bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuroarchitecture of the central complex in the brain of the locust Schistocerca gregaria and S. americana as revealed by serotonin immunocytochemistry
Authors: Homberg Uwe 
Published: January 2005

AbstractThe central complex is a prominent structure in the insect brain, yet its anatomical organization and functional role is still poorly understood. To facilitate investigations on the physiology of the central complex, this study describes its anatomical organization in the brain of locusts (Schistocerca gregaria and Schistocerca americana) based on an investigation of serotonin immunocytochemistry. Most subdivisions of the central complex including the protocerebral bridge, several layers in the upper division of the central body, and the noduli of the central body are innervated by serotonin‐immunoreactive neurons, while the lower division of the central body does not exhibit serotonin‐like immunoreactivity. Several types of serotonin‐immunoreactive neurons can be distinguished. A system of about 60 columnar neurons innervates the protocerebral bridge, layer III of the upper division of the central body, and the noduli. A group of 15–20 bilateral pairs of serotonin‐immunoreactive neurons connects the posterior optic tubercles with the protocerebral bridge. About ten pairs of neurons with somata in the inferior protocerebrum innervate layer la of the upper division of the central body. In addition, large‐field neurons arborize in layers Ia and Ib of the upper division of the central body and in the lateral accessory lobes. The detailed mapping of serotonin immunoreactivity provides further insight into the anatomical organization of the central complex and suggests that serotonin is a major neuroactive substance within this brain structure.
Morphological relationships among extensor digitorum longus, tibialis anterior, and semitendinosus motor nuclei of the cat: An investigation employing the retrograde transport of multiple fluorescent tracers
Authors: Hoover J. E. , Durkovic R. G. 
Published: January 2005

AbstractTo determine the morphological relationships among extensor digitorum longus (EDL), tibialis anterior (TA), and semitendinosus (St) motor nuclei in the spinal cord of the cat, these nuclei were retrogradely labeled with three different fluorescent tracers. The fluorochromes‐bisbenzimide, nuclear yellow, and propidium iodide‐were applied by intramuscular injection or soaking the muscle nerve. The positions of the labeled motor nuclei were bilaterally symmetrical The EDL and TA motoneurons were located in close proximity to one another, in the lateral regions of lamina IX in spinal segments L6 and L7. Although the boundaries of each nucleus were tightly opposed, the EDL and TA motor nuclei overlapped minimally, with the somata of EDL motoneurons positioned dorsal to those of TA. The St motor nucleus was located ventromedial to that of EDL and extended from the caudal portion of L6 through S1. Supplemental studies of the reflex effects evoked in EDL, TA, and St muscles by cutaneous nerve stimulation provided physiological observations that maybe related to these anatomical results.
Trigeminal primary afferent projections to “non‐trigeminal” areas of the rat central nervous system
Authors: Marfurt Carl F. , Rajchert Donna M. 
Published: January 2005

