐MSH. The perikarya of these neurons are large, bipolar, and situated in the mesencephalic tegmental area. They appear to project to the mesencephalic central gray and other brainstem structures. In contrast, the immunoreactive parvicellular perikarya of the medial‐basal hypothalamus, corresponding to the POMC perikarya of the rodent arcuate nucleus, exhibit major rostral projections to various telencephalic and diencephalic structures. The exact extent of fiber projections and innervation patterns arising from either of these two groups is not clear at this time and will require further analyses. Scattered fiber immunoreactivity was also seen in the medial cerebral cortex and the striatal complex, regions which apparently are not innervated by β‐endorphin fibers in the rodent brain. Also, no immunoreactivity was seen to an antiserum to the 16K peptide of POMC. Other similarities and differences in the brain distribution of POMC in reptiles and mammals are discussed.
Cortical projections to the superior colliculus in the macaque monkey: A retrograde study using horseradish peroxidase
Authors: Fries W. 
Published: January 2005

AbstractThe topical and laminar distribution of corticotectal cells, as well as their size and morphology, were studied in the macaque monkey with the horseradish peroxidase (HRP) technique. After HRP injections restricted primarily to the superficial layers of the colliculus, labelled cells were found in visual cortex (areas 17, 18, and 19) and both in the frontal eye field (area 8) and the adjacent part of premotor cortex (area 6). The clustering of labelled cells in visual cortex indicated that each of the anatomically and functionally distinct visual areas has its own set of collicular projections. When intermediate and deeper layers of the colliculus were injected, labelled cells were found also in posterior parietal cortex (area 7) where they were concentrated mainly on the posterior bank of the intraparietal fissure, in inferotemporal cortex (areas 20 and 21), in auditory cortex (area 22), in the somatosensory representation SII (anterior bank of sylvian fissure, area 2), in upper insular cortex (area 14), in motor cortex (area 4), in premotor cortex (area 6), and in prefrontal cortex (area 9). In the motor and premotor cortex, labelled cells formed a continuous band which appeared to stretch across finger‐hand‐arm‐shoulder‐neck representation. Similarly, the cluster of labelled cells in area 2 may correspond to the finger‐hand representation of SII. The cortical regions not containing labelled cells were the somatosensory representation SI (areas 3, 1 and 2) and the infraorbital cortex.Labelled cells were restricted to layer V of all cortical areas except in the primary visual cortex, where labelled cells were found in both layer V and layer VI. The size spectrum of corticotectal cells ranged from 14.8 μm (average diameter) in area 17 to 27.8 μm in area 6, comprising cells as small as 8 μm and as large as 45 μm. Labelled cells in posterior parietal (area 7), in auditory (area 22), and in motor cortex (area 4) were small and distributed over only a narrow range of sizes. Those in premotor cortex (area 6) were often large and had a wide range in size distribution. The differences in size and morphology of corticotectal neurons suggest that they do not form a uniform class of neurons.
Role of nerve growth factor in the adult dorsal root ganglia neuron and its response to injury
Authors: Rich Keith M. , Yip Henry K. , Osborne Patricia A. , Schmidt Robert E. , Johnson Eugene M. 
Published: January 2005

AbstractThe response of dorsal root ganglia (DRG) neurons to NGF deprivation and to axotomy was examined in adult guinea pigs. The success of NGF deprivation by means of an autoimmune approach was monitored by the measurement of serum antibody titer levels against guinea pig NGF with the standard bioassay for NGF activity. That the antibody produced NGF deprivation was confirmed by histologic evidence of neuronal atrophy and apparent cell loss in sections of the superior cervical ganglia (SCG) and by marked decreases (65–80%) of SCG neurotransmitter‐synthesizing enzyme activity levels. By using the autoimmune approach a new source of guinea pigs was found which consistently produced high titers of cross‐reacting anti‐NGF antibodies.Experiments were designed to examine the response of the sensory neuron to injury while chronically deprived of NGF. Total neuronal counts in the sixth lumbar DRG 98 days after sciatic nerve crush showed no difference between NGF‐deprived and control ganglia. Measurement of the size spectrum of DRG neurons showed evidence of atrophy of the NGF‐deprived neurons in both the uninjured and axotomized side compared to respective controls. The mean volume of uninjured sensory neurons measured in the NGF‐deprived guinea pigs was decreased 27.7% (P <0.05) compared with that of control guinea pigs.The degree of regeneration 6 days following a nerve crush was the same in NGF‐deprived sensory neurons and in controls when measured by the “pinch test” and by isotope‐labeled axonal transport studies. The long‐term regenerative response was analyzed with various histologic and morphometric techniques studying the sural nerve 98 days after sciatic nerve crush. No differences between control and NGF‐deprived guinea pig sural nerves were noted at the light microscopic and ultrastructural levels. These studies demonstrated an unimpaired regenerative capability of sensory neurons deprived of NGF compared with controls.
Morphology of Golgi‐Cox‐impregnated barrel neurons in rat SmI cortex
Authors: Simons Daniel J. , Woolsey Thomas A. 
Published: January 2005

