bluuebunny/crossref_metadata_2025_split huggingface dataset:
Position of axons in the cat's optic tract in relation to their retinal origin and chiasmatic pathway
Authors: Reese B. E. , Guillery R. W. , Marzi C. A. , Tassinari G. 
Published: January 2005

AbstractThe positions of the crossed and uncrossed optic axons of distinct diameter classes has been examined in the optic tract of the adult cat. In addition, the retinal origin of axons occupying different positions within the tract has been studied. Since the position of a fibre within the optic tract reflects its time of arrival during development, we have used axonal position as an indicator of age and have related this to the chiasmatic pathway choice of the axons.Cats were either monocularly enucleated, to reveal the position and diameter of surviving crossed and uncrossed optic axons in semithin and thin sections, or implants of horseradish peroxidase (HRP) were placed so as to retrogradely label the ganglion cells giving rise to axons within the deep (early arriving), or superficial (later arriving) parts of the tract selectively. This was accomplished by either (1) surgically implanting HRP into the superficial portion of the optic tract, via a transbuccal approach, or (2) making such a transbuccal transection of the superficial fibres, followed by intracerebral injections of HRP to retrogradely label the surviving, deeper, optic axons from their target nuclei.The deep parts of the optic tract contain fine and medium, crossed and uncrossed axons arising from mainly medium sized cells in the contralateral nasal and the ipsilateral temporal retina; there is a clear line of decussation. In contrast, the superficial parts of the tract contain mainly fine diameter axons arising from small cells in the whole contralateral retina, and a small proportion of large diameter axons arising from large, alpha cells in the whole contralateral retina and in the ipsilateral temporal retina.The likelihood that axons from the temporal retina will project contralaterally therefore increases as development proceeds, since these axons are found in the superficial parts of the tract only. This suggests that a time‐dependent signal that weakens with age is responsible for directing early arriving optic axons from the temporal retina to take an exclusively uncrossed course.
Enkephalin immunoreactivity and messenger RNA in a discrete projection from the nucleus of the solitary tract to the nucleus ambiguus in the rat
Authors: Cunningham E. T. , Simmons D. M. , Swanson L. W. , Sawchenko P. E. 
Published: January 2005

AbstractPrevious work described in the rat a circumscribed, partly somatostatinergic, interneuronal projection from the esophageal afferent part of the nucleus of the solitary tract (NTSc) to esophageal motor neurons in the compact formation of the nucleus ambiguus(NAcf; Cunningham and Sawchenko, J Neurosci 9:1668, 1989). In the present study, axonal transport, immunohistochemical and in situ hybridization histochemical techniques were used to determine whether enkephalin (ENK), a peptide known to be expressed in a number of somatostatin‐containing medullary cell groups, is also expressed in the projection from the NTSc to the NAcf. The results may be summarized as follows; 1) cells immunoreactive (IR) for prepro‐enkephalin (ppENK)‐derived peptides were found in the NTSc in colchicine‐pretreated animals; in untreated animals, a dense ENK‐IR terminal field was observed in the NAcf; sections stained with antisera against dynorphin‐related peptides showed sparse staining in both regions; 2) signal indicating the presence of ppENK messenger RNA (mRNA) was found over the NTSc, including over a majority of cells identified using a retrograde tracing technique as projecting to the region of the NAcf; the signal for ppENK mRNA signal was greater than that for prepro‐somatostatin (ppSS) in the NTSc; 3) a combined anterograde tracing‐immunohistochemical technique demonstrated a strong correspondence between the distribution of inputs from the NTS to the NAcf, and the distribution of endogenous ENK‐IR varicosities; in addition, leucine (L)‐ENK‐IR was found in an appreciable number of varicosities in the NAcf that had been anterogradely labeled from the NTSc; 4) unilateral electrolytic lesions of the rostromedial NTS, which included the central subnucleus, virtually eliminated ENK‐IR in the ipsilateral NAcf, while staining on the contralateral side was unaffected. Taken together, these studies provide evidence that ppENK‐ and ppSS‐derived peptides are expressed in the pathway from the NTSc to the NAcf, a pathway thought to play a role in the reflex control of esophageal peristalsis.
Formation of ganglia in the gut of the chick embryo
Authors: Epstein Miles L. , Poulsen Kristian T. , Thiboldeaux Robert 
Published: January 2005

