bluuebunny/crossref_metadata_2025_split huggingface dataset:
Avenues for entry of peripherally administered protein to the central nervous system in mouse, rat, and squirrel monkey
Authors: Balin Brian J. , Broadwell Richard D. , Salcman Michael , El‐Kalliny Magdy 
Published: January 2005

AbstractPathways traversed by peripherally administered protein tracers for entry to the mammalian brain were investigated by light and electron microscopy. Native horseradish peroxidase (HRP) and wheat germ agglutinin (WGA) conjugated to peroxidase were administered intranasally, intravenously, or intraventricularly to mice; native HRP was delivered intranasally or intravenously to rats and squirrel monkeys. Unlike WGA‐HRP, native HRP administered intranasally passed freely through intercellular junctions of the olfactory epithelia to reach the olfactory bulbs of the CNS extracelluarly within 45–90 minutes in all species. The olfactory epithelium labeled with intravenously delivered HRP, which readily escaped vasculature supplying this epithelium. Blood‐borne peroxidase also exited fenestrated vessels of the dura mater and circumventricular organs. This HRP in the mouse, but not in the other species, passed from the dura mater through patent intercellular junctions within the arachnoid mater; in time, peroxidase reaction product in the mouse brain was associated with the pial surface, the Virchow‐Robin spaces of vessels penetrating the pial surface, perivascular clefts, and with phagocytic pericytes located on the abluminal surface of superficial and deep cerebral microvasculature. Blood‐borne HRP was endocytosed avidly at the luminal face of the cerebral endothelium in all species. WGA‐HRP and native HRP delivered intraventricularly to the mouse were not endocytosed appreciably at the abluminal surface of the endothelium; hence, the endocytosis of protein and internalization of cell surface membrane within the cerebral endothelium are vectorial. The low to non‐existent endocytic activity and internalization of membrane from the abluminal endothelial surface suggests that vesicular transport through the cerebral endothelium from blood to brain and from brain to blood does not occur. The extracellular pathways through which probe molecules enter the mammalian brain offer potential routes of passage for blood‐borne and airborne toxic, carcinogenic, infectious, and neurotoxic agents and addictive drugs, and for the delivery of chemotherapeutic agents to combat CNS infections and deficiency states. Methodological considerations are discussed for the interpretation of data derived from application of peroxidase to study the blood brain barrier.
Connections of the parahippocampal cortex in the cat. IV. Subcortical efferents
Authors: Witter Menno P. , Groenewegen Henk J. 
Published: January 2005

AbstractThe present report deals with the projections from the entorhinal and perirhinal cortices to subcortical forebrain structures and the brainstem in the cat. By using anterograde and retrograde tracing techniques, it could be demonstrated that the entire mediolateral extent of the parahippocampal cortex issues prominent projections to the dorsal and ventral striatum, the amygdala, and the claustrum. In addition, the entorhinal cortex sends projections to the septum and the diagonal band of Broca. Only the perirhinal cortex gives rise to a weak projection to the dorsolateral periaquaductal gray and the ventral pontine region. The major proportion of the subcortical projections originates in the perirhinal cortex and the lateral entorhinal cortex, whereas the medial entorhinal cortex has a much sparser output and sends no fibers to the amygdala. The subcortical projections from both the entorhinal cortex and the perirhinal cortex arise mostly from their deep layers. It was further found that these projections are topographically organized along the mediolateral axis of the parahippocampal cortex. This mediolateral axis is related to a ventrolateral to dorsomedial axis in the septum, a mediolateral axis in the amygdala and the ventral striatum, and a ventrodorsal coordinate in the dorsal striatum and the claustrum.A further topography was observed in the projections from the perirhinal cortex to the lateral amygdaloid nucleus. A rostrocaudal axis in the perirhinal cortex corresponds to a mediolateral axis in the lateral amygdaloid nucleus. The present observations are compared with data concerning the connectivity of the parahippocampal cortex with the hippocampal formation and other cortical structures. It is suggested that the parahippocampal cortex in the cat may be conceptualized as an interface between the hippocampal formation and several subcortical structures in the realm of the limbic and motor systems.
Frequency representation in auditory cortex of the common marmoset (Callithrix jacchus jacchus)
Authors: Aitkin Lindsay M. , Merzenich Michael M. , Irvine Dexter R. F. , Clarey Janine C. , Nelson John E. 
Published: January 2005

