bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topological link‐vertex analysis of the growth of purkinje cell dendritic trees in normal, reeler, and weaver mice
Authors: Sadler M. , Berry M. 
Published: January 2005

AbstractThe growth of Purkinje cell dendritic trees in normal, reeler, and weaver mice has been defined by using Link‐Vertex Analysis. Growth probably occurs in three phases in normal and cortically located reeler trees. Phase I, completed by 7 days postnatum (dpn), establishes a rudimentary tree of 100 segments by random terminal branching. Phase II lasts from 7 to 20 dpn when some 690 and 450 segments are generated in normal and cortical reeler trees respectively. Phase II is initiated by an inductive stimulus mediated by a finite number of parallel fibres. Thereafter, dendritic trees develop a similar topology in normal and cortical reeler Purkinje cells through random interactions between parallel fibres and dendritic growth cones. We have defined this process with the aid of computer simulation techniques. Interactions appear to be restricted to a narrow growth front occupied by the highest centrifugally ordered terminals behind which adhesions occur at a greatly reduced frequency. The cortical reeler tree thus has fewer segments than normal because fewer parallel fibres are available, but it is surprisingly normal in most other respects. Phase III is a period of remodelling and extends from 20 dpn into adulthood when high‐ordered terminals are eroded and middle‐ordered terminals are added, with no change in total segment number in both normal and cortical reeler trees.Weaver and deeply placed reeler Purkinje cell dendritic trees are not influenced by parallel fibres. Accordingly, their growth is arrested at the end of Phase I, when both types of mutant tree have generated 100 segments by unrestrained random terminal branching. In the absence of parallel fibres, Phase II is not induced and remodelling, characteristic of Phase III, does not occur.
Frog sympathetic ganglion cells have local axon collaterals
Authors: Forehand Cynthia J. , Konopka Lukasz M. 
Published: January 2005

AbstractAmphibian autonomic ganglia have been used as simple models for studies involving the physiology of synaptic transmission. These models assume an anatomical simplicity where the ganglion is a simple relay for central nervous system output to peripheral autonomic targets. Cholinergic preganglionic fibers innervate the soma and proximal axon of the unipolar ganglion cells, which were thought to relay the information to the periphery with little ganglionic processing. However, several different types of synaptic potentials occur in response to preganglionic stimulation. Also, a variety of neuropeptides are found in both preganglionic fibers and ganglion cells; at least one of the peptides found in preganglionic fibers is known to act as a neurotransmitter in the ganglion. Finally, there may be communication between ganglion cells.In the present study, we have explored the morphology of lumbar sympathetic chain ganglion cells by intracellular injection with horseradish peroxidase to determine whether an anatomical substrate exists for processing information within these ganglia. We have shown that 39% of these cells have axons that branch within the ganglion. While both major classes of ganglion cells (B cells and C cells) had intraganglionic axon collaterals, there was a marked difference in the frequency: 65% of the C cell axons had collaterals while only 19% of the B cell axons collateralized within the ganglion. Ultrastructural examination of labeled axon collaterals indicated that these collaterals receive synaptic input; whether the collaterals also make synapses has not been definitively established.
Arborisation pattern and postsynaptic targets of physiologically identified thalamocortical afferents in striate cortex of the macaque monkey
Authors: Freund T. F. , Martin K. A. C. , Soltesz I. , Somogyi P. , Whitteridge D. 
Published: January 2005