AbstractWe have examined the formation of myenteric ganglia in the developing avian enteric nervous system. The monoclonal antibody HNK‐1 was used to identify neural‐crest‐derived cells in whole mounts of fore‐ and midgut of chick embryos. We find that the crest‐derived cells extend processes to their neighbors and form a complex network in the wall of the gut. Formation of this network is an unusual behavior of crest‐derived cells and suggests the gut microenvironment is critical to this behavior. This cellular network disappears after ablation of the vagal neural crest, indicating the HNK‐1‐stained cellular network arises from crest‐derived cells. The network is found in the gut wall before the vagal nerve fibers are present. This network is first found in the primordium of the proventriculus, distal to the evagination of the lung buds, and progresses just proximal to the yolk stalk at embryonic day (E)3.5 and almost to the ileocecal junction at E5.5. The number of cells and the complexity of the network decrease in a rostral‐caudal direction down the length of the gut at these stages. The leading edge of the network consists of cells serially arranged in longitudinally running strands. The organization of the network changes with increasing embryonic age; we have focused on network changes in the proventriculus. In the primordium of the proventriculus at E3.5, the network consists of a cluster of one or two adjacent crest‐derived cells, which extend processes to a number of neighboring crest‐derived cells. At E5.5 large increases in the number of cells per cluster and in the length of cellular connectives between clusters are apparent. At E6.5 a crude meshwork of clusters is seen. At E10.5 the arrangement of cell clusters resembles the pattern of ganglia found in the adult myenteric plexus. This network may provide the environmental cues for the differentiation of enteric neurons and a framework for the pattern of ganglia found in the adult enteric nervous system.
Dopamine‐immunoreactive neurones in the central nervous system of the pond snail Lymnaea stagnalis
Authors: Elekes K. , Kemenes G. , Hiripi L. , Geffard M. , Benjamin P. R. 
Published: January 2005

AbstractThe distribution of dopamine and dopamine‐immunoreactive neurones was studied in the central nervous system of the snail Lymnaea stagnalis. The results from immunocytochemical labelling were compared with those from the application of the glyoxylic acid fluorescence method and 6‐hydroxydopamine‐induced pigment labelling. Comparisons were also made between the number of dopamine immunoreactive neurones and the dopamine content of the ganglia, measured by high‐performance liquid chromatography.Dopamine immunocytochemistry proved to be superior to the other two histochemical techniques in terms of specificity and sensitivity. The 6‐hydroxydopamine‐induced pigment labelling failed to prove a useful tool for the in vivo identification of all dopamine‐containing neurones. The distribution and number of dopamine‐immunoreactive neurones and levels of biochemically measured dopamine in specific ganglia showed a close correspondence. By using the results of the dopamine immunocytochemistry and glyoxylic acid technique, a detailed map of dopamine‐containing neurones was constructed. Dopamine‐containing inter‐ and intra‐ganglionic axon tracts were also demonstrated. The mapping of dopamine‐containing neurones will facilitate further neurophysiological analysis of dopaminergic neural mechanisms in Lymnaea.
Trigeminal projections to the nucleus submedius of the thalamus in the rat
Authors: Yoshida Atsushi , Dostrovsky Jonathan O. , Sessle Barry J. , Chiang Chen Yu 
Published: January 2005