AbstractThe location and characteristics of the primary auditory cortex of the common marmoset, Callithrix jacchus jacchus, were determined in five anesthetized male adult animals by mapping the responses of cortical units and unit clusters to pure tone stimuli presented to the contralateral ear. The primary auditory cortex lies largely ventral to the lateral sulcus, the only major fissure on the lateral cortex of this smooth‐brained primate, but in some animals it may extend significantly down the ventral bank of this sulcus. Responses are distributed such that low best frequencies are found rostroventrally whereas high best frequencies occur caudally. The disposition of frequency‐band contours is fan‐shaped, with contours separating low‐frequency octaves nearly parallel to the lateral sulcus and high‐frequency (>8 kHz) contours perpendicular to that sulcus. Best frequencies range from 0.6 to 30 kHz across the primary field, but there is a disproportionate representation of the three octaves between 2 and 16 kHz. The most sensitive thresholds (as low as −2 dB SPL) are found between 7 and 9 kHz. The primary auditory cortex is similar in cytoarchitecture to that reported for the cat, showing a blurring of lamination in the middle layers (II–IV) and a preponderance of small cells in these merged layers, giving a highly granular appearance. The accessiblity of the cochlear representation on the gyral surface makes the marmoset an attractive animal for studies of primate auditory cortex.
Intracephalic transplants of freeze‐Stored rat hippocampal tissue
Authors: Sørensen Torben , Jensen Steen , Møller Anders , Zimmer Jens 
Published: January 2005

AbstractThe survival and cellular and connective organization of intracephalic transplants of developing, freeze‐stored rat hippocampal tissue were examined. Blocks of tissue containing the hippocampus and fascia dentata were obtained from late embryonic (E16‐‐E22) and early postnatal rats (P0‐‐P4) and immersed in a tissue culture medium with 10% of the cryoprotective agent DMSO, frozen at a cooling rate of approximately 1°C/minute, and stored for 1‐‐226 days in liquid nitrogen. After quick thawing and washing out of the DMSO the tissue blocks were transplanted to the brain of adult rats. From 2 weeks to 3 months later the recipient brains were processed histologically. The cellular and connective organization of the transplants and their interaction with the host brains were analyzed after thionin cell staining, Timm's staining for hippocampal and dentate afferents, immunohistochemical staining for enkephalin‐, CCK‐, and somatostatin‐reactive neurons and afferents, AChE staining for cholinergic afferents, and silver stains for fiber architectonics and tracing of connections by anterograde axonal degeneration.Freeze‐storage narrowed the range of donor ages with good transplant survival. The best surviving hippocampal and dentate transplants thus came from 17‐‐21‐day‐old embryos. There was no correlation between the length of storage and survival. Structurally the transplants of stored tissue were more frequently fragmented than the transplants of fresh tissue when located outside the brain parenchyma in the brain ventricles. This was in accordance with the results of a previous study of grafts of freeze‐stored and fresh hippocampal tissue placed in the anterior eye chamber. Despite the decrease in survival and the tendency for fragmentation many well‐structured and organotypically organized hippocampal and dentate transplants were recovered corresponding to the donor ages E19‐‐E21. In addition to the main cell types (granule cells and pyramidal cells) the freeze‐stored transplants also contained peptidergic nerve cells reacting for CCK, somatostatin, and enkephalin. The organization of the intrinsic nerve connections and the exchange of connections with the host brain were similar for transplants of stored and fresh tissue. Besides the consistent innervation of the hippocampal and dentate transplants by host cholinergic afferents monitored by AChE staining, several appropriately located dentate transplants thus sent mossy fibers to the host CA3. Others received host perforant path projection. A CA3‐associated transplant projection to the denervated perforant path zones in the host fascia dentata was also observed.From this and the previous study of intraocular grafting of freeze‐stored immature brain tissue we conclude that cryopreservation is a feasible method that increases both the practical and the experimental potentials of transplantation of CNS tissue.
Adrenaline‐synthesizing neurons in the medulla of the cat
Authors: Ruggiero David A. , Gatti Philip J. , Gillis Richard A. , Norman Wesley P. , Anwar Muhammad , Reis Donald J. 
Published: January 2005

