bluuebunny/crossref_metadata_2025_split huggingface dataset:
Olivary morphology and olivocerebellar topography in adult lurcher mutant mice
Authors: Heckroth John A. , Eisenman Leonard M. 
Published: January 2005

AbstractIn adult lurcher mice, in which virtually all cerebellar Purkinje cells have degenerated as a direct consequence of mutant gene action, the inferior olivary complex suffers a severe retrograde transneuronal atrophy. Our analysis indicates a 63% cell loss in the lurcher inferior olive, homogeneously distributed between the medial and dorsal accessory, and principal olivary subdivisions. Olivary neurons are reduced in cross‐sectional area by 30% in lurcher mice, compared to normal controls. All olivary subdivisions morphologically identifiable in normal mice are also found in the lurcher inferior olive. Analysis of olivocerebellar topography by retrograde transport of lectin‐conjugated horseradish peroxidase and fluorogold, in both single and double labeling paradigms, reveals no abnormalities in the general organization of this highly ordered projection. This stability may be based on the initial establishment of the topographic pattern in late embryogenesis or early postnatal periods, prior to the onset of lurcher Purkinje cell degeneration, or, alternatively, the lurcher gene may not alter critical afferent and target characteristics at stages when the topographic relationship is being established. Once established, the olivocerebellar projection is apparently not dependent on the Purkinje cell for long‐term maintenance of its general topographic organization.
Evidence for new growth and regeneration of cut axons in developmental plasticity of the rubrospinal tract in the north american opossum
Authors: Xu Xiao M. , Martin George F. 
Published: January 2005

AbstractWe have shown previously that rubral axons can grow around a lesion of their spinal pathway in the developing opossum and that a critical period exists for that plasticity (Martin and Xu, Dev Brain Res 39:303, 1988). Since most rubrospinal neurons degenerate after axotomy during the critical period, we have proposed that plasticity results primarily from growth of late arriving axons around the lesion rather than regeneration of cut axons (Xu and Martin, J Comp Neurol 279:368, 1989). In the present study, we used a double‐labeling paradigm to test that hypothesis.Four groups of pouch young opossums received bilateral or unilateral injections of Fast Blue (FB) into the caudal thoracic or rostral lumbar cord (T12–L2) at different ages in order to label rubrospinal neurons. Three or 4 days later, the rubrospinal tract was transected unilaterally, four to five segments rostral to the injection(s). If the injection was unilateral, the lesion was made ipsilateral to it. The animals were maintained for about 1 month before a second marker, Diamidino Yellow (DY), was injected, usually bilaterally, between the FB injection(s) and the lesion. The animals were maintained for about 5 days before sacrifice and sections through the red nucleus and spinal cord were examined with a fluorescence microscope.During the critical period for plasticity, only a few rubral neurons contralateral to the lesion were labeled by FB alone, supporting our previous contention that most axotomized neurons degenerate. In contrast, many neurons were labeled by DY alone, indicating that their axons were not present in the caudal cord at the time of the FB injection and that they grew around the lesion during the 1 month survival to incorporate DY. A few double‐labeled neurons were also found. One interpretation of such neurons is that they survived axotomy, as evidenced by the presence of FB, and supported axons which grew around the lesion to take up DY. Another interpretation is that they supported late growing axons which incorporated residual FB as well as DY. In order to choose between these alternatives, a similar double‐labeling paradigm was carried out, but with removal of FB at the time of the lesion. Since a few neurons were still double labeled, we conclude that regeneration of cut axons also contributed to rubrospinal plasticity.Our results support our previous suggestion that developmental plasticity of the rubrospinal tract results primarily from growth of late arriving axons around the lesion, but they also suggest that regeneration of cut axons occurs.
Calcitonin gene‐related peptide and corneal innervation: A developmental study in the rat
Authors: Jones Mark A. , Marfurt Carl F. 
Published: January 2005

