bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topographical and ultrastructural investigation of the habenulo‐interpeduncular pathway in the rat: A wheat germ agglutinin‐horseradish peroxidase anterograde study
Authors: Kawaja M. D. , Flumerfelt B. A. , Hrycyshyn A. W. 
Published: January 2005

AbstractThe topographical and ultrastructural organization of the habenular projection to the interpeduncular nucleus (IPN) of the rat was examined employing the anterogradely transported tracer wheat germ agglutininhorseradish peroxidase (WGA‐HRP) and the chromogen tetramethylbenzidine (TMB). Unilateral placements of WGA‐HRP in the habenular complex resulted in heavy terminal labelling in the rostral, central, and intermediate subnuclei bilaterally, and in the lateral subnuclei ipsilaterally. The apical subnucleus possessed only a sparse amount of label. Placements confined to the medial habenula (mH) produced similar results to those observed when the entire habenula was filled, suggesting that the afferent contribution made by the lateral habenula (lH) to the IPN is small.Unilateral placements of WGA‐HRP in the dorsal portion of the mH resulted in heavy, predominantly ipsilateral labelling in the lateral subnucleus and the dorsal cap of the rostral subnucleus. In the lateral subnucleus labelled habenular terminals consistently contacted single dendritic processes shared by one or more other boutons, possibly of nonhabenular origin. Labelled habenular terminals in the rostral subnucleus normally contacted one or two dendrites. Labelled terminals in both subnuclei possessed clear, spherical vesicles and a variable number of dense‐core vesicles. Unilateral placements of WGA‐HRP in the ventral portion of the mH resulted in heavy labelling in the rostral half of the rostral subnucleus with a slight ipsilateral predominance, and in the central and intermediate subnuclei bilaterally. Terminal labelling was observed in crest and S synapses in the intermediate and central subnuclei respectively. Crest synapses, which consist of two parallel habenular terminals contacting an attenuated dendritic process, normally possessed label in only one of the two boutons. In the central subnucleus labelled horizontal axons formed several en passant S synapses with dendritic processes of small and medium diameter. These synaptic specializations of habenular axons contained numerous clear, spherical vesicles.This study demonstrates that a major topographically organized projection to the IPN originates from two distinct subpopulations of habenular neurons which comprise a dorsal sector and a ventral sector of the mH. Ultrastructural examination demonstrated that axons originating from neurons in the ventral and dorsal mH form characteristic contacts in the various IPN subnuclei.
Sympathetic and afferent somata projecting in hindlimb nerves and the anatomical organization of the lumbar sympathetic nervous system of the rat
Authors: Baron Ralf , Jänig Wilfrid , Kollmann Wolfgang 
Published: January 2005

AbstractThe anatomy of the sympathetic pathways from the spinal cord to the lumbar sympathetic trunk and the inferior mesenteric ganglion was studied systematically in the rat. Details of the arrangements of white and gray rami communicantes, sympathetic trunk ganglia, the intermesenteric nerve, and the lumbar splanchnic nerves are summarized. A modified nomenclature for the segmental ganglia of the paravertebral sympathetic chain is proposed.Cell bodies of sensory and sympathetic axons projecting to the skin and skeletal muscle of the rat hindlimb were labeled retrogradely with horseradish peroxidase (HRP) in order to study numbers, segmental distribution, and location of the somata of these neurons quantitatively. HRP was applied to the nerves supplying skeletal muscle (gastrocnemius‐soleus, GS), hairy skin (sural, SU; saphenous, SA) and to a mixed nerve (tibial, TI). All sensory somata and 96.4% of the sympathetic cell bodies were located ipsilaterally. Sensory somata were commonly restricted to two adjacent dorsal root ganglia (usually L3‐4 for SA; L4‐5 for GS, TI; L5‐6 for SU). Although the sympathetic somata were more widely distributed rostrocaudally (four to six segments), their maximum was always located one or two segments more cranially than the sensory outflow, i.e., corresponding to the rami communicantes grisei.From the data, it is estimated that 420 sympathetic and 530 afferent neurons project into GS, 590 and 3,610 into SU, 920 and 3,750 into SA, and 1,070 and 5,760 into TI. These absolute neuron numbers are compared with electron microscopic fiber counts from the literature.
Substance P‐like immunoreactive amacrine cells in the cat retina
Authors: Pourcho Roberta G. , Goebel Dennis J. 
Published: January 2005