AbstractIn this study, the distribution of neruons containing the adrenaline‐synthesizing enzyme phenylethanolamine‐N‐methyltransferase (PNMT) was mapped in the medulla of the cat. Data from recent studies in the rat suggest that the anatomical structure responsible for cardiorespiratory changes that occur following application of neurotransmitters and drugs to Schlaefke's area on the ventral medullary surface is the nucleus reticularis rostroventrolateralis (RVL), which is distinguished from adjacent regions of the reticular formation, in part, by the presence of adrenaline‐synthesizing neurons. To determine whether an equivalent adrenergic population is present in the RVL of the cat, we used antibodies raised against bovine adrenal PNMT to map the distribution of adrenaline‐synthesizing neurons in the reticular formation. In the ventrolateral medulla, we found that labeled cells extended from the level of the retrofacial nucleus to the calamus scriptorius. The majority of labeled cells were seen in a nucleus designated RVL at the level of the rostral one‐third of the inferior olive. In the dorsomedial medulla, cells were labeled in the caudal aspect of the nucleus tractus solitarii (NTS) and were especially dense in the subnucleus gelatinosus and commissural nucleus of the vagus. A few lightly labeled cells were also present in the rostral pole of the area postrema (AP). In contrast to the rat, few or no immunoreactive cells were found in the rostral NTS, medial longitudinal fasciculus, nucleus paragigantocellularis dorsalis, or periventricular gray. Our results are consistent with the notion that an area of the RVL containing adrenergic perikarya is the anatomical structure responsible for cardiovascular changes that occur when chemicals are applied to Schlafke's area.
Transient midline raphe glial structure in the developing rat
Authors: Van Hartesveldt Carol , Moore Blake , Hartman Boyd K. 
Published: January 2005

AbstractA major glial structure is present during development within the midline raphe of the midbrain, hindbrain, and cervical spinal cord of the rat. It is composed of great numbers of glial cell bodies lying immediately ventral to the cerebral ventricular system and the large radial processes extending from these cells toward the ventral surface of the brain roughly within the midsagittal plane. There is also a smaller group of glial cells on the dorsal surface of the aqueduct and the central canal whose processes extend to the dorsal surface of the brain. The entire structure exhibits an intensely positive immunoreactivity with the antibody to the S‐100 protein, a nervous‐system‐specific protein found primarily in the cytoplasm of astrocytes. This immunoreactivity makes possible a clear visualization of the extent, magnitude, and continuity of this structure from at least embryonic day 15, the first age examined, until postnatal days 7–8, when it is no longer visible by this technique.This glial structure has several prominent morphological characteristics. During prenatal and early postnatal development the fibers forming the ventral aspect of the structure in the midbrain and hindbrain are formed into two parallel plates on either side of the midline with S‐100‐negative tissue between the plates. As development progresses, S‐100‐positive fibers are continually added so that the plates become thicker at the expense of the nonstaining intervening area. By postnatal day 4 only a single midline plate of fibers is visible, occupying the entire midline raphe. In the region of the pontine flexure the entire structure takes on a distinctly pleated configuration. This fact produces a curious “sine wave” appearance when the plane of section crosses these vertical pleats. At postnatal day 5 the structure begins to disappear, and it is no longer visible by 7–8 days postnatal. This glial structure does not stain with antisera to glial fibrillary acidic protein, a protein associated with fibrous astrocytes, or routine cell stains such as cresyl violet. With these techniques the raphe area appears essentially devoid of identifiable cellular elements.
Granule cell development in the frog cerebellum during spontaneous and thyroxine‐induced metamorphosis
Authors: Hauser Kurt F. , Uray Nándor J. , Gona Amos G. 
Published: January 2005

