bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopic studies of serially sectioned cat spinal α‐motoneurons. III. Motoneurons innervating fast‐twitch (type fr) units of the gastrocnemius muscle
Authors: Kellerth J‐O. , Berthold C‐H. , Conradi S. 
Published: January 2005

AbstractTwo intracellularly stained cat gastrocnemius α‐motoneurons of the FR‐type (Burke et al., '73) were studied ultrastructurally. The architecture and synaptology of the cell body and proximal parts of the dendrites were analyzed from a long series of consecutive sections, according to a method presented in a preceding paper (Conradi et al., '79a). Several of the dendrites had a base diameter exceeding 10 μm. The proportion of the surface covered by boutons was 40‐50% for the cell body and about 80% for the proximal dendrites. In both regions, about 20% of the boutons were of the S‐type and 70% of the F‐type. The large C‐boutons were clustered around the dendritic roots and were also present on the axon hillock. M‐boutons of dorsal root origin were located on the proximal parts of the majority of the dendrites.
The development of descending and dorsal root connections in the lumbosacral spinal cord of the postnatal rat
Authors: Gilbert Mark , Stelzner Dennis J. 
Published: January 2005

AbstractLight and electron microscopy were used to study degenerating axons and synaptic endings in the lumbosacral spinal cord at different stages of postnatal development in the rat. After dorsal root section (L5‐S1) or mid‐thoracic hemisection of the spinal cord (T6‐T8), the distribution and type of degeneration argyrophilia were studied with the light microscope over varied post‐operative survival periods using a modified Fink‐Heimer method (Leonard, '74). The light microscopic results were correlated with the appearance of electron dense degeneration seen using the electron microscope.The distribution of degeneration found in the lumbosacral spinal cord after dorsal root section was similar at the neonatal (4d), weanling (21d) and adult stages. At the neonatal stage, the type of degeneration argyrophilia appeared at an earlier postoperative survival period (12 hours), and was maximal at an earlier time (12‐18 hours) than in older animals. The appearance of electron dense degeneration using the electron microscope matched the light microscopic findings. Electron dense degenerating synaptic knobs were found at the neonatal stage making asymmetrical contact with small dendrites in areas of the dorsal horn showing degeneration argyrophilia.No degeneration was found in the dorsal funiculus, dorsal horn or intermediate nucleus of Cajal (INC) after mid‐thoracic hemisection at the neonatal stage although degeneration was present elsewhere in the intermediate gray, in the ventral gray, and in the ventral and lateral funiculi. At this stage, the type of degeneration argyrophilia and time course of degeneration in the gray and white matter was identical to that found after dorsal root section in neonatal animals. The distribution of degeneration was not mature in the lumbosacral enlargement until 15d of age and the degeneration was still immature in the dorsal horn and INC at 21d of age.Although degeneration argyrophilia and electron dense degeneration was found in the ventromedial gray (lamina VIII) and lateral gray (laminae VI‐VII) at the neonatal stage, electron dense degenerating synaptic knobs were not observed in these areas until 12d of age for the ventromedial and 18d of age for the lateral gray matter even using a large number of different survival periods.Degenerating synaptic endings were first observed after mid‐thoracic hemisection during the period when behavioral maturation is nearing completion in the hindlimbs, and when response depression (spinal shock) increases and response recovery decreases after mid‐thoracic spinal transection (Weber and Stelzner, '77). Our data suggest that either the number of connections from descending sources increases markedly in the gray matter of the lumbosacral spinal cord during this period or connections, already present, reach a state of maturity where they can first be observed using the degeneration method of analysis.
Sympathetic neurons in the cat spinal cord projecting to the stellate ganglion
Authors: Chung Kyungsoon , Chung Jin Mo , Lavelle F. W. , Wurster R. D. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was injected into the stellate ganglia of anesthetized cats. After a 2‐day survival time the spinal cord was processed for the HRP reaction to study the distribution of the preganglionic neurons which project to the stellate ganglia. HRP‐labeled neurons in the cord were located exclusively on the side ipsilateral to the injected stellate ganglia and were concentrated in four distinct areas: (1) intermediolateral cell column (78.2%), (2) lateral funiculus (18.5%), (3) intercalated area and (4) central autonomic area (3.3% for the latter 2 areas). Their distribution pattern in the very rostral pole of the thoracic sympathetic preganglionic cell column was different from the typical thoracic pattern in that a greater proportion of the cells were located in the lateral funiculus, and a few labeled cells were observed in the ventral horn. Longitudinally, a wide range (C8‐T8) of spinal cord levels projected to the stellate ganglia, with a peak at the T2 level. These observations infer that a large population of axonal processes of sympathetic preganglionic neurons traveled several segments of the spinal cord through an intraspinal pathway before exiting a particular ventral root.
Some telencephalic connections in the frog, Rana pipiens
Authors: Kicliter Earl 
Published: January 2005