AbstractThe monosynaptic targets of different functional types of geniculocortical axons were compared in the primary visual cortex of monkeys. Single thalamocortical axons were recorded extracellularly in the white matter by using horseradish‐peroxidase‐filled pipettes. Their receptive fields were mapped and classified as corresponding to those of parvi‐ or magnocellular neurons in the lateral geniculate nucleus. The axons were then impaled and injected intraaxonally with horseradish peroxidase. Two magnocellular (MA) and two parvicellular (PA) axons were successfully recovered and reconstructed in three dimensions. The two MA axons arborised mainly in layer 4Cβ, as did the two PA axons in layer 4Cβ. Few collaterals formed varicosities in layer 6. Both MA axons had two large, elongated clumps of bouton (approx. 300–500 × 600–1,200 μm each) and a small clump. One PA axon had two clumps (each with a core appr. 200 μm in diameter); the other had only one (appr. 150–200 μm in diameter). The PA axon with two clumps had 1,520 boutons; the other PA axon had 1,380; one MA axon had 3,200 boutons; and those of the more extensive MA axon were not counted. The distribution of postsynaptic targets as well as the number of synapses per bouton has been established for a sample of 150 PA boutons and 173 MA boutons from serial ultrathin sections. The MA axons made on average 2.1 synapses per bouton compared to 1.79 for one PA axon and 2.6 for the other. The sample of boutons taken from the two physiological types of axons contacted similar proportions of dendritic spines (52–68%), shafts (33–47%), and somata (0–3%). The postsynaptic elements were further characterized by immunostaining for GABA. All postsynaptic perikarya and some of the dendrites (4.5–9.5% of all targets) were positive for the amino acid. Near the thalamic synapse GABA‐negative dendritic shafts frequently contained lamellar bodies, an organelle identical in structure to spine apparatus. Dendritic shafts and spines postsynaptic to the thalamocortical boutons frequently received an adjacent synapse from GABA‐immunoreactive boutons.The similarity between the magno‐ and parvicellular axons in their targeting of postsynaptic elements, including the GABAergic neurons, suggests that the structural basis of the physiological differences between 4Cα and 4Cβ neurons should be sought in other aspects of the circuitry of layer 4C, such as local cortical circuits, or in the far greater horizontal extent of the thalamocortical and GABAergic axons in layer 4Cα compared to those in the β subdivision.
Intracellularly labeled stapedius‐motoneuron cell bodies in the cat are spatially organized according to their physiologic responses
Authors: Vacher Sylvette R. , Guinan John J. , Kobler James B. 
Published: January 2005

AbstractThis study examines whether the locations of stapedius‐motoneuron cell bodies are correlated with their responses to sound. Single‐unit recordings and injections of horseradish peroxidase were made in axons of stapedius motoneurons in the fascicles which run from the facial nerve to the stapedius muscle in the cat. Single units were characterized physiologically by their responses to ipsilateral, contralateral, and binaural sounds. Labeled cell bodies (N = 28) were found in all of the brainstem regions previously identified as containing stapedius motoneurons. Motoneurons characterized as having similar response properties had cell bodies in relatively circumscribed locations. Most (eight of 12) motoneurons excited by sound in either ear had cell bodies in a narrow band around the facial nucleus. Most (seven of eight) motoneurons excited by ipsilateral but not contralateral sound had cell bodies in the cleft between the superior olivary complex and the facial nucleus. All four motoneurons excited by contralateral but not ipsilateral sound had cell bodies located ventromedial to the facial nucleus. The three motoneurons excited only by binaural sound had cell bodies located dorsal to the superior olivary complex. (Two of these were also in the cleft between the superior olivary complex and the facial nucleus.) The cell body of the one motoneuron showing activity in the absence of sound stimulation was located dorsolateral to the facial nucleus. These results show that the cell bodies of stapedius motoneurons with similar electrophysiologic properties tend to have similar locations in the brainstem. The results are consistent with the idea that the stapediusmotoneuron pool is divided into subgroups that are spatially segregated in terms of their patterns of input from the two ears.
Afferent connections of the valvula cerebelli in two teleosts, the common goldfish and the green sunfish
Authors: Wullimann Mario F. , Glenn Northcutt R. 
Published: January 2005