AbstractGranule cell maturation in the cerebellum of bullfrog tadpoles was studied during both spontaneous and thyroxine‐induced metamorphosis by using electron microscopy and Golgi‐impregnated preparations. The production of cerebellar microneurons, a majority of which are granule cell precursors, was quantitatively compared during spontaneous and thyroxineinduced metamorphosis by using stereological methods and biochemical measurements of DNA.Granule cell migration and differentiation appeared morphologically similar during spontaneous and thyroxine‐induced metamorphosis. In both instances, granule cells (1) migrated tangentially along the pial surface, (2) migrated into the internal granular layer, (3) developed dendritic arbors, and (4) formed synaptic contacts with the processes of Golgi cells and with mossy fibers. These events are similar to developmental processes that have been described in detail in other animals. Quantitative stereological measurements demonstrated similar overall patterns of change during spontaneous and thyroxine‐induced metamorphosis. Most notably, increases in the volume of the external granule layer correlated with increases in the relative and total amounts of DNA. However, measurements of total DNA were consistently reduced during the period of accelerated change that occurs in thyroxine‐induced metamorphosis, although external granular layer volume was greater in these tadpoles after 2 and 3 weeks of thyroxine treatment than in spontaneously metamorphosing tadpoles. While granule cell development in the frog is largely dependent on thyroid hormone, differences between thyroid‐hormone‐induced and spontaneously metamorphosing tadpoles suggest that normal patterns of cerebellar development are also dependent on events that occur in premetamorphic tadpoles in the absence of thyroid hormone.
Morphology of motoneurons in different subdivisions of the rat facial nucleus stained intracellularly with horseradish peroxidase
Authors: Friauf Eckhard 
Published: January 2005

AbstractHorseradish peroxidase was injected into single facial motoneurons of the rat. Neurons were identified by antidromic stimulation of either the buccal or the marginal mandibular or the posterior auricular nerve branches. Motoneuronal cell bodies supplying the buccal branch were located in the lateral subdivision of the facial nucleus, those supplying the marginal mandibular branch were in the intermediate subdivision, and those supplying the posterior auricular branch were in the medial subdivision. Eleven motoneurons were reconstructed with a computer‐assisted technique. Their soma diameters averaged 20 μm; the average number of primary dendrites was 7.9 and the combined lengths of the dendritic trees averaged 17,650 μm. There was no distinction between the three motoneuron groups in terms of these and other quantitative data. However, on the basis of reconstructed dendritic tree orientation (i.e., dendritic distribution), major differences were observed between motoneurons of the three groups. Dendrites from all groups extended beyond the boundaries of the facial nucleus into the reticular formation. The border between the intermediate and the lateral subdivision was crossed by some dendrites but the overlap was small. In contrast, no dendrite of a motoneuron in the medial subdivision entered the intermediate subdivision and vice versa. The dendritic extent was totally restricted by the borders between these two subdivisions. Outside the Nissl‐defined nuclear border, however, dendrites from cells in adjacent subdivisions overlapped.It is concluded that the medial subdivision of the facial nucleus can be distinguished from the intermediate and lateral subdivisions not only by its sharp Nissl‐defined border but also by the discrete organization of its dendritic field.
A cholinergic projection to the rat superior colliculus demonstrated by retrograde transport of horseradish peroxidase and choline acetyltransferase immunohistochemistry
Authors: Beninato M. , Spencer R. F. 
Published: January 2005