AbstractThe development of calcitonin gene‐related peptide‐like immunoreactive (CGRP‐LI) nerves was studied in neonatal and adult rat corneas stained immunohistochemically according to an avidin biotin peroxidase procedure. At birth, rat corneas already contained dense plexuses of CGRP‐LI nerve fibers. Most of the nerves entered the cornea in 12–15 prominent stromal nerve bundles located at regular intervals around the circumference of the cornea. Fibers in these bundles entered the epithelium approximately midway between the limbus and the center of the cornea and supplied extensive central and pericentral areas of the tissue. In addition, smaller numbers of axons entered the cornea individually and in small fascicles located in between the larger bundles and supplied mainly peripheral territory. In the epithelium, the CGRP‐LI nerves formed a complex, highly anastomotic meshwork that ramified uniformly throughout central and peripheral areas of the tissue. Fibers in the plexus gave origin to numerous short, stout terminal axons that extended into the adjacent epithelium in all directions with no preferred orientation. During the first week of neonatal life, several changes in CGRP‐LI innervation occurred: (1) the innervation density of the central and pericentral cornea increased relative to the peripheral cornea; (2) intraepithelial axons became progressively longer, increased in branching complexity, and oriented preferentially towards the center of the cornea; and (3) a dense innervation of the corneoscleral limbus and, in particular, the branches of the marginal artery, developed. Midway through the second week of life, immature versions of Corneal epithelial “leashes,” the dominant feature of the adult corneal innervation, were first observed. Over the next 10 days, the leash formations in the central and pericentral cornea gradually became more complex and gave rise to greater numbers of terminal axons, compared to developing leashes in the peripheral cornea. The mature pattern of corneal CGRP‐LI innervation was reached on day 21 and remained constant (except for compensatory growth‐related elongation of axons) for at least the first 6 months of life. Transection of the ophthalmomaxillary nerve or neonatal administration of the sensory neurotoxin capsaicin resulted in the total loss of CGRP‐LI staining from the cornea. In contrast, removal of the superior cervical ganglion had no effect on corneal CGRP‐LI staining. The extraordinary density and complexity of the CGRP‐LI innervation of the rat cornea demonstrated at all stages of development in this study suggests that these nerves may play important roles in corneal sensory, reflex, and trophic functions.
Structure of the macroglia of the retina: Sharing and division of labour between astrocytes and Müller cells
Authors: Holländer Horstmar , Makarov Felix , Dreher Zofia , van Driel Diana , Chan‐Ling Tailoi , Stone Jonathan 
Published: January 2005

AbstractA detailed comparison is made between astrocytes and Müller cells of the cat's retina, with emphasis on their structural specialisations. Evidence is presented that astrocytes and Müller cells both contribute to the formation of the inner glia limitans of the retina, the glia limitans of vessels, and the glial sheaths of neurones. In particular, it was noted that both astrocytes and Müller cells wrap bundles of ganglion cells axons, that both contribute processes to the glial convergence on the initial segments and node‐like structures of axons, and that both wrap the somas of neurones in the ganglion cell layer. Further, it was noted that adherent junctions form between astrocytes, between Müller cells, and between astrocytes and Müller cells, but not between these cells and neurones, or among neurones. These similarities suggest that astrocytes and Müller cells function interchangeably in many respects, and we suggest that they be regarded as variants of macroglia.Quantitative differences between astrocytes and Müller cells were noted in their ensheathment of neurones. In particular, the glial sheaths around the somas of ganglion cells are formed predominantly by Müller cells, and the glial processes attached to node‐like specialisations of their axons are formed mainly by astrocytes. One qualitative difference was noted between the two cell classes. The gap junctions which form between astrocytes do not form between Müller cells or between cells of the two classes. From these differences, and previously established features of their shape, orientation, distribution and origin, a hypothesis is developed of the specialisation of macroglia represented by Müller cells.
Prenatal descent of rubrospinal fibers through the spinal cord of the rat
Authors: Lakke E. A. J. F. , Marani E. 
Published: January 2005