AbstractThe afferent connections of the valvula cerebelli were examined in one cypriniform teleost (Carassius auratus) and one perciform teleost (Lepomis cyanellus) with the use of horseradish peroxidase as a retrograde tracer. Both species have ipsilateral input to the valvula from the central pretectal and dorsal accessory optic nuclei, the dorsal and ventral tegmental nuclei, the lateral nucleus of the valvula, the perilemniscal nucleus, and nucleus isthmi and contralateral input from the inferior olivary nucleus. In addition, Carassius has ipsilateral valvulopetal projections from the eminentia granularis, the praeeminential nucleus, and the isthmic primary sensory trigeminal nucleus, whereas Lepomis has bilateral (stronger ipsilaterally) valvulopetal projections from the nucleus of the locus coeruleus and the rostral corpus cerebelli.The topographical order of the cerebellopetal projections of the lateral nucleus of the valvula and inferior olive is also described, as are differential inputs to various subdivisions of the cerebellum in the two species.Information on valvulopetal projections in teleosts has thus far been limited to electroreceptive mormyrids. The present study shows that many valvular inputs related to electroreception in mormyrids have no homologue in Carassius and Lepomis.Finally, the present study indicates that the rostral part of the corpus cerebelli, but not the valvula cerebelli, in teleosts is the homologue of the anterior lobe of the corpus cerebelli in cartilaginous fishes. Thus, the valvula cerebelli is a shared derived feature (synapomorphy) of all ray‐finned fishes.
Immunocytochemical reactivity of Xenopus laevis retinal rods and cones with several monoclonal antibodies to visual pigments
Authors: Röhlich Pál , Szél ÁGoston , Papermaster David S. 
Published: January 2005

AbstractImmunocytochemical reactions with several antibodies to visual pigments were used to study visual cells of the Xenopus laevis retina. Monoclonal antibodies to bovine opsin „E,”︁ 1D4, and 4B4 (reactive with the N‐ and C‐terminus and with the loop connecting transmembrane segments 5–6, respectively) and to chicken visual pigments COS‐1 and OS‐2 (binding to mammalian red/green and blue cones, respectively), as well as a rabbit antifrog opsin serum 11–7, were applied to semithin and thin sections of the retina. The bound antibodies were detected with the peroxidase technique at the light microscopic level; a three‐stage immunogold procedure was used for electron microscopic immunocytochemistry.The overwhelming majority of rods were labeled by monoclonal antibodies „E,”︁ 4B4, 1D4, OS‐2, and serum 11–7. A small fraction (2–3%) of rods did not bind monoclonal antibodies „E”︁ and 4B4, but this minor population of rods was strongly reactive with 1D4 and to a lesser extent with OS‐2, indicating the presence of different visual pigment. These rods differ in shape from the major rod type; they are thinner, shorter, and may be comparable to the blue‐sensitive („green”︁) rods of other amphibia. Cones were morphologically heterogeneous: double cones, large single cones, and small single cones were found, and the large single and the double cones were occasionally duplicated. Double cones and large single cones (as well as their duplicated varieties) strongly bound monoclonal antibodies COS‐1 and were unlabeled by all other monoclonal antibodies, except OS‐2. The small single cone was remarkably unreactive with COS‐1 and „E,”︁ weakly labeled by 1D4 and 4B4, and most reactive with OS‐2 and 11–7. This unique pattern of immunocytochemical reactions in the small cone type indicates the uniqueness of its visual pigment from other cone types in the Xenopus retina. The present study shows the existence of two different opsins in morphologically distinct (thick and thin) rod types and at least two cone pigments in the heterogeneous cone population.
Connections and frequency representation in the auditory brainstem of the mustache bat, Pteronotus parnellii
Authors: Zook John M. , Leake Patricia A. 
Published: January 2005

AbstractThe goals of this study were to describe the cochlear frequency map of the mustache bat, Pteronotus parnellii, and to relate the organization of cochlear primary afferents to that of the second‐order projections from the cochlear nucleus to the superior olivary complex. Small deposits of horseradish peroxidase (HRP) were placed in the cochlear nucleus at sites that were physiologically characterized with respect to unit‐best frequency. From the deposits, labeled fibers were traced in the retrograde direction to the cochlea and in the anterograde direction to the superior olive.Cochleas from both experimental and control animals were examined with light and electron microscopy. The peripheral axons of spiral ganglion neurons were counted in order to quantify the unusual variation in the innervation density along the cochlear spiral of the mustache bat. Regions of increased innervation density were found at the beginning and end of the basal turn of the cochlea. The highest cochlear innervation density consistently occurred in the upper basal turn. In horseradish peroxidase tracing experiments, this region contained labeled fibers only when HRP deposits were made at sites within the cochlear nucleus with unit‐best frequencies around 60 kHz. These findings support the suggestion (Kössl and Vater, '85) that the cochlear sites of increased innervation density are related to the neural and behavioral emphasis that this echolocating bat places upon the analysis of the 60 kHz frequency band.The general arrangement of tonotopic maps within the cochlea, cochlear nucleus, and superior olive was consistent with previous observations in this bat and other mammalian species. At all three levels, there was evidence of a disproportionately large representation of frequencies around 60 kHz, similar to the enlarged representation reported within the inferior colliculus and auditory cortex of the mustache bat. In all cases there was a consistent relation between the size of the HRP deposit and the number and distribution of retrogradely labeled neurons in the cochlea. For most cases there was a similar relation between the size of the deposit and the terminal arborization field of anterogradely labeled fibers in the superior olive. However, in cases with deposits associated with the 60 kHz frequency band, the size of the labeled arborization field was more than twice as large as expected from the size of the deposits and from the extent of labeling in the cochlea. These cases suggest that the representation of frequencies around 60 kHz, already overrepresented in both the cochlea and cochlear nucleus, may be further expanded at the level of the superior olivary complex.
Intrinsic circuitry: Synapses involving the local axon collaterals of corticocortical projection neurons in the mouse primary somatosensory cortex
Authors: Elhanany Edith , White Edward L. 
Published: January 2005