AbstractAcetylcholinesterase (AChE) has been localized by histochemistry in the superior colliculus and in the tegmentum of the caudal midbrain and rostral pons of the rat. The pattern of AChE localization in the superior colliculus was characterized by homogeneous staining in the superficial layers and patchlike staining in the intermediate gray layer. In the tegmentum, AChE was localized in the pedunculopontine nucleus (PPN), beginning rostrally at the caudal pole of the substantia nigra and extending caudally to the level of the parabrachial nuclei, and in the lateral dorsal tegmental nucleus (LDTN) of the central gray. The localization of AChE in these nuclei overlapped the distribution of neurons stained by immunohistochemistry using an antibody to choline acetyltransferase (CHAT), the synthesizing enzyme of the neurotransmitter acetylcholine. Other neighboring areas that were stained with AChE, but that did not contain ChAT‐immunoreactive neurons, included the microcellular tegmental nucleus and the ventral tegmental nucleus.Neurons in the PPN and LDTN were determined to be potential sources of the cholinergic projection to the intermediate gray layer of the rat superior colliculus by double labelling with retrograde transport of horseradish peroxidase (HRP) combined with the immunohistochemical localization of ChAT. Three populations of neurons were identified. A predominantly ipsilateral ChAT‐immunoreactive population was located in the pars compacta subdivision of PPN (PPNpc). Retrograde HRP‐labelled neurons in the pars dissipata subdivison of the PPN (PPNpd), located ventral to the superior cerebellar peduncle (SCP) at the level of the inferior colliculus, composed a second population that was predominantly contralateral but was not ChAT immunoreactive. A third population of retrogradely labelled neurons was predominantly ipsilateral and ChAT immunoreactive and was located in the LDTN. These findings compared favorably with the full extent of the projection from this tegmental region revealed by retrograde transport of HRP from the superior colliculus when more compatible fixation and chromogen procedures were used.The results suggest that the PPN and the LDTN are two sources of the cholinergic input to the superior colliculus. Since the PPN also has extensive efferent, and afferent, connections with basal‐ganglia‐related structures, this cholinergic excitatory input to the superior colliculus, like the GABAergic inhibitory input from the substantia nigra pars reticulata, may provide the basis for an additional influence of the basal ganglia on visuomotor behavior.
Spatial segregation of synaptic inputs and outputs in a locust auditory interneurone
Authors: Peters Brian H. , Römer Heiner , Marquart Volker 
Published: January 2005

AbstractUsing intracellular injection of cobalt, processing for electron microscopy, and using on‐section silver intensification, we have investigated the distribution of synapses on the metathoracic arborization of the TN1 intersegmental interneurone in the auditory system of the locust. Previous studies have indicated that inputs to this neurone from tympanal afferents are spatially segregated from its outputs to higher‐order inhibitory interneurones. Branches in the area of input are characterised by a smooth appearance in Lucifer Yellow preparations, whereas branches in the main output area appear beaded. Sampling different areas of the TN1 arborization, we have found marked differences in the respective densities of input and output synapses. Labelled profiles in areas of beaded branching have an extremely high density of presynaptic sites, with a much smaller number of synaptic inputs. Smooth branches bear many input synapses, but we have found no output synapses on them. Our results indicate a good correlation between branch beading and presynaptic function and between smooth branches and postsynaptic function. These correlations enable us to predict synapse distribution on other insect neurones with a similar division in brach morphology and also extend our knowledge of the functioning of TN1 itself.
Diencephalic catecholamine neurons (A‐11, A‐12, A‐13, A‐14) show divergent changes in the aged rat
Authors: Selemon Lynn D. , Sladek John R. 
Published: January 2005

AbstractThe effects of aging on diencephalic (A‐11, A‐12, A‐13, A‐14) Catecholamine neurons in the F334 male rat were examined with Falck‐Hillärp histofluorescence. In contrast to the age‐related increase in A‐12 perikaryal fluorescence intensity previously reported (Hoffman and Sladek: Neurobiol, Aging 1:27–37, '80), incertohypothalamic perikarya showed decreased (A‐13) or unchanged (A‐11, A‐14) fluorescence intensity with age. Cell counts of fluorescent A‐12 perikarya disclosed a 47% increase in the number of fluorescent A‐12 neurons in 30‐month‐old F344 rats relative to the 3‐month‐old controls; numbers of A‐11 and A‐13 fluorescent perikarya decreased with age, but the declines were not statistically significant. It is unlikely that the age‐related increase in number of fluorescent A‐12 perikarya is the result of proliferation of neurons in the aged F344 rat. Rather, the greater number of fluorescent A‐12 perikarya in 30‐month‐old F344 rats indicates that some A‐12 neurons in 3‐month‐old F344 rats contain levels of dopamine that are subthreshold for detection with the Falck‐Hillärp fluorescence technique, whereas virtually all A‐12 perikarya in 30‐month‐old F344 rats contain detectable quantities of dopamine. These findings suggest that diencephalic catecholamine neurons exhibit divergent changes in transmitter content and cell number that may reflect varying degrees of functional integrity during brain aging.