AbstractThis study is the first description of the descent of rubrospinal fibers through the spinal cord of the rat fetus. Either horseradish peroxidase or wheat germ agglutinin‐horseradish peroxidase conjugate was injected into the spinal cord, at different levels and at different gestational ages. At embryonic day 17 (E17) fibers from all subdivisions of the nucleus ruber (NR) started their descent towards the spinal cord. At E18 fibers from the ventrolateral NR reached the lower cervical spinal cord, and those from the caudal NR reached the lower thoracic spinal cord. At E19 fibers from the dorsomedial NR and from the parvicellular NR had just reached the cervical spinal cord, while fibers from the ventrolateral and caudal NR descended to lower thoracic levels. At E21 fibers from the dorsomedial NR reached the lower cervical spinal cord. Fibers from the ventrolateral and caudal NR completed their descent through the lumbosacral spinal cord during the first three postnatal days. During their descent the rubrospinal fibers were confined to the white matter of the spinal cord.The earliest descending fibers originated in the caudal NR. Fibers from the caudal part of each magnocellular subdivision of the NR descended before their rostral counterparts. Fibers from the dorsomedial NR only reached the cervical enlargement as the fibers from the ventrolateral NR descended through the cervical enlargement. The somatotopy of the adult rubrospinal projection reflects this sequence; the dorsomedial NR (dmNR) projects to the cervical spinal cord, and the ventrolateral NR (vlNR) projects to the lumbosacral spinal cord. In general, early descending fibers originated from neurons located caudally and ventrolaterally, while later descending fibers originated from neurons located progressively more rostrally and dorsomedially in the magnocellular NR.
Thalamic processing of vibrissal information in the rat. I. Afferent input to the medial ventral posterior and posterior nuclei
Authors: Chiaia Nicolas L. , Rhoades Robert W. , Bennett‐Clarke Carol A. , Fish Stephen E. , Killackey Herbert P. 
Published: January 2005

AbstractRetrograde tracing with true blue (TB) and diamidino yellow (DY) and anterograde tracing with either wheatgerm agglutinin–conjugated horseradish peroxidase (WGA‐HRP) or Phaseolus vulgaris leucoagglutinin (PHA‐L) were employed to investigate the projections from trigeminal nucleus principalis (PrV) and trigeminal subnucleus interpolaris (SpI) to their targets in the medial ventral posterior (VPM) and posterior (POm) nuclei of the thalamus. Many more cells in both PrV and SpI were labeled by tracer injections into VPM than into POm. Only a very small number of double‐labeled neurons were observed in either PrV or SpI. However, a significantly higher percentage of SpI cells projected to POm or to both POm and VPM than was the case for PrV. Anterograde tracing with WGA‐HRP showed that the projections from both PrV and SpI to VPM were much denser than those from the same nuclei to POm. Small injections of PHA‐L into either PrV or SpI produced a focus of fairly dense labeling in VPM and much more diffuse terminal labeling in POm. These anatomical data provide evidence for two separate trigeminothalamic pathways, one originating from PrV and the second originating from SpI. Both of these pathways converge and diverge at the thalamic level. That is, information from the PrV pathway and from the SpI pathway are both provided to VPM in a morphologically restricted fashion and to POm in a morphologically widespread fashion.
Serotoninergic innervation of the ferret cerebral cortex. II. Postnatal development
Authors: Voigt Thomas , de Lima Ana Dolabela 
Published: January 2005