AbstractPyramidal neurons in the mouse SmI cortex were labeled by the retrograde transport of horseradish peroxidase (HRP) injected into the ipsilateral MsI cortex. Terminals of the local axon collaterals of these neurons (CC terminals) were identified in SmI, and their distribution and synaptic connectivity were examined. To avoid confusion, terminals in SmI cortex labeled by the anterograde transport of HRP injected into MsI were eliminated by lesioninduced degeneration. Lesions of MsI were made 24 hours after the injection of HRP; postlesion survival time was 4 days.Most CC axon terminals occurred in layers III and V where they formed asymmetrical synapses. Of 139 CC synapses in layer III and 104 in layer V, approximately 13% were formed with dendritic shafts. Reconstruction of 19 of these dendrites from serial thin sections showed them to originate from both spiny and nonspiny neurons. Most synapses of CC terminals (about 87%) were onto dendritic spines. In contrast, White and Keller (1987) demonstrated that terminals belonging to the local axon collaterals of corticothalamic (CT) projection cells synapse mainly with dendritic shafts of nonspiny neurons: 92% onto shafts, the remainder onto spines. The distribution of asymmetical synapses onto spines and dendritic shafts was analyzed for neuropil in layers III, IV, and V. Depending on the layer, from 34 to 46% of the asymmetrical synapses in the neuropil were onto dendritic shafts. Results showing that CC and CT terminals form proportions of axodendritic vs. axospinous synapses that differ from each other, and from the neuropil indicate that local axon collaterals are highly selective with regard to their postsynaptic elements.
Postnatal development of preproenkephalin mRNA containing neurons in the rat lower brainstem
Authors: Morita Yasuhiro , Zhang Jian‐Hua , Hironaka Takashi , Tateno Emiko , Noguchi Koichi , Sato Makoto , Kiyama Hiroshi , Tohyama Masaya 
Published: January 2005

AbstractPostnatal developmental changes of preproenkephalin (PPE) gene expression in rat brainstem neurons were studied by in situ hybridization histochemistry. On the basis of PPE mRNA expression, brainstem neurons were categorized into three types: 1 type I neurons were characterized by constant or increasing expression of PPE mRNA during postnatal development; 2 type II neurons started to express PPE mRNA several days after birth and continued to do so thereafter; and (3) type III neurons showed transient expression of PPE mRNA or stopped expressing the mRNA during early postnatal development.Type I PPE neurons were observed in diverse brainstem structures including the mesencephalic and pontine central gray matter, various reticular and raphe nuclei, the ventral tegmental area of Tsai, the interpeduncular nucleus, the nucleus of the brachium of the inferior colliculus, the ventral and dorsal tegmental nuclei of Gudden, the sphenoid nucleus, the laterodorsal tegmental nucleus, Barringtons nucleus, the parabrachial region, the lateral lemniscus and its related nuclei, the trapezoid nucleus, the rostral and ventromedial periolivary nuclei, the mesencephalic trigeminal and principal sensory trigeminal nuclei, the locus coeruleus, the subcoeruleus nucleus, the medial and spinal vestibular nuclei, the dorsal and ventral cochlear nuclei, the medial and lateral cerebellar nuclei, the Roller nucleus, and the intermedius nucleus of the medulla. Type II PPE neurons were found in the superior colliculus, the inferior colliculus, the central part of the dorsal tegmental nucleus, and as Golgi neurons in the granular layer of the cerebellum. Type III PPE neurons were located in the substantia nigra, the red nucleus, the superior olive, the motor trigeminal nucleus, the facial nucleus, the inferior olive, the dorsal motor nucleus of the vagus, and the hypoglossal nucleus.Such region‐specific expression of the PPE gene during postnatal ontogeny suggests that rat brainstem PPE neurons may be involved in a variety of developmental events, such as cell proliferation, differentiation, and migration.
Developmental changes in the distribution of retinal catecholaminergic neurones in hamsters and gerbils
Authors: Mitrofanis John , Finlay Barbara L. 
Published: January 2005

