bluuebunny/crossref_metadata_2025_split huggingface dataset:
Species differences in hippocampal commissural connections: Studies in rat, guinea pig, rabbit, and cat
Authors: van Groen Thomas , Wyss Michael 
Published: January 2005

AbstractThe tritiated amino acid autoradiographic method was employed to characterize the patterns of commissural projections originating in the hippocampus of the rat, guinea pig, rabbit, and cat. The results demonstrate that significant differences between species are present despite the overall similarity of the projections. In the rat and cat the commissural connections are widely distributed along the septotemporal axis of the hippocampus, but in the guinea pig and rabbit they are less widely distributed along this axis. Second, within the hippocampus proper the radial distribution of the commissural projection is species specific. In the rat, CA3 commissural projections are present in both the strata oriens and radiatum, but the densest projection is to the stratum oriens. In the guinea pig the radial distribution of this projection is similar to that observed in the rat, but in the rabbit the projection is almost entirely confined to the stratum oriens. In contrast, in the cat the CA3 commissural projection is very dense to the stratum radiatum and sparse to stratum oriens. An analysis of the relative density of label in the molecular layer of the fascia dentata suggests that the density of the commissural projection from CA4 is much greater in the rat and cat than in the guinea pig or rabbit. These results indicate that care must be exercised in the generalization of connectional data between species. The results also suggest a possible explanation for differences observed in the electrophysiology of these connections between species.
Chemosensory anterior dorsal fin in rocklings (GaidropsarusandCiliata, teleostei, Gadidae): Somatotopic representation of the ramus recurrens facialis a revealed by transganglionic transport of HRP
Authors: Kotrschal Kurt , Whitear Mary 
Published: January 2005

AbstractThe anterior dorsal fin in rocklings consists of a fringe of 50–80 delicate, vibratile rays, which are densely beset with epidermal chemosensory cells. The innervation of these cells is from the dorsal branch of the recurrent facial nerve, which also innervates all other fins and the skin of the trunk. This nerve carries at least three classes of fibres: small (0.5–1.5 μm in diameter), medium (1.5–4 μm), and large (>4 μm). Approximately 12,000 small and weakly myelinated nerve fibres from the recurrent facial nerve innervate the anterior dorsal fin organ. Application of HRP at different locations of the recurrent facial nerve labelled three different sizes of sensory perikarya within the geniculate ganglion–small (6–15 μm in diameter), medium (18–24 μm), and large (>25 μ)–which corresponds to the different size classes of fibres present within the nerve. Retrograde transganglionic transport of HRP revealed somatotopy within the brainstem facial lobe: the delicate nerve fibres innervating the chemosensory anterior dorsal fin terminate exclusively in a distinct, dorsal portion of the facial lobe. Fibres innervating the posterior dorsal fin, the anal and caudal fins, as well as the skin of the trunk terminate within caudal and dorsal areas of the ventral facial lobe; pectoral and pelvic fins are represented in the ventral and caudal portions of the ventral facial lobe. Innervation by a distinct type of fibre and exclusive representation within a distinct, dorsal part of the facial lobe may indicate a peculiar biological role in the anterior dorsal fin chemosensory organ in the rocklings.
Aberrant optic axons in the retinal pigment epithelium during chick and quail visual pathway development
Authors: Halfter Willi 
Published: January 2005