AbstractWe have investigated the serotoninergic innervation of the ferret cortex from the day of birth to adulthood with immunohistochemical techniques. Due to the premature birth of ferrets, this period spans the entire generation of cells located within the upper cortical layers and their subsequent migration to their final positions. Already at birth, serotoninergic fibers innervate the developing cortex. This innervation is most dense within the marginal zone, the subplate region, and the lower portion of the cortical plate. As long as cell migration continues, serotoninergic fibers enter the expanding portions of the cortex. Only the region just below the marginal zone where newly arriving cells are added to the cortical plate is not innervated by the ingrowing fibers. When the bulk of cell migration ceases, during the third postnatal week, this gap disappears and the fibers gradually form a continuous innervation from the pia to the ventricle. As the cortex matures, the serotoninergic fibers become successively confined to the upper layers, to generate the adult pattern. In the adult ferret cortex, the highest innervation density is found within layers 1, 2, and 3, with a much sparser innervation within the lower layers (Voigt and de Lima, J. Comp. Neurol. 314:403–414, 1991). The dense innervation in the deep cortical layers is only transient, virtually disappearing toward adulthood. These results suggest that serotoninergic axons innervate cortical layers as soon as newly arriving cells reach their final positions within the cortex. This early innervation lends support to the idea that serotonin may play a role during development of the cerebral cortex.
The distribution of neurotransmitters and neurotransmitter‐related enzymes in the dorsomedial telencephalon of the pigeon (Columba livia)
Authors: Krebs John R. , Erichsen Jonathan T. , Bingman Verner P. 
Published: January 2005

AbstractImmunoreactivity to four neurotransmitters/transmitter‐related enzymes was found in the dorsomedial telencephalon (hippocampal region) of the pigeon. Putative afferent fibers containing choline acetyltransferase‐like, serotonin‐like, and tyrosine hydroxylase‐like immunoreactivity were seen in a fiber tract passing through the septo‐hippocampal junction and along the medial wall of the hippocampal region. The most intensive labeling of neuropil and terminals of all four substances was found in the dorsomedial area of the hippocampal region. Glutamic acid decarboxylase‐like immunoreactivity was seen in sparsely scattered cells throughout the region. These results are discussed in relation to hypotheses about the boundaries and subdivisions of the hippocampal region of the pigeon.
Thalamic projections to the lateral suprasylvian visual area in cats with neonatal or adult visual cortex damage
Authors: Kalil Ronald E. , Tong Lillian , Spear Peter D. 
Published: January 2005

AbstractPrevious transneuronal anterograde tracing studies have shown that the retino‐thalamic pathway to the posteromedial lateral suprasylvian (PMLS) visual area of cortex is heavier than normal in adult cats that received neonatal damage to visual cortical areas 17, 18, and 19. In contrast, the strength of this projection does not appear to differ from that in normal animals in cats that experienced visual cortex damage as adults. In the present study, we used retrograde tracing methods to identify the thalamic cells that project to the PMLS cortex in adult cats that had received a lesion of visual cortex during infancy or adulthood. In five kittens, a unilateral visual cortex lesion was made on the day of birth, and horseradish peroxidase (HRP) was injected into the PMLS cortex of both hemispheres when the animals were 10.5 to 13 months old. For comparison, HRP was injected bilaterally into the PMLS cortex of three cats 6.5 to 13.5 months after they received a similar unilateral visual cortex lesion as adults. In cats with a neonatal lesion, retrograde labeling was found in the large neurons that survive in the otherwise degenerated layers A and A1 of the lateral geniculate nucleus (LGN) ipsilateral to the lesion. Retrograde labeling of A‐layer neurons was not seen in the undamaged hemisphere of these animals or in either hemisphere of animals that had received a lesion as adults. As in normal adult cats, retrograde labeling also was present in the C layers of the LGN, the medial interlaminar nucleus, the posterior nucleus of Rioch, the lateral posterior nucleus, and the pulvinar nucleus ipsilateral to a neonatal or adult lesion. Quantitative estimates indicate that the number of labeled cells is much larger than normal in the C layers of the LGN ipsilateral to a neonatal visual cortex lesion. Thus the results indicate that the heavier than normal projection from the thalamus to PMLS cortex that exists in adult cats after neonatal visual cortex damage arises, at least in part, from surviving LGN neurons in the A and C layers of the LGN. Although several thalamic nuclei, as well as the C layers of the LGN, continue to project to PMLS cortex after an adult visual cortex lesion, these projections appear not to be affected significantly by the lesion.
An immunocytochemical analysis of the lateral geniculate complex in the pigeon (Columba livia)
Authors: Güntürkün Onur , Karten Harvey J. 
Published: January 2005