AbstractAlthough Syrian hamsters and Mongolian gerbils are closely related, they have quite different patterns of retinal ganglion cell distribution and different patterns of retinal growth that produce their distributions. We have examined the morphology and distribution of catecholaminergic (CA) neurones in adult and developing retinae of these species in order to gain a more general understanding of the mechanisms producing cellular topographies in the retina. CA neurones were identified with an antibody to tyrosine hydroxylase (TH), the rate limiting enzyme in the production of catecholamines.In adult retinae of both hamsters and gerbils, most CA somata were located in the inner part of the inner nuclear layer (INL) and CA dendrites spread in a outer stratum of the inner plexiform layer (IPL). Their somata varied with retinal position, being largest in temporal and smallest in central retina. In hamsters, but not gerbils, a small number of CA interplexiform cells was also observed. In development, CA somata of hamster retinae were observed first in the middle and /or scleral regions of the cytoblast layer (CBL) at P (postnatal day) 8. By P12, CA somata were commonly located in the inner part of the INL and their dendrites spread into the outer region of the IPL. In developing gerbil retinae, CA somata were first observed at P6 in the middle of the CBL. Over subsequent days, they migrated into the inner part of the INL and spread their dendrites into the outer strata of the IPL.In both hamsters and gerbils, CA cells were initially concentrated in the superior temporal margin of the retina. In hamsters, this supero‐temporal concentration persisted until adulthood, whereas in adult gerbils, the greatest density of CA cells was found just superior to the visual streak. These distributions were distinct from those of the ganglion cells in adult and developing retinae of each species. We discuss the role of maturational expression of TH, cell death, and retinal growth in the generation of the distinct distribution of the CA cells.
Vomeronasal and olfactory nerves of adult and larval bullfrogs: II. Axon terminations and synaptic contacts in the accessory olfactory bulb
Authors: Burton Paul R. 
Published: January 2005

AbstractThe ultrastructure of the accessory olfactory bulb (AOB) of the bullfrog tadpole and adult was examined, and the main difference between tadpole and adult is that the latter is more compact and shows more synapses. Except for vomeronasal (VMN) glomeruli, the AOB is not highly organized, with mitral cell neurons scattered throughout the neuropil. VMN axon terminals from asymmetric synapses with mitral cell dendrites in glomeruli; in VMN axon terminals, dense‐cored vesicles are seen along with the more abundant lucent vesicles 40–50 nm in diameter. Counts indicated that more than 90% of the dendro‐dendritic synapses between mitral cells and presumed granule cells are of the asymmetrical type, and reciprocal asymmetrical‐symmetrical synapses are not common. Lucent vesicles with round or slightly ellipsoidal profiles and less abundant dense‐cored vesicles 60–90 nm in diameter are found in pre‐ and postsynaptic dendrites; sometimes the dense‐cored vesicles lie against or near the presynaptic membrane. Microtubules were often seen to be closely associated with pre‐ and postsynaptic elements of dendro‐dendritic synapses. The most characteristic feature of mitral cell bodies, apart from their large size, is an extensive Golgi system that may extend well into their major dendritic extensions. Dense‐cored vesicles are associated with Golgi membranes, from which they probably originate. Centrioles are associated with the Golgi system, and some become basal bodies and give rise to cilia in some mitral cells.