AbstractSome afferent, efferent and intrinsic connections of the telencephalon of Rana pipiens were studied using a horseradish peroxidase method. Afferents to the telencephalon from thalamic and brain stem cell groups were demonstrated. These findings, taken together with the results of previous studies, indicate that separate thalamic cell groups project visual, auditory and somatosensory information onto the striatum. A separate thalamic cell group projects to the medial telencephalic wall and probably conveys visual and somatosensory information. These telencephalic afferent systems do not appear to be directly comparable to those of birds and reptiles. Additionally, some telencephalic efferents demonstrated in previous studies using anterograde degeneration techniques were confirmed, and some intratelencephalic connections were identified.
Facial thermal input to the trigeminal spinal nucleus of rabbits and rats
Authors: Dickenson A. H. , Hellon R. F. , Taylor D. C. M. 
Published: January 2005

AbstractIn rabbits and rats under urethane anesthesia, a systematic survey was made of the caudal trigeminal nucleus, using glass coated tungsten microelectrodes. This revealed many neurons in the marginal layer sensitive either to warming or cooling the facial skin. The majority of these neurons were specifically temperature sensitive.In rats, a somatotopic arrangement of cold receptive fields was evident with in the marginal layer of the trigeminal nucleus, with the ophthalmic division of the trigeminal nerve represented most laterally, the mandibular most medially and the maxillary division represented over most of the recording region. This arrangement is similar to the mediolateral distribution seen in cats. In rabbits, the distribution was less rigorous but the ophthalmic division tended to be represented caudally and the mandibular division rostrally. The maxillary division was represented over most of the recording region. All receptive fields were ipsilateral and showed spatial convergence of input. Both rabbits and rats possessed a concentration of thermal receptive‐fields around the nose, whisker pad and mouth.At steady skin temperatures, marginal units gave bell‐shaped intensity functions which were very similar to those reported for the cold and warm receptors. With rapid changes of temperature, neurons responded with a dynamic outburst which corresponded to the equivalent receptor response.
The lateral cervical nucleus in the cat: Anatomic organization of cervicothalamic neurons
Authors: Craig A. D. , Burton H. 
Published: January 2005

AbstractThe morphology of the lateral cervical nucleus (LCN) and the organization of the cervicothalamic projection neurons were studied in cats which had received thalamic injections of horseradish peroxidase (HRP). The boundaries of the LCN were defined following very large thalamic HRP injections. Roughly 92–97% of LCN cells project contralaterally to thalamus; an additional 1‐5% project ipsilaterally. Computer‐assisted measurements of perikaryal areas demonstrated that there are two sizes of LCN cells, large (175–900 μm2) and small (< 175 μm2); the small cells are localized in the medial third of the LCN. LCN cells which are not labeled after large thalamic HRP injections are predominantly small, medially‐located neurons.Small HRP injections into physiologically identified regions of ventroposterior thalamus demonstrated that cervicothalamic neurons are organized in a topography consistent with that observed physiologically in the LCN (Craig and Tapper, '78). Dorsolateral LCN cells are retrogradely labeled from nucleus ventroposterolateralis, pars lateralis (VPL1), ventromedial LCN cells are labeled from pars medialis (VPLm), and a few medial cells are labeled from nucleus ventroposteromedialis (VPM). A few cells in the medial portion of the LCN are also labeled from each part of ventroposterior thalamus. Some interspersion was observed even in the cases with the most well‐restricted labeling. We conclude that the LCN maintains a basic somatotopographic organization with an inherent variability, certain aspects of which are consistently demonstrable both physiologically and anatomically. Evidence was also obtained suggestive of a rostrocaudal inversion in the cervicothalamic projection. The cervicothalamic projection, the differentiation of the medial LCN subpopulation, and the possible redefinition of the LCN are discussed in light of these results.
Localization of neurons in the rat superior cervical ganglion that project into different postganglionic trunks
Authors: Bowers C. W. , Zigmond R. E. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was used to determine whether neurons in the rat superior cervical ganglion (SCG) are localized in regions of the ganglion as a function of the postganglionic trunk they utilize. In separate experiments, each of the two major postganglionic trunks was cut 1–3 mm from the SCG and solid HRP was applied to the cut end proximal to the ganglion. The results demonstrated that the cell bodies of neurons whose axons project out the internal carotid nerve (ICN) were located primarily in the rostral part of the ganglion. Cell bodies of neurons whose axons project out the external carotid nerve (ECN) were located primarily in the caudal part. The total percentages of neurons with axons in the ICN and ECN were about 35% and 45% respectively. When HRP was applied to both these trunks, 73% of the neurons in the SCG were labeled. In the caudal portion of the ganglion, an additional group of neurons was observed whose axons project into the cervical sympathetic trunk. Control studies indicated that the neuronal labeling observed in our experiments was due to retrograde axonal transport rather than the direct uptake of HRP by neuronal cell bodies. Thus, neuronal subpopulations exist in specific regions of the rat SCG. The significance of these results to biochemical and electrophysiological studies is discussed.
The distribution of retino‐collicular axon terminals in rhesus monkey
Authors: Pollack J. G. , Hickey T. L. 
Published: January 2005

