bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histaminergic system in the cat hypothalamus with reference to type B monoamine oxidase
Authors: Lin J. S. , Kitahama K. , Fort P. , Panula P. , Denney R. M. , Jouvet M. 
Published: January 2005

AbstractIt is known that histamine (HA) and type B monoamine oxidase (MAO‐B), an enzyme involved in its metabolism, are present in the posterior hypothalamus, but the sites where MAO‐B intervenes in HA metabolism remain uncertain. The present study examined and compared the detailed distribution and morphology of neurons immunoreactive to HA (HA‐ir) and MAO‐B (MAO‐B‐ir) in the cat hypothalamus. HA‐ir neurons were localized almost exclusively in the posterior hypothalamus with the largest group in the tuberomammillary nucleus and adjacent areas. MAO‐B‐ir staining was detected in the vast majority of HA‐ir neurons, suggesting that the degradation of tele‐methylhistamine (t‐MHA), the direct metabolite of HA, may occur within these cells. Nevertheless, a few HA‐ir cells showed no detectable or very weak MAO‐B‐ir labeling; a small group of neurons containing MAO‐B alone was detected in the area dorsolateral to the caudal part of the arcuate nucleus. Numerous HA‐ir axons and terminal‐like structures were distributed unevenly in virtually all hypothalamic regions. One of their principal trajectories ascended through the ventrolateral part of the hypothalamus and rostrally formed an axon column, which ascended into the preoptic area and contributed fibers to the diagonal band of Broca and bed nucleus of the stria terminalis. Other HA‐ir axons passed laterally, dorsal to the zona incerta or ventrally through a narrow zone dorsal to the optic tract. Numerous long HA‐ir axons coursed dorsomedially from the ventrolateral posterior hypothalamus to the dorsal hypothalamic area. Many are oriented vertically to the thalamus in the midline. MAO‐B‐ir axons and fibers were detectable throughout the hypothalamus and overlapped the areas distributing HA‐ir fibers. They were, however, weaker in staining intensity and apparently fewer than the HA‐ir fibers. MAO‐B‐ir glial cells were numerous in all hypothalamic structures rich in HA‐ir fibers. These results suggest that the metabolism of t‐MHA may also occur within HA terminals and glial cells.
Synapses of extrinsic and intrinsic origin made by callosal projection neurons in mouse visual cortex
Authors: Czeiger David , White Edward L. 
Published: January 2005

AbstractNeurons in areas 17/18a and 17/18b of mouse cerebral cortex were labeled by the retrograde transport of horseradish peroxidase (HRP) transported from severed callosal axons in the contralateral hemisphere. Terminals of the local axon collaterals of labeled neurons (intrinsic terminals) were identified in the border regions of area 17 with areas 18a and 18b, and their distribution and synaptic connectivity were determined. Also examined were the synaptic connections of extrinsic callosal axon terminals labeled by lesion‐induced degeneration consequent to the severing of callosal fibers. A postlesion survival time of 3 days was chosen because by this time the extrinsic terminals were all degenerating, whereas the intrinsic terminals were labeled by horseradish peroxidase.Both intrinsic and extrinsic callosal axon terminals occurred in all layers of the cortex where, with rare exception, they formed asymmetrical synapses. Layers II and III contained the highest concentrations of intrinsic and extrinsic callosal axon terminals. Analyses of serial thin sections through layers II and III in both areas 17/18a and 17/18b yielded similar results: 97% of the intrinsic (1,412 total sample) and of the extrinsic (414 total sample) callosal axon terminals synapsed onto dendritic spines, likely those of pyramidal neurons; the remainder synapsed onto dendritic shafts of both spiny and nonspiny neurons. Thus, the synaptic output patterns of intrinsic vs. extrinsic callosal axon terminals are strikingly similar. Moreover, the high proportion of axospinous synapses formed by both types of terminal (97%) contrasts with the proportion of asymmetrical axospinous synapses that occurs in the surrounding neuropil where about 64% of the asymmetrical synapses are onto spines. This result is in accord with previous quantitative studies of the synaptic connectivities of callosal projection neurons in mouse somatosensory cortex, and lends additional weight to the hypothesis that axonal pathways are highly selective for the types of elements with which they synapse.
Aminergic and cholinergic afferents to REM sleep induction regions of the pontine reticular formation in the rat
Authors: Semba Kazue 
Published: January 2005