AbstractSubstance P‐like immunoreactivity was localized by immunocytochemical techniques to two subpopulations of amacrine cells in the cat retina. One cell was a unistratified amacrine with processes ramifying within stratum 4 of the inner plexiform layer. The other cell type was a bistratified cell with processes in both stratum 1 (s1) and stratum 4 (s4). Both cell types were seen with their somas displaced to the ganglion cell layer as well as in the conventional amacrine location in the inner nuclear layer. Substance P cells were present in the greatest density within the area centralis and decreased in number toward the periphery. The ratio of amacrine to displaced amacrine cells also decreased peripherally. However, the coverage by immunoreactive fibers in s4 remained three times that seen in s1. Computer‐assisted analysis confirmed the location of substance P‐containing processes at 5‐15% (s1) and 50‐70% (s4) depth levels in the inner plexiform layer. A comparison of substance P‐like immunoreactivity in light‐ and dark‐adapted cat retinas showed no apparent differences in the distribution of immunoreactivity due to lighting conditions.
Local circuit neurons of macaque monkey striate cortex: II. Neurons of laminae 5B and 6
Authors: Lund Jennifer S. , Hawken Michael J. , Parker Andrew J. 
Published: January 2005

AbstractThis study investigates the intrinsic organization of axons and dendrites of aspinous, local circuit neurons of the macaque monkey visual striate cortex. These investigations use Golgi Rapid preparations of cortical tissue from monkeys aged 3 weeks postnatal to adult. We have earlier (Lund, '87) described local circuit neurons found within laminae 5A and 4C; this present account is of neurons found in the infragranular laminae 5B and 6. Since the majority of such neurons are GABAergic and therefore believed to be inhibitory, their role in laminae 5B and 6, the principal sources of efferent projections to subcortical regions, is of considerable importance. We find laminae 5B and 6 to have in common at least one general class of local circuit neuron–the “basket” neuron. However, a major difference is seen in the axonal projections to the superficial layers made by these and other local circuit neurons in the two laminae; lamina 5B has local circuit neurons with principal rising axon projections to lamina 2/3A, areas whereas lamina 6 has local circuit neurons with principal rising axon projections to divisions of 4C, 4A, and 3B. These local circuit neuron axon projections mimic the different patterns of apical dendritic and recurrent axon projections of pyramidal neurons lying within laminae 5B and 6, which are linked together by both dendritic and axonal arbors of local circuit neurons in their neuropils extending between the two laminae. The border zone between 5B and 6 is a specialized region with its own variety of horizontally oriented local circuit neurons, and it also serves as a special focus for pericellular axon arrays from a particular variety of local circuit neuron lying within lamina 6. These pericellular axon “baskets” surround the somata and initial dendritic segments of the largest pyramidal neurons of layer 6, which are known to project both to cortical area MT (V5) and to the superior colliculus (Fries et al., '85). Many of the local circuit neurons of layer 5B send axon trunks into the white matter, and we therefore, suspect them of providing efferent projections. The axons of lamina 6 local circuit neurons have not been found to make such clear‐cut contributions to the white matter.
Ultrastructural features of functionally identified primary afferent neurons with C (unmyelinated) fibers of the guinea pig: Classification of dorsal root ganglion cell type with reference to sensory modality
Authors: Sugiura Yasuo , Hosoya Yasuhiko , Ito Ryuzo , Kohno Kunio 
Published: January 2005