AbstractGolgi‐Cox‐impregnated neurons in the barrel cortex of the rat were studied qualitatively and quantitatively. Adult rat brains were sectioned perpendicular to or parallel to the cortical representation of the large facial vibrissae at 125 μm. Cortical laminar and barrel boundaries were identified from the Nissl counterstain. Over 200 well‐impregnated neurons in cortical layers I–IV were selected for classification and further detailed study. Three broad classes of neurons were recognized: (1) pyramidal cells with conical somata, a stout apical dendrite, and spines; (2) class I nonpyramidal cells having small spherical somata and spiny dendrites; and (3) class II nonpyramidal cells having larger ellipsoid somata and smooth or beaded dendrites. The class I cells were further subdivided into “star pyramids” (cells with an apical dendrite) and spiny stellate cells (cells in which all dendrites were of similar length). The class II cells also were subdivided into multiform cells (with multiple dendrites radiating from the soma) and bipolar cells (with two principal dendritic trunks arising from the superficial and deep aspects of the soma). The position of these various cell types in the superficial cortical laminae was mapped in sections normal to the pia. Numerous examples of the class I and class II neurons were drawn with respect to the barrels in layer IV and the extent of their processes noted. Finally, approximately 250 barrel‐related class I and II neurons were studied quantitatively using a computer‐microscope and digitizing tablet.The density of the Golgi‐impregnated neurons corresponds to the pattern of cell density seen with the Nissl counterstain. The various cell types arc not uniformly distributed as a function of cortical depth. Cells with apical dendrites were found principally in the supragranular layers and star pyramids in the superficial one‐half of layer IV. Spiny stellate cells are concentrated in layer IV and the smooth cells are present in greatest number in deep layer III and deeper layer IV. On the basis of these distributions we suggest that layer IV be subdivided into two sublaminae. The class I and class II neurons can be distinguished according to quantitative criteria which apply in either plane of section used. Class I neurons have smaller projected somal areas, more proximal dendritic branching, and shorter dendrites when class I and II neurons are measured in three dimensions. For neurons with somata in layer IV there is a pronounced tendency for the dendrites to be confined to one or two cortical barrels depending on the exact location of the soma in a barrel. This finding is true for both the class I and class II cells although the class I neurons had more tightly confined processes, particularly with respect to the vertical axis of the cortex. These results are discussed in relation to similar findings in mice and to functional studies of the rodent barrel cortex.
Development of synaptic organization in the tangential vestibular nucleus: A quantitative electron microscope study
Authors: Peusner Kenna D. 
Published: January 2005

AbstractThe objective of the present study is to quantify the developmental changes in the total synaptic pattern of one part, the soma, of one particular cell type, the principal cells of the tangential vestibular nucleus. The term “synaptic space” is defined and quantified. Intermediate stages in the development of synaptic organization are compared.The findings show that the synaptic space available to the full complement of afferents is constant throughout development, while specific terminals in the afferent population change their synaptic space allotments. The synaptic‐junction covering is invariant for small terminals at intermediate stages of development with set proportions between “active” and “non‐active” zones of the synaptic surfaces. However, the spoon endings and the postsynaptic target cells are covered by synaptic junctions in variable amounts.The findings are important to the fields of neuroembryology and neural plasticity, for the system provides a useful basis to measure the influence of factors in the local environment and the role of formation of synaptic connections in the competition for synaptic space. This study will assist investigators to probe the mechanisms operating in the selection of competing afferents for the limited amount of surface area available under the changing conditions of maturation and aging in the central nervous system.
The distribution of filipin‐sterol complexes in photoreceptor synaptic membranes
Authors: Cooper Nigel G. F. , McLaughlin Barbara J. 
Published: January 2005