AbstractMicroinjection of cholinergic agonists in a dorsolateral part of the mesopontine tegmentum has been shown to induce a rapid eye movement (REM) sleep‐like state. Physiological evidence indicates that not only acetylcholine but also various amine transmitters, including those implicated in behavioral state regulation, affect neuronal activity in this region of the pontine reticular formation. In the present study, sources of select aminergic and cholinergic inputs to this REM sleep induction zone were identified and quantitatively analyzed by using fluorescence retrograde tracing combined with immunofluorescence in the rat.In addition to previously demonstrated cholinergic projections from the pedunculopontine and laterodorsal tegmental nuclei, the REM sleep induction zone received various aminergic inputs that originated in widely distributed regions of the brainstem and hypothalamus. Serotoninergic afferents represented a mean of 44% of all aminergic/cholinergic source neurons projecting to the REM sleep induction zone, which was comparable to the mean percentage of 39% represented by cholinergic afferent neurons. The serotoninergic afferents originated from the raphe nuclei at all brainstem levels, with heavier projections from the pontine than from the medullary raphe nuclei. Unexpectedly, an additional major serotoninergic input was provided by serotoninergic neurons in the nucleus prosupralemniscus (B9). Noradrenergic afferent neurons represented a mean of 14% of all aminergic/cholinergic source neurons, which was only about one‐third of the mean percentage of either cholinergic or serotoninergic source neurons. These noradrenergic projection neurons were located not only in the locus ceruleus (8%) but also in the lateral tegmentum, including the A5 (4%) and A7 (2%) cell groups. Histaminergic neurons in the tuberomammillary hypothalamic nucleus represented a minor group of afferent neurons (3%), and a still smaller input came from adrenegic C1 neurons. The pattern of these transmitter‐specific afferent connections appeared to be similar regardless of the longitudinal level within the REM sleep induction zone.The present results are consistent with previous behavioral and physiological evidence for a role of the pontine REM sleep induction zone in triggering REM sleep. The regulation of REM sleep induction would be best understood in terms of a state‐dependent interplay of cholinergic, serotoninergic, and other inputs all acting convergently upon neurons in the REM sleep‐inducing region of the pontine reticular formation.
Morphological correlates of functional recovery in the chicken inner ear after gentamycin treatment
Authors: Duckert Larry G. , Rubel Edwin W 
Published: January 2005

AbstractNewly hatched chickens were allowed to survive 6, 10, 15, and 20 weeks after 10 days of gentamycin sulfate treatment. Ultrastructural studies of hair cells and nerve terminals in the auditory receptor organ, the basilar papilla, were carried out with transmission and scanning electron microscopes. Attention was paid to absolute sensory cell (hair cell) numbers, stereocilia maturity and orientation, and reinnervation within a band 100 μm wide centered 1,100 μm from the basal end of the avian cochlea.Sensory cell numbers were equivalent to those of untreated control animals within the study area in the earliest survival group. Both immature and mature appearing hair cells were identified throughout the recovery period. However, the ratio of mature to immature hair cells gradually increased to exceed 95% at 20 weeks. Stereocilia bundle reorientation also occurred throughout the study period. Orientation was often abnormal at 6 weeks, but by 20 weeks more than 95% of the regenerated hair cells were aligned within normal limits established in the control ears. Hair cell differentiation occurring at 10–15 weeks was associated with degeneration of the afferent nerve receptor complexes commonly observed in 6 week survivors. These complexes were replaced by one or two small bouton shaped efferent terminals per cell. At 20 weeks, two or three chalice shaped vesiculated terminals were observed per cell in both the gentamycin treated and control ears.On the basis of these observations normal physiological activity would be predicted at 20 weeks following gentamycin treatment, at which time sensory cell repopulation, maturation, reorientation, and innervation approximates the normal anatomical condition. © 1993 Wiley‐Liss, Inc.
Transcellular labeling by dil demonstrates the glossopharyngeal innervation of taste buds in the lingual epithelium of the axolotl
Authors: Nagai Takatoshi 
Published: January 2005