AbstractIntracellular labeling of neurons permitted a direct correlation of neuronal profiles with sensory modality of cutaneous receptors. In the guinea pig, 47 neurons in the dorsal root ganglion (displaying C‐fiber conduction velocities) were labeled with horseradish peroxidase (HRP) by iontophoresis after determining the sensory modality. Receptive fields were explored with systematic “natural” stimuli. Cell areas of all C‐fiber units were measured by tracing the cellular contour in light microscopy. The mean cellular diamter calculated from cell areas was 21.8 μm in the second cervical ganglion of the guinea pig. Mean cell diameter for high‐threshold mechanoreceptors was 20.9 μm, 24.6 μm for polymodal nociceptors, and 25.7 μm for mechanicalcold nociceptors. Electron microscopic observations showed that all labeled neurons of C‐fiber units had profiles of small, dark type‐B neurons. Neurons representative of each sensory modality exhibited different cell features, each belonging to a distinct subtype of small B neurons. High‐threshold mechanoreceptor and mechanical‐cold nociceptor displayed a peripheral lamellar arrangement of cisternae of endoplasmic reticulum (ER), corresponding to the B1 subtype. Polymodal nociceptor units were characteristically of the B2 subtype, in which stacks of long and short cisternae of ER were distributed randomly throughout the cytoplasm, and the arrangement of Golgi bodies varied among these cells. Cooling receptors displayed poorly developed, flattened cisternae of ER and numerous vesicles, typical of the B3 subtype. These results imply that all C‐fiber cells belong to the small B‐type cell category and that the ultrastructural features of the neuron in the dorsal root ganglion may reflect the sensory modality of the receptive field.
Distribution of opioid peptides in the preoptic region: Immunohistochemical evidence for a steroid‐sensitive enkephalin sexual dimorphism
Authors: Simerly R. B. , McCall L. D. , Watson S. J. 
Published: January 2005

AbstractThe distribution of cells and fibers that contain opioid peptides within the preoptic region of the rat was examined immunohistochemically. Cells and/or fibers that contain peptides derived from each of the three major opioid peptide families were differentially stained by using antisera that recognize unique derivatives of each precursor molecule and do not crossreact with members of the other opioid peptide families. A beta‐endorphin (ßE) antiserum was used to stain fibers that contain peptides derived from the proopiomelanocortin molecule, and dynorphin‐containing cells were identified by using an antiserum directed toward dynorphin B (Dyn B) that does not show detectable cross‐reactivity with enkephalin‐related peptides. An antiserum raised against peptide E (PE), which does not appear to cross‐react significantly with dynorphin peptides, was used to localize enkephalin cells and fibers. Each family of opioid peptides showed a unique distribution in the preoptic region. ßE‐immunoreactive fibers were primarily localized to the preoptic part of the periventricular nucleus, with moderate densities of fibers contained in the anteroventral periventricular nucleus (AVPv) and medial preoptic nucleus (MPN). Dyn B‐immunoreactive fibers showed a somewhat more uniform distribution throughout the region, and only a few Dyn B‐stained cells bodies were found within the medial preoptic area. In contrast, the preoptic region contained hundreds of PE‐immunoreactive cells, which were particularly numerous within the AVPv, MPN, and anterodorsal preoptic nucleus. The AVPv and MPN also contained discretely localized plexuses of PE‐stained fibers.Although the overall distributions of opioid peptide‐containing fibers within the preoptic region were quite similar in male and female rats, differential distributions of fibers were found in certain nuclei such as the AVPv and MPN, and they were correlated with previously identified cytoarchitectonic sexual dimorphisms. Such differential distributions were particularly distinct for enkephalin‐containing fibers. Although the AVPv is larger in female rats, it contained more PE‐immunoreactive cell bodies in male rats, and we have shown here that this sexual dimorphism appears to be at least partially dependent on perinatal levels of gonadal steroids. In contrast, no difference in the number of PE‐stained cells was found within the anterodorsal preoptic nucleus of male and female animals, indicating that sexual differences are not a general characteristic of enkephalinergic cells in the preoptic region of the rat. These findings suggest that gonadal steroids act during development to organize opiate‐containing pathways within the preoptic region, which may contribute to the expression of sexually differentiated physiological and behavioral responses.
Brainstem origin of serotonin‐ and enkephalin‐immunoreactive afferents to the opossum's cerebellum
Authors: Walker James J. , Bishop Georgia A. , Ho Raymond H. , King James S. 
Published: January 2005