AbstractThe central projections of rat trigeminal primary afferent neurons to various “non‐trigeminal” areas of the central nervous system were examined by labeling the fibers with wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) transported anterogradely from the trigeminal ganglion. This technique produced a clear and comprehensive picture of trigeminal primary afferent connectivity that was in many ways superior to that which may be obtained by using degeneration, autoradiography. cobalt labeling, or HRP transganglionic transport techniques. Strong terminal labeling was observed in all four rostrocaudal subdivisions of the trigeminal brainstem nuclear complex, as well as in the dorsal horn of the cervical spinal cord bilaterally, numerous brainstem nuclei, and in. the cerebellum. Labeling in the ipsilateral dorsal horn of the cervical spinal cord was very dense at C1, moderately dense at C2 and C3, and sparse at C4‐C7. Numerous fibers crossed the midline in the medulla and upper cervical spinal cord and terminated in the contralateral pars caudalis and dorsal horn of the spinal cord from C1‐C5. The latter axons terminated most heavily in the mandibular and ophthalmic regions of the contralateral side. Extremely dense terminal labeling was observed in the ipsilateral paratrigeminal nucleus and the nucleus of the solitary tract, moderate labeling was seen in the supratrigeminal nucleus and in the dorsal reticular formation, and small numbers of fibers were observed in the cuneate, trigeminal motor, lateral and superior vestibular nuclei, and in the cerebellum. The tatter fibers entered the cerebellum in the superior cerebellar peduncle and projected to the posterior and anterior lobes as well as to the interposed and lateral deep cerebellar nuclei. Most projections in this study originated from fibers in the dorsal part of the spinal tract of V, suggesting a predominantly mandibular origin for these fibers. Projections from the ophthalmic and maxillary divisions, in contrast, were directed mainly to the cervical spinal cord bilaterally, to contralateral pars caudalis, and to certain areas of the reticular formation. In conclusion, this study has demonstrated that somatosensory information from the head and face may be transmitted directly to widespread and functionally heterogeneous areas of the rat central nervous system, including the spinal cord dorsal horn, numerous brainstem nuclei, and the cerebellum. These projections may play important roles in trigeminospinal reflexes (dorsal horn of spinal cord C1‐C7), fusion of the sensory maps of the right and left sides of the head (contralateral projections), trigeminovisceral integration (paratrigeminal and solitary), control and integration of oral motor behavior (supratrigeminal and motor V), orofacial reflexes (reticular formation), and the coordination and stabilization of head posture and gaze (cuneate, vestibular, and cerebellum).
Midget ganglion cells of the parafovea of the human retina: A Study by electron microscopy and serial section reconstructions
Authors: Kolb Helga , Dekorver Laura 
Published: January 2005

AbstractIn this study we used serial section electron microscopy and three‐dimensional reconstructions to examine four midget ganglion cells of the human retina. The four cells were located in the parafoveal retina 2.5 mm or 8° from the foveal center. Both type a (with dendritic trees in distal inner plexiform layer) and type b (with dendritic trees in proximal inner plexiform layer) midget ganglion cells have been studied. These culls have dendritic trees of 7–9 μm diameter, and their complete dendritic trees in the neuropil of the inner plexiform layer can be analyzed, as well as the bipolar cell axon terminals having synaptic input, by a study of 100–150 serial ultrathin sections. Type a midget ganglion cells appear to be in a one‐to‐one relationship with fiat midget bipolar cell axon terminals ending in distal inner plexiform layer. Type b midget ganglion cells are in a one‐to‐one synaptic relationship with invaginating midget bipolar cell axon terminals in proximal inner plexiform layer. The midget bipolar cells primarily involved with the midget ganglion cells do not contact other ganglion cell dendrites. In other words, midget bipolar cells appear to be in exclusive contact with single midget ganglion cells in the human retina.The midget ganglion cells receive most of their input from their associated midget bipolar cells in the form of ribbon synapses at dyads or monads (55–81 ribbons total), although ribbonless synapses are seen occasionally. In all four midget ganglion cells reconstructed, one or two other bipolar cell axon terminals, presumed to be from wide‐field bipolar types, provide 1–3 ribbon synapses each. The number of amacrine synapses upon a midget ganglion cell's dendritic tree is approximately equal to the number of bipolar ribbon inputs (43%–56% bipolar ribbons: 44%–57% amacrine synapses).We assume from our knowledge of response characteristics of ganglion cells in other mammalian retinas (Nelson et al., '78: J. Neurophysiol. 41:427–483), that the type a midget ganglion cell and its exclusive connectivity with a flat midget bipolar cell forms a single cone connected OFF‐center pathway, whereas the type b midget ganglion cell with its exclusive connectivity to an invaginating midget bipolar cell forms a single cone connected ON‐center pathway, through the retina to the brain.
Subgroup of alpha ganglion cells in the adult cat retina is immunoreactive for somatostatin
Authors: White C. A. , Chalupa L. M. 
Published: January 2005