AbstractThe retino‐collicular projections in rhesus monkeys were studied using standard autoradiographic and degeneration techniques. A computer based technique was developed which provided a flattened visual display of the retinal projection onto the entire superior colliculus, quantified the area covered by such projections for different segments of the colliculus and showed how this morphological pattern varied with depth beneath the collicular surface.In the anterolateral third of the colliculus (i.e., the foveal representation) the retinal projection was light, confined to a narrow region of the superficial gray and contributed primarily by the contralateral eye. In the remaining binocular segment of the superior colliculus the retinal projections showed a marked degree of local patterning, that in many instances appeared as bands of label. By combining eye removal and eye injection procedures in a single animal and comparing adjacent sections processed for autoradiography and stained for degeneration, it was possible to assess the amount of overlap between retino‐collicular projections from the two eyes. These experiments showed that total segregation of retinal afferents does occur in the monkey superior colliculus, but what occurs more often is a situation where the density of inputs from the two eyes varies reciprocally as one moves across the part of the colliculus that represents the binocular visual field.
Pikeperch horizontal cells identified by intracellular staining
Authors: Hassin Guido 
Published: January 2005

AbstractMicropipettes filled with Procion yellow dye were used to record from and to stain pikeperch horizontal cells intracellularly. Three major types were found: a distal layer (H1) of relatively small cells which were luminosity or L‐type; a second and more proximal layer of larger L‐type cells (H2); and a third and yet more proximal layer of very stellate chromatic or C‐type cells (H3). A few anucleate processes which displayed slow‐potentials were found in the proximal area of the inner nuclear layer. Cells of each of the three layers were shown to be cone related by both anatomical and physiological methods.L‐type cells were further categorized by the area over which each exhibited spatial summation and the relative sensitivity of each to red and green lights. Receptive field sizes of H2's were found to range from less than 2 mm to greater than 5 mm in diameter, whereas those of the few H1's tested were all less than 2 mm. Results from spectral screening tests indicate that most H1 and H2 cells are maximally sensitve to orange light, whereas the H3 cells hyperpolarize maximally to green and depolarize maximally to red. A small percentage of sampled C‐cells displayed an additional depolarization to violet.
Synaptic connections linking cones and horizontal cells in the retina of the pikeperch (Stizostedion vitreum)
Authors: Witkovsky Paul , Burkhardt Dwight A. , Nagy Andre R. 
Published: January 2005

AbstractCones and horizontal cells of the pikeperch retina were studied with morphological and physiological techniques. Gap junctions were observed between cone pedicles and basal processes emitted by neighboring cones. Intracellular recordings showed that the light‐evoked hyperpolarizing cone response was enhanced by light falling upon neighboring receptors within a radius of 50μm. We suggest that the network of gap junctions between cones mediates the summative lateral interaction described.Three sub‐classes of horizontal cells (H1, H2, H3) send dendrites to cones; H1 and H2 cells appear to appear to contact twin cones, exclusively or preferntially, whereas H3 cells appear to synapse only with single cones. Horizontal cells of the same sub‐class are joined by gap junctions between dendrites or at the lateral faces of perikarya. These unions extend over several μm2 and as seen in transmission electron microscopy consist of patches of close apposition alternating with areas of membrane separation, folding and occasional zonulae adherentes. Freeze‐fracture profiles of horizontal gap junctions show localized areas of dense particle aggregation on the P‐face and pits on the E‐face flanked by regions of unspecialized membrane. These morphological findings provide support for the known spatial and color‐coding properties of pikeperch horizontal cells.
A Golgi study of the ventral tegmental area of Tsai and interfascicular nucleus in the rat
Authors: Phillipson O. T. 
Published: January 2005