AbstractExamination of a large number of retinal pigment epithelia revealed that, in a small proportion, optic axons in chick and quail eyes aberrantly entered the pigment cell layer between embryonic day (E) 7 to E14. The aberrant retinal axons originated from the main stream of retinal fibers in the optic nerve and invaded the pigment layer from various positions of the optic nerve head or fissure by growing along the basal side of the pigment epithelium. The axon bundles grew several millimeters into the epithelial sheet and arborized at the margin of the eye. As shown by electron microscopy the nerve fibers occurred as bundles of three to several hundred axons. They always were located at the basal side of the epithelium, and were enveloped by processes of epithelial cells. Very large bundles of axons, however, displaced the epithelial cells from the basal matrix. These retinal axons contacted the pigment epithelial basal lamina. The basal extracellular matrix from the retinal pigment epithelium was isolated and used as substratum for in vitro cultures of various types of neural explants. The matrix preparations consisted of a sheet of a 50 nm thick basal lamina with a central lamina densa, two laminae rarae, and a 15 μm thick stroma. Axons from avian retina explants, as well as sensory ganglia, grew on the basal lamina side of the pigment cell matrix with the same growth rate and with the same fiber density as on similarly prepared basal laminae from the neural retina. These experiments show that the matrix from the pigment epithelium of the avian eye does not have negative effects on axonal growth and indicate that a basal lamina from a normally non‐innervated tissue can provide a favorable matrix for axonal growth.
Immunohistochemical localization of neuropeptides in the vocal control regions of two songbird species
Authors: Ball Gregory F. , Faris Patricia L. , Hartman Boyd K. , Wingfield John C. 
Published: January 2005

AbstractImmunohistochemistry was used to map the distribution of four neuropeptides in song control regions of two songbird species, the European starling (Sturnus vulgaris) and the song sparrow (Melospiza melodia). We searched for positively stained cell bodies or apparent terminals containing vasoactive intestinal peptide (VIP), methionine‐enkephalin (MET), cholecystokinin (CCK), and substance P (SUB P). Intraventricular colchicine pretreatment was administered to enhance the visualization of peptide‐containing cell bodies. Four areas implicated in the central control of song were examined. Three of these areas are sexually dimorphic telencephalic nuclei characteristic of songbirds: the caudal nucleus of the ventral hyperstriatum (HVc), the robust nucleus of the archistriatum (RA), and the magnocellular nucleus of the anterior neostriatum (MAN). The fourth region is the mesencephalic nucleus intercollicullaris (ICo), common to all birds, which contains the dorsomedial nucleus (DM) that appears to be specifically involved in the motor control of song.The pattern of neuropeptide localization was similar between the two species. However, the neuropeptides were heterogeneously dispersed among the four areas. VIP and MET were the most widely distributed, whereas CCK and SUB P were seen only in DM. MAN and HVc revealed remarkably similar patterns of staining for both MET and VIP. Fine varicosities immunolabeled for both these peptides appear to encircle nonreactive somata. In both these nuclei positively stained somata were observed for MET but not for VIP. In RA there was a dense accumulation of MET‐positive multipolar cell bodies. VIP‐containing neurons were seen in the surrounding archistriatum and caudal neostriatum but not in RA itself. Cell bodies and fibers for all four peptides were observed in DM; in no case were they limited to this subregion, but rather seemed to encompass the surrounding intercollicular area as well. The widespread distribution of VIP and MET strongly suggests a role for these peptides in the acquisition or production of passerine song.
Cortical connections of electrophysiologically and architectonically defined subdivisions of auditory cortex in squirrels
Authors: Luethke L. E. , Krubitzer L. A. , Kaas J. H. 
Published: January 2005

AbstractMultiunit recordings with microelectrodes were used to identify and delimit subdivisions of auditory cortex in squirrels. In the same animals, cortical connections of subdivisions of auditory cortex were determined by placing injections of the tracer wheat germ agglutinin conjugated with horseradish peroxidase (WGA‐HRP) into electrophysiologically defined locations. The electrophysiological results and patterns of connections were later related to myeloarchitectonic distinctions in brain sections cut parallel to the surface of the artificially flattened cortex. As previously described (Merzenich et al.: J. Comp. Neurol 166:387–402, '76), a primary auditory field, A‐I, was characterized by (1) neurons narrowly tuned to tone frequency; (2) a tonotopic map with high frequencies, which represented caudal to low frequencies; and (3) dense myelination. A‐I was reciprocally connected with a rostral field, R, a parietal ventral somatosensory representation, PV, cortex ventral to A‐I, and other nearby regions of cortex of the same hemisphere. Callosal connections of A‐I were with A‐I, R, and two or more other regions of temporal cortex. The less densely myelinated rostral field, R, also had neurons that were frequency tuned, but the neurons were often less securely driven. R appeared to have a tonotopic organization that roughly mirrored that of A‐I. Ipsilateral connections of R included A‐I, PV, and cortex ventral and caudal to R. Callosal connections were with R, A‐I, PV, and other locations in temporal cortex. Cortex in caudal PV, ventral to A‐I, and ventral to R was responsive to auditory stimuli, but responses to pure tones were weak and inconsistent, and habituation to a repeated stimulus was rapid. The cortex responsive to auditory stimuli included some but not all of the cortex connected with A‐I and R. The results lead to the conclusion that auditory cortex of squirrels contains at least two tonotopically organized fields, possibly as many as five or more auditory fields, and at least two auditory‐somatosensory fields.
Catecholamine‐synthesizing neuronal projections to the nucleus tractus solitarii of the rat
Authors: Thor Karl B. , Helke Cinda J. 
Published: January 2005