AbstractWe have previously shown that two types of cells in the ganglion cell layer of the adult cat retina are immunoreactive for somatostatin (White et al., '90). One of the types was identified by morphological criteria as a wide‐field amacrine cell. The other cell type had a large, angular soma that resembled the alpha ganglion cell, but evidence was not available to identify it definitively as a ganglion cell. Both cell types were distributed preferentially in the inferior retina. In this report, we demonstrate that the two types of cell are, indeed, displaced amacrine cells and alpha ganglion cells. First, when retrograde tracers were injected into central visual targets, the immunoreactive large cells but not the displaced amacrine cells were found to be labeled. Second, after unilateral section of the optic nerve, the immunoreactive large cells disappeared from the retina on the lesioned side, but the displaced amacrine cells occurred in the same numbers in both retinae. In the periphery, the large cells ranged in diameter from 33 to 47 μm, comparable only to alpha ganglion cells (Boycott and Wässle, '74). An antiserum to parvalbumin was used to visualize the dendrites (Röhrenbeck and Wässle, '88) of somatostatin‐immunoreactive large cells. Based on dendritic stratification within the inner plexiform layer (Famiglietti and Kolb, '76), the somatostatin‐immunoreactive large cells were found to include both on‐center cells and off‐center cells, but were predominantly of the off‐center type. Within a local region, they were found to be arrayed with greater regularity than the overall population of alpha ganglion cells. These results indicate that alpha ganglion cells of the cat retina can be subdivided on the basis of their immunoreactive staining for somatostatin and suggest that the diversity of ganglion cells in the cat retina may be greater than has been recognized on the basis of morphological criteria alone.
Variation in terminal morphology and presynaptic inhibition at crustacean neuromuscular junctions
Authors: Tse F. W. , Marin L. , Jahromi S. S. , Atwood H. L. 
Published: January 2005

AbstractSynaptic terminals of excitatory and inhibitory neurons supplying muscle fibers in leg muscles of crabs (Pachygrapsus crassipes and Hyas areneus) were investigated with light and electron microscopy. Terminals responsible for large excitatory postsynaptic potentials (EP‐SPs) at low frequencies of activation had a compact configuration with clusters of terminal boutons radiating from the main axon branch. Terminals responsible for small EPSPs had a more diffuse organization, with boutons often arranged in series along thin axon branches. Inhibitory neurons, when activated, produced both presynaptic and postsynaptic inhibitory effects, with the former being more potent at low frequencies of activation. Presynaptic inhibition was variable in magnitude but was generally strong in fibers with large EPSPs. Representative terminals from regions of strong and weak presynaptic inhibition were identified by activity‐dependent uptake of horseradish peroxidase, serially sectioned, and reconstructed from electron micrographs. Both regions were found to contain axo‐axonal synapses from inhibitory to excitatory terminals, with a larger number in the region of strong presynaptic inhibition. In addition, axo‐axonal synapses were more uniformly distributed in the latter region. The number of inhibitory presynaptic dense bars (active zones) was somewhat higher in the region of weak inhibition, but larger individual dense bars occurred in the region of strong inhibition. Possible factors contributing to the differences in strength of inhibition include: (1) morphology and electrical properties of terminals; and (2) high probability of transmission at a relatively small number of inhibitory synapses during low frequency activation in the region of strong inhibition.
Myelin‐axon relationships established by rat vagal Schwann cells deep to the brainstem surface
Authors: Fraher John P. , Rossiter John P. 
Published: January 2005

AbstractThe central‐peripheral transitional zones of rat dorsolateral vagal rootlets are highly complex. Peripheral nervous tissue extends centrally for up to several hundred micrometers deep to the brainstem surface along these rootlets. In some instances this peripheral nervous tissue lacks continuity with the peripheral nervous, system (PNS) and so forms an island within the central nervous system (CNS). In conformity with the resulting complexity of the CNS‐PNS interface, segments of vagal axons lying deep to the brainstem surface are myelinated by one or more intercalated Schwann cells, contained in peripheral tissue insertions or islands, at either end of which they traverse an astroglial barrier. Intercalated Schwann cells are thus isolated from contact or contiguity with the Schwann cells of the PNS generally. They are short, having a mean internodal length of around 60% of that of the most proximal Schwann cells of the PNS proper, which lie immediately distal to the CNS‐PNS interface and which are termed transitional Schwann cells. The thickness of the myelin sheaths produced by intercalated Schwann cells is intermediate between that of transitional Schwann cells and that of oligodendrocytes myelinating vagal axons of the same calibre distribution. This is not due to limited blood supply or to insufficient numbers of intercalated Schwann cells, the density of which is greater than that of transitional Schwann cells. These factors are unlikely to restrict expression of their myelinogenic potential. Nevertheless, the regression data show that the setting of the myelin‐axon relationship differs significantly between the two categories of Schwann cell. Thus, the myelinogenic response of Schwann cells to stimuli emanating from the same axons may differ between levels along one and the same nerve bundle. Mean myelin periodicity was found to differ between sheaths produced by intercalated and by transitional Schwann cells.
Naturally occurring cell death in the developing dentate gyrus of the rat
Authors: Gould Elizabeth , Woolley Catherine S. , McEwen Bruce S. 
Published: January 2005