AbstractThe ventral tegmental area of Tsai (VTA) and interfascicular nucleus of the adult rat brain has been studied with two variants of the Golgi method in three planes of section. Neurons were studied in relation to the cytoarchitectural groupings of the VTA. Dendritic organisation and dendritic fields were mapped out for each cytoarchitectural subgroup and cell types within each subgroup were classified on the basis of cell size and dendritic morphology.In each subnucleus of VTA, neurons had distinct characteristics. In nucleus paranigralis neurons were small to medium in size and their dendritic fields organised in an approximately horizontal plane orientated in an anteromedial direction and slanting dorsally over the interpeduncular nucleus and fossa. Neurons of the parabrachial group were small to medium sized with no preferential orientation. In nucleus linearis raphe caudalis small neurons were strongly orientated in the plane of the nucleus in a dorso‐ventral direction slanting forwards. Neurons in the interfascicular group were small to very small and their maximum dendritic extents were seen in the horizontal plane. In frontal section they formed a compact ball of cells in the midline and were separated on either side from the larger neurons in the medial edge of nucleus paranigralis.Ingeneral VTA neurons tended to fall into one of two morphological categories. Type 1 were small to medium, and had two to four primary dendrites which divided into varicose secondary dendrites. Type 2 were medium sized, with two to five primary dendrites. Both primary and secondary dendrites and the cell soma of Type 2 neurons were moderately spiny. Secondary dendrites were not varicose. Forms also occurred which were intermediate between Types 1 and 2. In the nucleus paranigralis, Type 1 was more common medially, while Type 2 was more common laterally, particularly in the ventrolateral paranigral region. Only neurons of Type 1 were seen in nucleus linearis raphe and interfascicular nuclei. Local axon circuits were observed to arise from the primary dendrites of Type 1 neurons and to ramify close to neighbouring neurons. Axon swellings from such circuits were observed to make apparent contact with primary dendrites of nearby neurons and clusters of axon swellings were observed near cell somas of neighbouring impregnated neurons of similar type.The results are discussed and particular attention is paid to the similarities and differences between VTA and the substantia nigra pars compacts (SNC). The major difference appears to be that, whereas in SNC dendrites are organised in vertical as well as horizontal planes, in the VTA no long ventrally directed dendrites were observed. Combining these results with the known cytoarchitecture and connections of VTA and SNC, it appears that fundamental differences occur between VTA and some neurons of the SNC, both in the nature of their morphology and intrinsic organisation, and in the organisation of their efferent and afferent connections.
Endocytic activity of subependymal microglial cells in the toad brain: A cytochemical study of peroxidase uptake
Authors: McKenna Olivia C. 
Published: January 2005

AbstractA population of microglial cells that rapidly incorporate extracellular material introduced into the ventricular system has been identified just beneath the ependyma of all four cerebral ventricles in the toad (Bufomarinus). In untreated tissue these cells appear to be scatterd, possess few processes and have and elongate shape with their long axes lying parallel to the ventricular surface. Their most distinctive ultrastructural features are nucleicontaining clumps of chromatin, cytoplasmic dense bodies and single strands of granular endoplasmic reticulum. When horseradish peroxidase (HRP) is perfused through the ventricular system and the tissue processed using the DAB cytochemical method, the cells change shape and incorporate HRP into cytoplasmic structures. Even after very short perfusion periods (2–5 minutes) cells become rounded, the surface is ruffled and pseudopodia develop that contain characteristic flocculent material. Reaction pruduct for HRP is contained in plain and coated vesicles, tubules, vacuoles and long structures composed of two closely apposed menranes. At these early times, relatively few multivesicular bodies and dense bodies contain reaction product, but when the cells are viewed at longer time periods after the ventricular perfusion of HRP an increasing proportion of the multivesicular bodies and dense bodies contain reaction product. By 320 minutes reaction product is found almost exclusively in these two organelles. In addition, many pseudopodia containing dense bodies with peroxidase activity are found in the neuropil; some, but not all, can be traced from the subependymal microglial cells. The cell bodies have resumed their flattened shape, When compared to the subependymal microglial cells, other brain cells‐oligodendrocytes, astrocytes, ependymal cells and neurons‐contain relatively little reaction product at short time intervals; only by 320 minutes are moderate amounts of HRP present. Because of the position of the microglial cells and their ingestive capacity, it is suggested that they function to protect the brain from foreign substances entering form the CSF.
Development of synaptic arrays in the inner plexiform layer of neonatal mouse retina
Authors: Fisher Leslie J. 
Published: January 2005

AbstractRetinas from mice of the C57BL/6 strain were sampled at frequent intervals from birth to postnatal day 33 to determine the numerical density of conventional and ribbon synapses within the inner plexiform layer (IPL) as a function of time. Synaptic arrays of the IPL were formed in three phases. During Phase I, from day 3 to day 10, conventional synapses were produced at a mean rate of 0.44 synapses/1,000 μm3/hour, but no ribbons were seen. During Phase II, from day 11 to day 15, ribbons formed at a rate of 0.38 ribbons/1,000 μm3/hour and conventional synapses were produced at a rate of 1.15 synapses/1,000 μm3/hour. Phase III began at day 15, the approximate time of eye opening in these animals, and was characterized by a sharp reduction in the rate of production of both ribbons and conventional synapses. During this phase ribbons achieved a final mean density of 113 ribbons/1,000 μm3 and conventionals achieved a final mean density of 250 synapses/1,000 μm3. Serial synapses appeared in Phase II but remained at low densities.