AbstractThe objective of the present study was to determine the location of the neurons that give rise to catecholamine‐containing terminals in the nucleus tractus solitarii. This was done by injecting rhodamine‐filled latex microspheres into the nucleus tractus solitarii of rats to retrogradely label neuronal cell bodies and by processing sections from the brains of these animals to determine if the labelled neurons were immunoreactive for the catecholamine‐synthesizing enzymes, dopamine‐beta‐hydroxylase (DBH) and phenyl‐ethanolamine‐N‐methyl transferase (PNMT).Approximately 60% of the DBH‐immunoreactive neurons that projected to the nucleus tractus solitarii belonged to the A1/C1 cell group, while an additional 20% belonged to the A5 cell group. Thus, these two ventrolateral rhombencephalic cell groups accounted for nearly 80% of the total number of rhodamine‐bead‐labelled DBH‐immunoreactive neurons in this series of experiments. Only a small number of DBH‐immunoreactive neurons of the A2/C2 cell group contained rhodamine‐filled latex microspheres. Rarely, DBH‐immunoreactive neurons in the locus coeruleus and the nucleus subcoeruleus were found to project to the nucleus tractus solitarii.The majority of the PNMT‐immunoreactive neurons that projected to the nucleus tractus solitarii belonged to the C1 cell group. Only small numbers of PNMT‐immunoreactive neurons of the C2 and C3 groups were found to contain rhodamine‐filled latex microspheres.It is concluded that neurons in the ventrolateral medulla and pons, some of which presumably utilize norepinephrine and/or epinephrine as a transmitter, could regulate autonomic function via direct projections to the nucleus tractus solitarii.
Calcitonin gene‐related peptide (CGRP) in the human spinal cord: A light and electron microscopic analysis
Authors: Harmann P. A. , Chung K. , Briner R. P. , Westlund K. N. , Carlton S. M. 
Published: January 2005

AbstractThe distribution of CGRP immunoreactivity in the cervical, thoracic, lumbar, and sacral levels of the human spinal cord was mapped at the light microscopic level with the aid of a rabbit‐generated antiserum against human calcitonin gene‐related peptide (CGRP). CGRP‐positive fibers formed a dense plexus in lamina I, II, the reticulated region of lamina V, and the tract of Lissauer at all spinal cord levels. The distribution of fibers showed some variations dependent on the cord level analyzed. At the light microscopic level, intervaricose fiber diameters consistantly measured 1.0 μm or less, and two types of CGRP varicosities were observed: a small (1 to 2 μm in diameter), relatively round profile and a larger, (3 to 4 μm in diameter) oval or oblong profile. At the electron microscopic level, immunostained varicosities contained a mixture of round clear vesicles and vesicles that contained dense cores. The CGRP immunoreaction product was often associated with vesicles containing dense cores. The reaction product was also seen associated with clear round vesicles or in the cytoplasmic matrix. Postsynaptic elements included dendritic spines, small and large diameter dendritic shafts and vesicle containing profiles. The presence of CGRP in the superficial dorsal horn of human spinal cord is highly suggestive of a role in primary afferent transmission as postulated in lower vertebrates. This study establishes the distribution of CGRP at four different spinal levels in human cord and will serve as a basis for future studies related to the pathologic conditions affecting sensory systems.
Medial gastrocnemius motor nucleus in the rat: Age‐related changes in the number and size of motoneurons
Authors: Hashizume Ken , Kanda Kenro , Burke Robert E. 
Published: January 2005