AbstractThe rat dentate gyrus is a unique brain structure in that most of its neurons are born postnatally. Cell death is known to be an important phenomenon in brain development and yet it is at present unknown whether the dentate gyrus undergoes a period of naturally occurring cell death. In order to determine whether or not cell death plays a role in the development of the dentate gyrus, we examined the density of degenerating cells and healthy cells in the suprapyramidal and infrapyramidal granule cell blades and the hilus during the postnatal period. Light microscopic examination of Nissl‐stained brain tissue revealed substantial numbers of pyknotic cells throughout the dentate gyrus during the first postnatal week. Quantitative analysis of the suprapyramidal blade showed a peak in the density of pyknotic cells at the end of the first postnatal week. This peak in the density of degenerating cells coincided with a significant decrease in the density of healthy cells in this region. No rostrocaudal gradient in cell death was observed for the suprapyramidal blade. However, cell death in the suprapyramidal blade proceeded along superficial to deep as well as lateral to medial gradients.Within the infrapyramidal blade/hilus, cell death occurred at different times depending on the rostrocaudal level of the dentate gyrus. Peak density of pyknotic cells was observed the day after birth in the rostral part of the infrapyramidal blade/hilus while pyknosis did not reach a peak in the middle and temporal thirds of this region until the end of the first postnatal week. Cell death in the infrapyramidal blade proceeded in a superficial to deep and lateral to medial direction. These results indicate that the dentate gyrus undergoes a significant period of naturally occurring cell death during the early postnatal period.
Labeling and distribution of AII amacrine cells in the rabbit retina
Authors: Mills Stephen L. , Massey Stephen C. 
Published: January 2005

AbstractThe fluorescent dye 4,6‐diamino‐2‐phenylindole (DAPI) has previously been used to label starburst amacrine cells selectively in the rabbit retina and AII amacrine cells in the cat retina. Using the rabbit retina, we show that intraocular injection of DAPI labels starburst amacrine cells as seen 1–2 days later. In contrast, after a brief in vitro incubation with DAPI, AII amacrine cells are selectively labeled. Amacrine cells were identified by intracellular staining with Lucifer Yellow. AII amacrine cells are arranged in a regular mosaic with a density of 2,800 cells/mm2 near the visual streak declining to about 500 cells/mm2 in the far periphery. The coverage of the lobular dendritic field in sublamina α is approximately 1.5 across the retina, but the coverage of the fine dendritic field in sublamina b increases from 3 centrally to 4 in the inferior periphery, and to above 8 in the superior periphery.
Distribution and developmental expression of the nerve terminal protein NT75 in the rat cerebellum
Authors: Wright David J. , Ritchie Teresa C. , Coulter Joe D. 
Published: January 2005