AbstractMethods involving the anterograde and retrograde transport of wheat‐germ agglutinin conjugated horseradish peroxidase and the retrograde transport of Fluoro‐Gold were used in rats to examine the distribution within the spinal trigeminal nucleus of trigeminal neurons projecting to the nucleus submedius (Sm) of the thalamus, as well as the distribution of axon terminals within the Sm. Following injections into the trigeminal nucleus, axon terminals were seen in the dorsal part of the anterior Sm; the terminals occurred bilaterally but had an obvious contralateral dominance. To help determine the precise location of the Sm‐petal neurons, the border between trigeminal subnuclei interpolaris and caudalis was examined by the use of immunohistochemical procedures for calcitonin gene‐related peptide (CGRP). The Sm‐petal neurons that were labeled retrogradely occurred only at the caudal interpolaris and rostral caudalis levels; the number of labeled neurons on the contralateral side was approximately six times that on the ipsilateral side. Most of these neurons were located in the ventral part of the caudal interpolaris and rostral caudalis and spinal trigeminal tract; in caudalis, the neurons were almost exclusively localized to its superficial layers. There were approximately three times more labeled neurons in interpolaris than in caudalis. In the experiments combined with immunohistochemistry for CGRP, many neurons (34%) were seen in proximity to CGRP‐like immunopositive fibers. These results suggest that the Sm of the rat receives its orofacial afferent inputs from brainstem neurons that are localized to the caudal interpolaris and rostral caudalis. In view of previous studies that have implicated these three structures in somatosensory function, and in particular nociception, our data point to a role for this direct projection from interpolaris and caudalis to Sm in the central processing of pain.
Intracerebral grafting of cultured autologous skin fibroblasts into the rat striatum: An assessment of graft size and ultrastructure
Authors: Kawaja Michael D. , Fagan Anne M. , Firestein Bonnie L. , Gage Fred H. 
Published: January 2005

AbstractTo identify a suitable donor cell population for gene therapy applications to the central nervous system, primary fibroblasts isolated from skin biopsies and maintained in culture are employed as autologous cells for intracerebral grafting within the adult rat striatum. Results from the present investigation reveal that cultured primary skin fibroblasts cease to proliferate once they reach confluence; these cells are thus contact inhibited in vitro. Following implantation within the striatum, the volume of the primary fibroblast grafts, stained immunohistochemically for fibronectin, does not differ significantly at 3 and 8 weeks. The graft size is dependent on the density of the cell suspension, but not dependent on either the number of passages the cells are taken through in culture prior to grafting or on the postoperative survival period. Ultrastructural evidence reveals that at 8 weeks the grafts are composed primarily of collagen and fibroblasts with rough endoplasmic reticulum and vesicles. Reactive astrocytic processes and phagocytic cells are also present in the grafts, The grafts are extensively vascularized with capillaries composed of nonfenestrated endothelium; intercellular junctions are evident at sites of apposition between endothelial cells. It is concluded that primary skin fibroblasts are able to survive for at least 8 weeks following intracerebral implantation and continue to synthesize collagen and fibronectin in vivo. Also, the grafts maintain a constant volume between 3 and 8 weeks, thereby indicating that primary skin fibroblasts do not produce tumors. Finally, dynamic host‐to‐graft interactions‐including phagocytic migration, astrocytic hypertrophy and infiltration within the grafts, and angiogene‐sis‐are features that constitute the structural integration of primary skin fibroblasts grafted within the adult rat central nervous system.
Localization of serotonin, tyrosine hydroxylase, and leu‐enkephalin immunoreactive cells in the brainstem of the horn shark, Heterodontus francisci
Authors: Stuesse Sherry L. , Cruce William L. R. , Northcutt R. Glenn 
Published: January 2005