AbstractThe polyene antibiotic filipin, which binds to membrane sterols, has been used to investigate the relative distribution of cholesterol at photoreceptor synaptic junctions in the chick retina. Following anesthesia and aldehyde perfusion fixation, the retina is removed and immersed in fixative solution containing the filipin for 36–48 hours. The retinas are then processed for freeze‐fracture. Electron microscopy of freeze‐fracture replicas demonstrates that the filipin‐sterol complexes are not evident between intramembrane particles of the presynaptic and postsynaptic particle arrays that are present at ribbon and basal junctions. In contrast, the synaptic vesicle fusion zone of ribbon junctions contains large numbers of filipin‐sterol complexes which are observed merging with the free margins of the presynaptic particle array. There is a scarcity of such complexes, however, around the free margins of basal junction presynaptic particle arrays. These latter sites do not contain a vesicle fusion zone. Particle‐poor areas of membrane that surround postsynaptic particles arrays of ribbon and basal junctions also do not contain filipin binding sites. The nonsynaptic membrane of photoreceptor terminals contains large numbers of filipin‐sterol complexes, less tightly packed than in the synaptic vesicle fusion zone. Coated vesicle fusion sites in the presynaptic membrane contain groups of intramembrane particles but the filipin‐sterol complexes are excluded from these sites. The observations suggest that synaptic membrane domains which interact with cytoskeletal components, such as clathrin and pre‐ and postsynaptic densities contain less cholesterol than other domains such as the synaptic vesicle fusion zones.
Prenatal and postnatal development of retinogeniculate and retinocollicular projections in the mouse
Authors: Godement Pierre , Salaün Josselyne , Imbert Michel 
Published: January 2005

AbstractThe development of retinal projections to the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) has been studied in fetal and neonatal mice of the pigmented C57BL/6 strain, using the anterograde transport of tritiated proline and horseradish peroxidase (HRP).Retinal efferents are present contralaterally just beyond the chiasm at E14. By E16 they have grown into both dLGN and SC. Ipsilateral fibers are limited to the proximal optic tract at E16; their growth into dLGN and SC is delayed until E18‐birth.During the first 2 postnatal days, an early population of ipsilateral fibers invades the dLGN. Most of these fibers grow in or around the mediodorsal sector of the dLGN, i.e., the future binocular segment. Fibers are also present, but at lower densities, in the ventral half of the nucleus and thereafter become dispersed or are lost, without at any stage becoming dense. Some denser labeling is also present ipsilaterally in the outer rim of dLGN, just below the optic tract, and later disappears.On the third postnatal day, the ipsilateral fibers establish a deep and denser projection along the medial and dorsal borders of dLGN; this projection overlaps part of the crossed projection, which at this age extends to the whole nucleus. The segregation of each projection starts on the fourth postnatal day, when crossed fibers begin to disappear from the small region of uncrossed projection. This process goes on for another 4 days. During this period, the ipsilateral fibers withdraw from the deepest layer of dLGN, and their terminal density increases gradually; by the eighth postnatal day, both projections are already well separated.Dense crossed projections first appear near the surface of the SC at birth. Prior to this, retinal fibers course throughout neurons of the collicular plate and underneath the pia.The uncrossed fibers invade the SC between birth and P3. They are located preferentially in the anterior and medial aspect of the SC. Subsequently, there occurs a diminution in the laminar and tangential extent of these projections, simultaneously with an intensification of the ipsilateral input to several small, longitudinally oriented clusters located deep to the crossed projections.
Ganglion cells in retinae transplanted to newborn rats
Authors: Perry V. H. , Lund R. D. , McLoon S. C. 
Published: January 2005

AbstractCells projecting out of retinal transplants placed over the tectum of newborn rats were studied by labelling with horseradish peroxidase 1 month or more after transplantation. Using this technique, it was found that only cells with the dendritic characteristics of ganglion cells were labelled and, furthermore, that the major classes of ganglion cells seen in normal retinae were also present in the transplants. The cell body size histograms of ganglion cells in normal and transplanted retinae compared closely with each other.Dendritic trees were closely confined by the limits of the inner plexiform layer, and if that layer was folded or distorted, they were themselves frequently abnormal. While axons usually coursed over the surface of the retinal transplants, they quite often followed an anomalous course crossing the individual layers.It appears, therefore, that this transplantation procedure has relatively little impact on the ability of ganglion cells to develop many of their characteristic morphological features. Whether the different functional responses of the various ganglion cell classes are also preserved after transplantation is a matter for further investigation.
The development of the nucleus isthmi in Xenopus laevis. I. Cell genesis and the formation of connections with the tectum
Authors: Udin Susan Boymel , Fisher Mark D. 
Published: January 2005