AbstractThe age‐related alterations in the number and size of alpha‐ and gamma‐motoneurons were studied in the medial gastrocnemius (MG) motor nuclei in rats at four ages: young (5 months), middle aged (10–13 months), old (26 months), and very old (31 months). Small volumes (0.1–0.5 μl) of 40% horseradish peroxidase (HRP) solution were injected into the cut MG nerve bilaterally by using glass micropipettes and a pressure injection system. The number, position, and soma size (average soma diameter) of MG motoneurons were determined by using photographic maps of each TMB‐stained section. The total number of myelinated axons was counted in seven MG nerves from the same animals.The average soma diameters in each MG nucleus were distributed bimodally; cells with average diameter greater than 21.0–24.0 μm were presumed to be alpha‐motoneurons and those with smaller diameters were presumed to be gamma. The mean number of presumed alpha‐motoneurons was significantly less in the old and very old groups as compared with the young and middle‐aged. In contrast, the number of presumed gamma‐motoneurons was the same across age groups. The mean average soma diameter of both alpha‐ and gamma‐motoneurons was smaller in the old animals. The apparent decrease in the total number of labeled motoneurons in old animals was also reflected in a decrease in myelinated axon counts. We conclude that there is a significant decrease in the absolute numbers of motoneurons in rats aged 26 months and older, with most of the decrease occurring among the larger alpha‐motoneurons.
Immunohistochemical and in situ hybridization analysis of the development of the rat somatostatin‐containing neocortical neuronal system
Authors: Naus C. C. G. , Miller F. D. , Morrison J. H. , Bloom F. E. 
Published: January 2005

AbstractThe chemical differentiation of somatostatin (SS) neurons in rat neocortex was characterized by molecular biochemical and morphological methods. Northern (RNA) blotting indicates that regional distribution of SS mRNA correlates with the known distribution patterns of SS‐containing neurons in the adult, while similar analysis of poly (A)+ RNA isolated from telencephalon at various times postnatally shows an increase between P9 and P15, with a slight decrease in the adult. In situ hybridization with a probe specific to SS mRNA, and immunohistochemistry using antisera specific for the N‐terminally extended form of SS, SS28, and SS28(1–12), were used to detect neocortical neurons containing this mRNA or its translation product. The appearance of SS mRNA is coincident with detectable immunoreactivity for SS peptides. The expression of the SS gene by cortical neurons occurs in two waves. From P1 to P11, hybridizing neurons are predominant below the cortical plate in the developing infragranular layers. Immunohistochemical analysis of immunoreactivity to SS28 reveals a significant development of this neocortical system by late gestation (E20). At this point SS28(1–12), the predominant SS form detected, is mainly in neurons of the subplate, with less detectable immunoreactivity in the intermediate zone and cortical plate. By P2, neurons in the subplate exhibit detectable SS28 and SS28(1–12). Although immunoreactive perikarya are no longer detectable at P2 in the cortical plate or marginal zone, a very dense plexus of SS28(1–12) fibers is seen in the subplate, marginal zone, and intermediate zone; relatively few immunoreactive fibers are found in the cortical plate. By P12, a dramatic shift occurs; a large supragranular population of these SS neurons is observed by both mRNA and antibody methods, as is a subsequent decrease in number in the adult. The shift in immunoreactivity occurs with supragranular SS28‐containing neurons now prominent, and SS28(1–12)‐containing neurons and fibers greatly diminished. The number of neurons containing SS mRNA or SS28 immunoreactivity decreases from P12 to adult, when these neurons exhibit a bilaminar distribution. Neurons immunoreactive for SS28(1–12) are now sparsely distributed throughout the cortex, while SS28(1–12) fibers densely innervate layers I and V/VI.
Afferent innervation of outer hair cells in adult cats: II. Electron microscopic analysis of fibers labeled with horseradish peroxidase
Authors: Simmons D. D. , Liberman M. C. 
Published: January 2005