AbstractIn previous studies on reptiles and elasmobranchs, we determined that some reticular groups are either absent or may be displaced compared to their locations in mammals. For example, nucleus raphe dorsalis, the largest serotoninergic cell group in mammals, is not present in rays, skates, or guitarfish. In the present study, we chose heterodontid sharks, a sister group to these batoids, for an out‐group comparison of this and other characters. We identified cells in the brainstem of Heterodontus francisci by use of antibodies against tyrosine hydroxylase, serotonin, or leu‐enkephalin and compared the distribution of these nuclei to descriptions in mammals and other elasmobranchs. The majority of tyrosine hydroxylase‐positive cells were found in the midbrain tegmentum (A8–A10) and the hypothalamus. In addition, putative A1, A2, A5, A7 (noradrenergic) groups were found in the metencephalon and myelencephalon. Serotonin‐positive cells were found in raphe nuclei and scattered lateral to the raphe. We identified probable homologues to raphe pallidus, raphe obscurus, raphe magnus, and raphe centralis superior (B8) cell groups, which have been described in mammals. A cluster of cells dorsomedial to the medial longitudinal fasciculus was identified as raphe dorsalis. The distributions of leu‐enkephalin and serotonin immunoreactive cells were similar to each other, but the tyrosine‐hydroxylase immunoreactive cells rarely intermingle with the former two immunoreactive cell types. Other reticular groups that contained both serotonin‐and leu‐enkephalin‐positive cells included reticularis (r.) ventralis, r. magnocellularis, r. paragigantocellularis lateralis, r. pontis caudalis, and r. pontis oralis medialis and lateralis. Thus, this shark contains many of the major brainstem raphe and catecholaminergic cell groups described for rats, but the relative distribution of the immunopositive cell groups differs in mammals and cartilaginous fish.
Mapping of glial fibrillary acidic protein‐immunoreactivity in the rat forebrain and mesencephalon by computerized image analysis
Authors: Zilles Karl , Hajós Ferenc , Kálmán Mihály , Schleicher Axel 
Published: January 2005

AbstractComputer‐assisted image analysis was used to map the regional distribution of glial fibrillary acidic protein‐immunoreactive (GFAP‐IR) astrocytes in the rat forebrain, and mesencephalon. A complete survey of packing densities of GFAP‐IR structures was performed. Computer maps revealed high values in the outer and inner layers of the cortex, some hippocampal and olfactory bulb layers, prepiriform cortex, dorsal part of the caudate‐putamen, globus pallidus, lateral septum, reticular thalamic nucleus, lateral habenular nucleus, circumventricular organs, nuclei of the medial hypothalamus, substantia nigra, interpeduncular nucleus, and mamillary body. These correspond to regions of the embryonic pial and ventricular brain surfaces, which undergo developmental alterations including growth and various forms of internalization. From this we conclude that in the adult brain, astrocytes of high GFAP‐IR are derivatives of surface‐contact glia, whereas those located in areas having developed by the local thickening of the neural tube wall show reduced or no GFAP‐IR.
Calcium‐binding protein (calbindin‐D28K) and parvalbumin immunocytochemistry in the normal and epileptic human hippocampus
Authors: Sloviter Robert S. , Sollas Anne L. , Barbaro Nicholas M. , Laxer Kenneth D. 
Published: January 2005

AbstractThe calcium‐binding proteins calbindin‐D28K (CaBP) and parvalbumin (PV) were localized in the “normal” and “epileptic” human hippocampus to address the possible relationship between the expression of these constitutive cytosolic calcium‐binding proteins and the resistance or selective vulnerability of different hippocampal neuron populations in temporal lobe epilepsy. Compared to rodents and a baboon (Papio papio), the pattern of CaBP‐like immunoreactivity (LI) in the “normal” human hippocampus is unique. CaBP‐LI is present in the dentate granule cells, neurons of the “resistant zone” (area CA2), and presumed interneurons of all regions. Unlike rodent and baboon CA1 pyramidal cells, human CA1 pyramidal cells appear to be devoid of CaBP‐LI. Thus, the relatively resistant dentate granule cells and CA2 pyramidal cells are the only human hippocampal principal cells that contain CaBP‐LI normally. As in lower mammals, PV‐LI is present exclusively in interneurons of all human hippocampal subregions.CaBP‐ and PV‐LI were localized in hippocampi surgically removed in the treatment of intractable temporal lobe epilepsy to determine whether surviving hippocampal cells were those that express these calcium‐binding proteins. Hippocampi removed from patients with tumors or arteriovenous malformations that were associated with complex partial seizures arising from this region appeared relatively normal histologically. CaBP‐ and PV‐LI in this patient group appeared similar to that seen in autopsy controls. Conversely, “cryptogenic” epileptics, who exhibit hippocampal sclerosis as the only lesion associated with the epilepsy, exhibited a preferential survival of hippocampal cells that were CaBP‐ or PV‐immunoreactive. In the dentate hilus, which normally contains few CaBP‐LI neurons, most of the few surviving hilar neurons were CaBP‐immunoreactive. Their number and darkness of staining suggests that CaBP synthesis may be increased in cells that survive. Despite an obvious decrease of PV‐LI specifically in the damaged parts of the sclerotic hippocampi, PV‐immunoreactive interneurons were often among the few surviving cells. Nevertheless, large expanses of the surviving granule cell layer appeared to have lost the PV‐immunoreactive axosomatic fiber plexus.These results reveal a unique and striking correlation between the human hippocampal cells that normally express these calcium‐binding proteins and those that survive in the sclerotic epileptic hippocampus.
Use of a digital brain atlas to compare the distribution of NGF‐ and bFGF‐protected cholinergic neurons
Authors: Schwaber James S. , Due Bryan E. , Rogers Wade T. , Junard Emmanuel O. , Sharma Anita , Hefti Franz 
Published: January 2005