AbstractInnervation of the axolotl lingual epithelium by the glossopharyngeal nerve was examined to reveal its sensory target cells. The carbocyanine dye diI was applied to the nerve stump in the tongue fixed with paraformaldehyde. After a diffusion period of several months, the tongues were examined with a conventional epifluorescence microscope and a confocal laser scanning microscope (LSM) in wholemounts or preparations sectioned with a vibratome. Beneath the epithelium the labeled nerve fibers spread horizontally to form a meshwork of fibers, from which fascicles of fibers extended upward perpendicularly to the epithelium to innervate taste buds. Numerous taste buds were labeled by possible transcellular diffusion of diI. At the base of the taste bud, the nerve fibers branched and formed a basal plexus of fine fibers, on which numerous varicosities were seen. One or at most several taste cells were labeled in a taste bud. In the basal part of taste buds, the cell without an apical process, the basal cell, was also labeled. In the epithelium, between the taste buds, a few solitary cells were labeled. In some cases, a single fascicle of fibers innervating these cells was clearly shown by the LSM. In addition, fine fibers apparently formed free nerve endings in the epithelial cell layer. The results showed that the IX nerve innervated not only taste cells, but also presumed mechanosensory basal cells in the taste bud and the solitary cells of unknown function in the non‐taste lingual epithelium. Afferent nerve responses to mechanical stimulation of the tongue may be explained by these non‐taste cellular elements in the epithelium. © 1993 Wiley‐Liss, Inc.
Distribution of choline acetyltransferase immunoreactivity in the brain of the lizard Gallotia galloti
Authors: Medina Loreta , Smeets Wilhelmus J. A. J. , Hoogland Piet V. , Puelles Luis 
Published: January 2005

AbstractThe aim of the present study is to provide a complete description of the distribution of choline acetyltransferase (ChAT) immunoreactivity (i) in the brain of the lizard Gallotia galloti, on the basis of two different primary antisera: rat anti‐ChAT and rabbit anti‐chicken ChAT. Considering that the brain is a segmented structure, we have analysed our data with respect to transverse segmental domains (or neuromeres), which have been previously described by several authors in the brain of vertebrates.In the telencephalon, ChATi neurons are seen in the cortex, anterior dorsal ventricular ridge, basal ganglia, diagonal band, and bed nucleus of the stria terminalis. Further caudally, ChATi cell bodies are located in the preoptic area, hypothalamus, habenula, isthmus, and all motor efferent centers of the brainstem and spinal cord.Plexuses of ChATi fibers are observed in the areas containing cholinergic cell bodies. In addition, distinct plexuses are found in the cortex, the posterior dorsal ventricular ridge, the neuropiles of all primary visual centers of the diencephalon and mesencephalon, and several non‐visual nuclei of the brainstem.The distribution of ChAT immunoreactivity in the brain of G. galloti resembles in many respects that of other vertebrates, and differences are mainly observed in the pretectum and midbrain tectum. Transverse segmental domains were identified in the brainstem and forebrain of Gallotia when the cranial nerve roots and fiber tracts were used as a reference, and most cranial motor nuclei were found to occupy the same segmental positions as have been reported in the chick. © 1993 Wiley‐Liss, Inc.
Interlaminar connections of the superior colliculus in the tree shrew. I. The superficial gray layer
Authors: Hall William C. , Lee Psyche 
Published: January 2005

AbstractOne of the most persistent problems in the study of the superior colliculus is the relationship between its superficial and deep layers. The superficial tier of layers is considered to be visuosensory in function, whereas the deep tier is multisensory and has premotor functions. This fundamental distinction is the primary basis for the view that a visually triggered shift in the direction of gaze depends on the transfer of information from sensory cells in the superficial tier to premotor cells in the deep tier. The goal of the present experiments was to examine the interalaminar projections of the superficial gray layer in the tree shrew Tupaia belangeri. We used biocytin as the marker for tracing the pathways. The tree shrew was chosen because its large and distinctly laminated superior colliculus facilitates the task of examining connections between the layers. Biocytin was used because of its sensitivity and because it allowed us to place very small injections restricted entirely to the superficial gray layer. The results demonstrated that a prominent pathway originates in the superficial gray layer and terminates in stratum opticum. In comparison, the projection from the superficial gray layer to the layers beneath stratum opticum is extremely sparse. The pathway from the superficial gray layer to stratum opticum has a columnar distribution, extending about 100 m̈m rostrally and caudally from the center of the injection site. There were no signs of more remote intracollicular connections, nor of patches or bands of terminals. The biocytin injection sites also labeled pathways to nuclei as distant from the superior colliculus as the diencephalon, including the dorsal and ventral lateral geniculate bodies, and the pulvinar. The results suggest that stratum opticum may serve as a link between the superficial gray layer and the deeper layers. © 1993 Wiley‐Liss, Inc.
Contact‐spacing among astrocytes is independent of neighbouring structures: In vivo and in vitro evidence
Authors: Tout Simon , Dreher Zofia , Chan‐ling Tailoi , Stone Jonathan 
Published: January 2005