AbstractOuter spiral fibers (OSFs) were retrogradely labeled with injections of horseradish peroxidase. After the peripheral arborization patterns were reconstructed at the light microscopic level (Simmons and Liberman, '88), restricted regions of selected fibers were analyzed via electron‐microscopic reconstruction of serial sections. The ultrastructural data in the present study suggested that the contact between the outer hair cell (OHC) and the terminal swellings of OSFs corresponds to the afferent synapse described in numerous other ultrastructural studies. The en passant swellings that contacted OHCs also appeared to be points of synaptic contact. However, en passant synapses were not always associated with a swelling of the OSF at the point of contact: thus, the light‐microscopic reconstructions probably underestimate the numbers of synapses. OSF branches terminating well below the OHCs were seen to end most commonly in intimate contact with the Deiters' cells. Membrane specialization was occasionally seen at this point of contact; however, the specialization was sufficiently undifferentiated to preclude identification.
GABAergic elements in the neuronal circuits of the monkey neostriatum: A light and electron microscopic immunocytochemical study
Authors: Pasik Pedro , Pasik Tauba , Holstein Gay R. , Hámori Jozsef 
Published: January 2005

AbstractAn antibody raised in rabbits against a GABA‐BSA conjugate was used together with the PAP technique to label elements in the neostriatum of three Old World monkeys. Light microscopy revealed numerous immunoreactive medium‐size neurons of various staining intensities, some of which had indented nuclei, as well as an occasional large cell. The neuropil showed a plexus of fine processes with frequent puncta, Ultrastructurally, the medium‐size GABA‐positive neurons were of two types: one with smooth nuclei and scanty cytoplasm, similar to spiny I cells, the other with invaginated nuclear envelopes and more abundant perikaryon, resembling the aspiny type. Correspondingly, labeled dendrites were either spiny or varicose. Some stained axons were myelinated, and the boutons had either large and ovoid, or small and pleomorphic vesicles. All of these boutons formed symmetric synapses, the former type with GABA‐positive dendritic shafts but also with unlabeled dendrites; the latter type usually with GABA‐negative elements, either dendrites, dendritic spines, or somata. Synapses were also observed between unreactive boutons and immunostained dendrites. Terminals with densely packed, small round vesicles that established asymmetric synapses with spines were always GABA‐negative. Glial elements were consistently unlabeled, save, for some astroglial endfeet. These findings provide positive evidence for the existence of two classes of GABAergic striatal neurons corresponding to a long‐axoned spiny I type and an aspiny interneuron. Furthermore, the simultaneous labeling of GABA‐immunoreactive presynaptic and postsynaptic profiles offers possible morphologic bases for the various kinds of intrastriatal inhibitory processes, including the feedforward, feedback, and “autaptic” types.
Ultrastructural study on the meninx of the goldfish brain
Authors: Momose Yoshiaki , Kohno Kunio , Ito Ryuzo 
Published: January 2005

AbstractThe cranial meninges of the goldfish were studied by means of transmission electron microscopy combined with the freeze‐fracturing technique. The goldfish has three cranial meninges. The outer layer consists of flattened cells, which are stratified in 3 to 7 layers and are packed densely with many interdigitations of cell processes. The constituent cells in the outer layer have copious smooth endoplasmic reticulum and are joined by gap junctions but have no desmosomes. The intermediate layer is thin, continuous, and single cell. In the replicas, both the upper and the lower surfaces of the intermediate layer cells have numerous openings of pinocytotic vesicles, but the upper surface is characterized by round gap junctions, whereas the lower surface is identified by a linear continuation of a combination of tight junctions and gap junctions and by desmosomes. The lateral surface has a hexagonal network of tight junctions and gap junctions with internally located desmosomes, which functions as a barrier to intercellular movement of lanthanum. The inner layer consists of a meshwork of reticular cells and large intercellular spaces, in which fine granular material, capillaries, and different types of blood‐derived free cells can be found. Cells in the inner layer contain rough endoplasmic reticulum stacked in lamellae and have irregular processes joined by desmosomes. The goldfish meninges are compared with the meninges of mammals.