AbstractThe lateral geniculate complex (GL) of pigeons was investigated with respect to its immunohistochemical characteristics, retinal afferents, and the putative transmitters/modulators of its neurons. The distributions of serotonin‐, choline acetyltransferase‐, glutamic acid decarboxylase‐, tyrosine hydroxylase‐, neuropeptide Y‐ (NPY), substance P‐ (SP), neurotensin‐ (NT), cholecystokinin‐ (CCK), and leucine‐enkephalin‐ (L‐ENK) like immunoreactive perikarya and fibers were mapped. Retinal projections were studied following injections of Rhodamine‐B‐isothiocyanate into the vitreous. Transmitter‐specific projections onto the visual Wulst and the optic tectum were studied by simultaneous double‐labelling of retrograde tracer molecules and immunocytochemical labelling.The GL can be divided into three major subdivisions, the n. geniculatus lateralis, pars dorsalis (GLd; previously designated as the n. opticus principalis thalami, OPT), the n. marginalis tractus optici (nMOT), and the n. geniculatus lateralis, pars ventralis (GLv). All three subdivisions are retinorecipient. The GLd can be further subdivided into at least five components differing in their immunohistochemical characteristics: n. lateralis anterior (LA); n. dorsolateralis anterior thalami, pars lateralis (DLL), n. dorsolateralis anterior thalami, pars magnocellularis (DLAmc); n. lateralis dorsalis nuclei optici principalis thalami (LdOPT); and n. suprarotundus (SpRt). The LdOPT consists of an area of dense CCK‐like and NT‐like terminals of probable retinal origin. Three subnuclei (DLL, DLAmc, SpRt) were shown to project to the visual Wulst. Cholinergic and cholecystokinergic relay neurons participated in this projection.The nMOT occupies a position between the GLd and GLv and encircles the rostral pole of n. rotundus and the LA. It is characterized mainly by medium sized NPY‐like perikarya which were shown to project onto the ipsilateral optic tectum. Bands of NPY‐like fibers in the tectal layers 2, 4, and 7 could at least in part be due to this projection of the nMOT. Most of the antisera used revealed transmitter/modulator‐specific fiber systems in the GLv which often showed a layer‐specific distribution. Perikaryal labelling was only obtained with glutamic acid decarboxylase.On the basis of its chemoarchitectonics, topography, and connectional pattern, the GLd complex of pigeons is most directly equivalent to the mammalian GLd. However, although the different subdivisions of the avian GLd may represent functionally different channels within the thalamofugal pathway similar to the lamina‐specific differentiation within the mammalian geniculostriate projection, direct comparison of subnuclei of birds and mammals is not justified at this time. The nMOT appears similar to the intergeniculate leaflet (IGL) and the avian GLv clearly corresponds in many features to the mammalian GLv.
Light and electron microscope study of GABA‐immunoreactive neurones in Lamina III of rat spinal cord
Authors: Powell James J. , Todd Andrew J. 
Published: January 2005

AbstractIn order to determine whether different morphological types of neurone in lamina III of rat spinal dorsal horn contain different neurotransmitters, a combined Golgi and immunocytochemical study was performed. Semithin sections through the cell bodies of 52 Golgi‐impregnated neurones in this lamina were tested with antisera to GABA and glycine. Thirty of these cells were immunoreactive with anti‐GABA antiserum and 25 of these also showed glycine‐like immunoreactivity. These cells had dendrites which were oriented along the rostrocaudal axis and occupied lamina III, with some extension into lamina IV and the ventral half of lamina II. Although some of the nonimmunoreactive cells had similar morphology, many of them had dendrites which passed in a dorsal and/or ventral direction and crossed laminar boundaries. Three of the neurones which were immunoreactive with both antisera were examined with the electron microscope. These cells received a variety of synapses including some from axons which resembled low threshold myelinated mechanoreceptive primary afferents.These results indicate that there is a relationship between morphology and function for neurones in lamina III. It is suggested that the inhibitory neurones which contain both GABA and glycine selectively regulate the transmission of information from low threshold mechanoreceptive primary afferents to other dorsal horn neurones.