AbstractWe have examined the morphology of astrocytes and the arrays they form in two situations, in retinas from which ganglion cells and blood vessels have been caused to degenerate, and in vitro. These observations were made to test whether the regularity of the spacing of astrocytes within normal central nervous tissue results from interaction among astrocytes, or from interaction between astrocytes and other elements of that tissue. Both in the partially degenerated cat retina, and in cultures of astrocytes from neonatal rat cortex, astrocytes make and maintain contact with neighbouring astrocytes, yet space their somas apart, giving regularity to the arrays. These results support the hypothesis that the regularity observed in arrays of astrocytes in intact tissue results from an interaction among astrocytes, independent of neighbouring structures, and lead us to suggest that the cell‐cell interactions involved in contact spacing serve to distribute astrocytes through the central nervous system, and may, in other tissues, underlie the formation of epithelia. © Wiley‐Liss, Inc.
Spatial distributions of chemically identified intrinsic neurons in relation to patch and matrix compartments of rat neostriatum
Authors: Kubota Yoshiyuki , Kawaguchi Yasuo 
Published: January 2005

AbstractThe spatial distributions and dendritic branching patterns of chemically identified subpopulations of striatal intrinsic neurons, defined by immunoreactivity for choline acetyltransferase (ChAT), neuropeptide Y or parvalbumin, were studied in relation to patch and matrix compartments of rat neostriatum. ChAT‐immunoreactive cells and fibers showed an uneven pattern of distribution in the striatum. ChAT immunoreactivity was higher in the dorsolateral part and lower in the ventromedial part of the striatum. This regional gradient pattern is the inverse of the overall pattern of calbindin D28k immunoreactivity. However, in small regions close to the lateral ventricle and globus pallidus, areas containing fewer ChAT‐immunoreactive cells and fibers coincided with those containing low calbindin D28k immunoreactivity. Neuropeptide Y immunoreactivity was uniform in the neostriatum. Certain neuropeptide Y cells (about 20%) were also immunoreactive for calbindin D28k, indicating that at least a small population of calbindin D28k‐immunoreactive cells are medium aspiny cells. Parvalbumin immunoreactivity was not uniform in the striatum. A higher density of parvalbumin immunoreactivity was found in the neuropil in lateral and caudal parts than in the medial part. Small regions with weaker parvalbumin‐immunoreactive neuropil partially corresponded to calbindin D28k poor patches. Larger cells immunoreactive for parvalbumin were preferentially located in lateral and caudal parts of the striatum.Cells immunoreactive for ChAT, neuropeptide Y or parvalbumin showed basically similar distribution patterns in relation to the patch and matrix compartments. Most stained cells were located in the matrix, but some were located at the borders of patches and a few were inside patches. Most primary dendrites of stained cells in the matrix or patches remained confined to these compartments, but cells on the borders invariably extended dendrites into both compartments. The striatal intrinsic neurons form chemically differentiated neuronal circuits within the matrix, and the patches and those whose dendrites cross the borders may contribute to associational interconnections between the two compartments, unlike the spiny projection neurons whose dendrites are confined to one or the other compartment. © Wiley‐Liss, Inc.
Pre‐ and postnatal development of the primary visual cortex of the common marmoset. II. Formation, remodelling, and elimination of synapses as overlapping processes
Authors: Missler Markus , Wolff Annelies , Merker Hans‐Joachim , Wolff Joachim R. 
Published: January 2005