AbstractThe effectiveness of basic fibroblast growth factor and nerve growth factor in preventing the lesion‐induced disappearance of septal cholinergic neurons was compared by using a computerized data‐acquisition system and a digital brain atlas that yielded quantitative and distributional information. Adult rats were given unilateral partial transections of the fimbria and then received daily intraventricular injection of one of the growth factors for 15 days. Given the high degree of co‐localization of nerve growth factor receptors with choline acetyltransferase in these areas, cholinergic neurons were identified by nerve growth factor receptor immunoreactivity. Their locations were plotted in the context of a three‐dimensional brain atlas permitting the analysis of relative distributions of cholinergic neurons in control brains and those of animals treated with each growth factor. The cholinergic cell disappearance induced by the partial fimbrial transection was restricted to the medial septal nucleus and the vertical limb of the diagonal band of Broca. Within the affected areas cholinergic cell disappearance increased gradually in severity from anterior to posterior levels of the septal nucleus. Both growth factors prevented the disappearance of cholinergic cell bodies in medial septal nucleus and vertical limb of the diagonal band. In lesioned control animals the unilateral cell disappearance amounted to 53.5% of the number of cholinergic neurons of the unlesioned side. Nerve growth factor and basic fibroblast growth factor reduced this disappearance to 13% and 28%, respectively. The distribution of cholinergic cells was the same in animals treated with each growth factor, suggesting that the two growth factors protect the same population of cholinergic neurons.
The regeneration of electroreceptors in kryptopterus
Authors: Bever Michele Miller , Borgens Richard B. 
Published: January 2005

AbstractThe regeneration of ampullary electroreceptors was studied in the living catfish, Kryptopterus, by differential interference contrast optics. Electroreceptors in this transparent catfish are found, among other places, along the proximal portion of each anal fin ray, while the distal portion does not contain electroreceptors. Upon interruption of the sensory innervation, the electroreceptors disappear but regenerate when the skin is reinnervated. In this study, we tested the role of the skin and nerve in receptor regeneration with the following two experiments. First, a plug of fin containing electroreceptors was removed to determine whether electroreceptors could form in regenerated skin after the complete removal of all of the receptors within an interradial zone of the anal fin. Second, a portion of anal fin that contained electroreceptors was excised and a graft of electro receptor‐free (EF) fin was sutured in its place to determine whether epidermis that does not normally contain these receptors can be induced to form them. These grafts were compared to control grafts taken from proximal electroreceptor‐containing (EC) fin. By 2 weeks following surgery, receptors were found in regenerated fin tissue and within the EC grafts. Electroreceptors also formed within most of the EF grafts. As electroreceptor regeneration does not require the presence of degenerated organs, and as electroreceptors can form in fin that normally does hot contain receptors, we suggest that the formation of electroreceptors does not require old target sites and that epidermal cells can be induced to form receptors upon contact by regenerating axons. We discuss as well the factors that influence the pattern of receptor reappearance.