AbstractThe nucleus isthmi (NI) of the amphibian relays visual input from one tectum to the other tectum and thus brings a visual map from the eye to the ipsilateral tectum. This isthmotectal visual map develops slowly; it is first detected electrophysiologically at stages 60–62, the age at which the eyes begin their dorsalward migration and the region of binocular overlap begins to increase in extent. During this critical period of life, normal binocular visual input is required for establishment of normal topographic isthmotectal projections. In this study, we have used anatomical methods to trace cell birth, cell death, and formation of connections by the nucleus isthmi during the critical period.Tritiated thymidine labelling demonstrates that cells in the nucleus isthmi are generated throughout most of tadpole life (stages 29–62). Most cells conform to an orderly ventrodorsal gradient starting from stage 29 and extending to stage 56; later cells are inserted at apparently random locations in the nucleus. We have re‐examined the hypothesis of Tay and Straznicky (1980) that the order of cell genesis in the NI and tectum could help establish proper isthmotectal connections, and we find that a timing mechanism does not explain the two‐dimensional topography of the isthmotectal map but that timing may aid in proper mediolateral positioning of isthmotectal axons at the points where they first enter the tectum.Horseradish peroxidase labelling was used to investigate whether anatomical projections from tectum to NI and from NI to tectum are present prior to the onset of eye migration. The results show that there are tectoisthmotectal projections by stage 52. Moreover, isthmotectal axons grow into as yet monocular tectal regions prior to the onset of eye migration. At stage 60, when binocular overlap begins, isthmotectal axons are visible throughout the tectum but are densely branched only at the rostral tectal margin, the location where they are predicted to occur on the basis of electrophysiological maps.
The onset and development of descending pathways to the spinal cord in the chick embryo
Authors: Okado Nobuo , Oppenheim Ronald W. 
Published: January 2005

AbstractThe ontogenetic development of afferent (supraspinal and propriospinal) as well as efferent (ascending) fiber connections of the spinal cord was examined following the injection of horseradish peroxidase (HRP) or wheat germ agglutinin HRP (WGA‐HRP) into the cervical and lumbar spinal cords (or brains) of embryos ranging in age from 4 to 14 days of incubation. A few cells were first reliably retrogradely labelled in the pontine reticular formation on embryonic day (E) 4 and E5 following the injection of WGA‐HRP into the cervical and lumbar spinal cord, respectively. Propriospinal projections to the lumbar spinal cord, originating from brachial spinal cord, were found by E5, and from the cervical spinal cord by E5.5. Ascending fibers arising from neurons in the lumbar spinal cord could be followed to rostral mesencephalic levels in E5 embryos. Thus, the earliest supraspinal, propriospinal, and ascending fiber connections appear to be formed almost simultaneously. Retrogradely labelled cells were found in the raphe, reticular, vestibular, interstitial, and hypothalamic nuclei in E5.5 embryos following lumbar injections of WGA‐HRP. Except for neurons in cerebellar nuclei, all the cell groups of origin that project to the cervical spinal cord of posthatching chicks were also retrogradely labelled by E8. There was a delay in the time of appearance of the projections from various regions of the brain stem to the lumbar versus the cervical spinal cord, ranging from 0.5 to 7 days, but typically of about 3 days duration. A large number of cells located in the ventral hypothalamic region, just dorsal to the optic chiasma, were found to be labelled following cervical HRP injection between E6 and E10. These cells may represent transient projections that are present only during embryonic stages since no labelled cells were found in this region in the newly‐hatched chick.
Evidence for proctolin‐like substances in the central nervous system of the leech hirudo medicinalis
Authors: Li C. , Calabrese R. L. 
Published: January 2005

AbstractThe distribution of proctolin‐like immunoreactive (PLI) cells was mapped in the central nervous system of the leech Hirudo medicinalis. In segmental ganglia, PLI cells can be divided into two groups: cells that stain repeatedly in every successive ganglion, and cells that stain only in specific segmental ganglia. The number of PLI cells, therefore, ranged from eight to 20 cells per ganglion. One bilateral pair of PLI cells (cells PLI‐1) was further characterized morphologically by Lucifer yellow and horseradish peroxidase cell injections. Cell PLI‐1 conforms in soma position, morphology, and physiological properties with cell 101, which has been previously classified as an inhibitory motoneuron to the flattener muscles.A locust bioassay (O'Shea and Adams, Science 213:567–569, 1981) was used to detect the presence of proctolin‐like bioactivity. Extracts of leech ganglia when applied to the extensor tibial is muscle of the locust leg induced a proctolin‐like response similar to the responses induced by proctolin standards. This work extends the finding of proctolin‐like substances to the annelid phylum.