AbstractDuring ontogenesis changes in the numerical density of synapses are usually assumed to depend essentially on variations in the formation of synapses. Only the final adjustment to adult synapse densities is thought to include the elimination of synapses in some brain regions of certain species. Here, we focus attention on quantitative aspects of synapse elimination throughout development of area 17 of marmoset monkeys (Callithrix jacchus). Mature synapses, various precursor forms, and indicators of lysosomal degradation of synapses were quantitatively analysed by electron microscopy and morphometric methods. A total number of about 135 × 109 synapses was calculated for area 17 in each adult hemisphere corresponding to a volume density of 600 × 106 synapses/mm3. At 3 months of age, the respective values were 508 × 109/area and 1,159 × 106/mm3, while at birth these values were 69 × 109/area and 328 × 106/mm3. Consequently, at least three out of four synapses are eliminated between 3 months and adulthood. However, the real number of synapses being eliminated during development is probably much larger if the time course of lysosomal degradation is additionally taken into account. The frequency of lysosomes in presynaptic endings is highest before net‐elimination of synapses occurs, i.e., between 1 and 3 months. This suggests that lysosomal degradation is not directly responsible for the majority of synapses removed during ontogenesis but apparently represents a second mechanism for synapse remodelling and elimination. Thus, it appears from this study that remodelling and elimination of synapses are quantitatively as important as their formation, and accompany synaptogenesis from its very onset onwards. © 1993 Wiley‐Liss, Inc.
A biphasic sequence of myelination in the developing optic nerve of the frog
Authors: Playford D. E. , Dunlop S. A. 
Published: January 2005

AbstractWe have examined the sequence of myelination along the optic nerve of the frog Litoria (Hyla) moorei from early tadpole life to adulthood. Myelinated axons were counted in electron micrographs of transverse sections taken from behind the eye, at the optic foramen and the chiasm. In tadpoles, myelinated axon numbers were significantly higher at the foramen than at the other levels. By metamorphic climax, numbers had risen at all three levels but more so behind the eye and at the chiasm to become approximately equal along the nerve. After metamorphosis, there was a dramatic increase in myelinated axon numbers, but another pattern was seen; in frogs of 5 cm and 7 cm body length, counts were significantly higher at the chiasm than at the foramen and lowest behind the eye. Thereafter, myelinated axon numbers stabilized at the chiasm but increased behind the eye and at the foramen so that in the most mature stage for this species, 9 cm adults, counts were again similar at the three levels. In addition, total axon numbers, that is, myelinated plus unmyelinated, were assessed from electron micrographs and increased from approximately 8,500 in early tadpoles to 0.65 million in fully mature adults. The proportion of axons that were myelinated showed two peaks, one before and the other after metamorphosis. Measurements of axon diameters from electron micrographs suggested that there was a critical diameter for myelination of 0.3 μm before, and of 0.5 μm after metamorphosis.The data indicate that there is a biphasic sequence of myelination of optic axons, the first phase being pre‐metamorphic and the second post‐metamorphic. The first phase is initiated at the foramen, and then extends both towards the eye and chiasm and continues until metamorphic climax. During the second phase, myelination originates at the chiasm, spreads towards the eye, and is complete only in the most mature adults. The critical diameter for myelination is smaller in the first phase than in the second. © 1993 Wiley‐Liss, Inc.
Developmental expression of a synaptic ribbon antigen (B16) in mouse retina
Authors: Bachman Katherine M. , Balkema Grant W. 
Published: January 2005

AbstractWe investigated the developmental expression of the synaptic antigen B16 in the outer and inner plexiform layers in the retina. We compared the expression of this protein with published accounts of retinal ribbon synaptogenesis. The time course of B16 expression was found to be similar, if not identical, to the time course of synaptogenesis in the photoreceptor terminal, supporting our idea of the synaptic nature of the B16 protein. This study provides further evidence which suggests that the B16 antigen is a ribbon associated protein. The morphology, location, and developmental expression of this antigen is coincident with the structure and development of the ribbon synaptic elements located in both the photoreceptor and bipolar terminals.The emergence of the B16 protein was also examined in retina from mice homozygous for the retinal degeneration (rd) mutation which affects photoreceptor synaptogenesis. The B16 expression in the rd retina paralles that in the wild‐type retina at early stages of development. However, significant changes in the morphology and staining pattern of the B16 antigen in the rd retina occurring at later postnatal stages are consistent with the degeneration observed in the photoreceptor terminals. © 1993 Wiley‐Liss, Inc.