AbstractPrevious studies of the nerve terminal protein NT75 in the developing spinal cord have suggested an association between the appearance of NT75 immunoreactivity and the process of synaptogenesis. To examine the time course of NT75 expression further, the current study. Compared the localization of NT75 and the synaptic vesicle protein synaptophysin in the adult and developing rat cerebellum and in cerebellar tissue cultures. In the adult cerebellum, dense NT75 staining is confined to the molecular layer, where it is associated with parallel fiber endings of cerebellar granule cells. During development, NT75 immunoreactivity is first detectable in the cerebellar cortex as a dense band of staining in the deepest portion of the molecular layer at postnatal day 10. The stained zone expands to occupy a progressively greater portion of the molecular layer until about postnatal day 20. Synaptophysin staining occurs in granule cell processes earlier than NT75 and is found throughout the molecular layer by postnatal day 7. Quantitatively, rapid increases in both NT75 and synaptophysin occur in the first three postnatal weeks, with NT75 activity reaching levels exceeding the adult value by 50% over postnatal days 20 through 30, whereas synaptophysin plateaus at near adult levels by postnatal day 20. In cerebellar cultures, NT75 staining in neurites develops over several days, increasing coincidentally with development of synaptic contacts, whereas synaptophysin staining is already present in most neurites after only 1 day in vitro. The results indicate that NT75 expression in developing cerebellar granule cell nerve terminals is closely associated with the appearance of mature nerve terminals, suggesting that the protein may have a role in the formation/stabilization of the synaptic ending or in the mechanisms of synaptic transmission.
In situ hybridization analysis of the FMRFamide neuropeptide gene in Drosophila. II. Constancy in the cellular pattern of expression during metamorphosis
Authors: O'Brien Martha A. , Schneider Lynne E. , Taghert Paul H. 
Published: January 2005

AbstractWe have studied changes in the pattern of specific neuropeptide gene expression during the metamorphosis of the Drosophila nervous system. Prior to metamorphosis, the Drosophila FMRFamide gene is expressed exclusively within the central nervous system in a stereotyped pattern that comprises roughly 60 neurons (Schneider et al., '91). Using in situ hybridization, we found that the FMRFamide gene was continuously expressed throughout all stages examined: at each of 15 stages of adult development and through at least the first 10 days of adult life. There were no differences between the results observed with 2 exon‐specific hybridization probes, thus indicating little if any alternative splicing during postembryonic development. Despite many changes in the positions of individual hybridization signals due to the large‐scale reorganization of the nervous system, the continuous pattern of gene expression through adult development permitted many adult signals to be identified as larval signals. We concluded that the adult pattern of FMRFamide gene expression was largely derived from persistent larval neurons. Adult‐specific hybridization signals in the brain and ventral ganglion were also detected and these corresponded to many of the ∼ 40 adult‐specific FMRFamide‐immunoreactive neurons. One specific larval signal was lost during adult development and the intensities of other signals fluctuated in reproducible manners. These stereotyped differences in hybridization signal intensity resemble similar observations made in larval stages (Schneider et al., '91) and support the hypothesis that the steady‐state levels of FMRFamide transcripts are differentially regulated among the diverse neurons that express the gene.
Sexually dimorphic distribution of a galanin‐like peptide in the central nervous system of the teleost fish Poecilia latipinna
Authors: Cornbrooks Ellen B. , Parsons Rodney L. 
Published: January 2005

AbstractImmunohistochemical techniques were used to visualize areas of the brain and spinal cord containing a galaninlike peptide in the teleost fish, the sailfin molly. Galaninlike immunoreactivity (GAL‐LI) in both males and females was identified in neurons in the nucleus preopticus periventricularis, nucleus lateralis tuberis, and nucleus commissuralis. GAL‐LI fibers had a comparable distribution in the forebrain, preoptic, hypothalamic, and visceral sensory areas of both sexes. In striking contrast to these areas, the optic tectum, torus semicircular is, brainstem tegmentum, and spinal cord of the male contained much higher levels of GAL‐LI than the female. GAL‐LI in these dimorphic areas in the female was limited to single fiber bundles in the ventromedial tegmentum and in the trigeminal system. Additionally, a population of neurons in the preoptic nucleus was found to contain GAL‐LI in the male only.Sexual dimorphism was especially prominent in the spinal cord, where extensive GAL‐LI fibers were found in the male only. These fibers were oriented in the longitudinal plane and confined largely to the gray matter. Comparative studies were performed on the goldfish spinal cord, in which GAL‐LI was localized solely in the dorsal horn and exhibited no sexual dimorphism. Further, examination of spinal cord material from neonatal mollies revealed a lack of spinal GAL‐LI at this developmental stage. As the extent of GAL‐LI in the male molly spinal cord differs from both the goldfish and from that reported for the mammalian spinal cord, and a prominent sexual dimorphism in GAL‐LI extends from the diencephalon to the caudal spinal cord, it is suggested that a galaninlike peptide may play a unique, sex‐specific role in this species.