AbstractPrevious studies have described the distribution of serotonin‐ and enkephalin‐immunoreactive elements in the posterior lobe vermis of the oposum's cerebellum. In the present study we have used a double labeling paradigm which combines the retrograde transport of horseradish peroxidase (HRP) with serotonin and enkephalin immunohistochemistry to determine the brainstem origin of serotoninergic and enkephalinergic neurons that project to the opossum's cerebellar cortex.Subsequent to HRP injections into the posterior lobe vermis, widespread areas of the medulla and pons were found to contain retrogradely labeled neurons. Serotonin‐immunoreactive somata are present primarily in the raphe nuclei and the adjacent reticular formation. Enkephalinergic neurons were numerous in the raphe nuclei, medial accessory olive, gigantocellular reticular formation, locus coeruleus, and the nucleus of the trapezoid body. However, serotoninergic neurons that project to the cerebellum were located only in the medullary pyramids and the reticular formation adjacent to the raphe. Double‐labeled enkephalinergic neurons were located 1) within the medullary pyramids, 2) throughout the extent of the caudal medial accessory olive, 3) in the rostral subnucleus a of the medial accessory olive, 4) in the nucleus reticularis gigantocellularis pars ventralis, 5) in the nucleus reticularis lateralis, and 6) in the nucleus reticularis ventralis lateral to the inferior olivary complex.These results indicate that although neurons containing serotonin and enkephalin immunoreactivity may be present in some of the same pontine and medullary nuclei, those serotoninergic and enkephalinergic neurons that project to the cerebellum are present primarily in restricted and spatially separate regions of the caudal medulla.
Relationship between synaptogenesis and cytochrome oxidase activity in Purkinje cells of the developing rat cerebellum
Authors: Mjaatvedt A. E. , Wong‐Riley M. T. T. 
Published: January 2005

AbstractIn the adult CNS, the level of oxidative metabolism, as indicated by cytochrome oxidase cytochemistry, can be correlated with the level of neuronal activity. Specifically, heightened cytochrome oxidase activity in postsynaptic neurons can often be correlated with a greater proportion of excitatory inputs, whereas inhibitory inputs often result in a low level of cytochrome oxidase activity. This relationship has not been explored in developing neurons. To this end, cytochrome oxidase cytochemistry was used to compare the levels of oxidative metabolism in rat cerebellar Purkinje cells at various stages of their development. The results indicated that the level of cytochrome oxidase activity in Purkinje cell somata and dendrites correlated closely with the type of synaptic input (excitatory or inhibitory) received by the different segments of the cell. When the cell somata received predominantly excitatory input from climbing fibers, their mitochondria were evenly distributed between the three reactive classes: dark, moderate, and lightly reactive for cytochrome oxidase. When the cell somata received predominantly inhibitory input from basket cell terminals, lightly reactive mitochondria were the prevailing type. Further support for the correlation of excitatory synaptic input with high levels of cytochrome oxidase activity was found in the quantitation of mitochondria within Purkinje cell dendrites. These dendrites received largely excitatory input at all ages and had high levels of cytochrome oxidase activity throughout development and adulthood. There was also a relationship between the level of cytochrome oxidase activity and mitochondrial size within Purkinje cell somata and dendrites from birth to adult. Darkly reactive mitochondria had a greater mean area than moderately reactive mitochondria which, in turn, had a greater mean area than lightly reactive mitochondria. In addition, the packing density of mitochondria within the cytoplasm varied with age in both somata and dendrites. In the somata, the packing density peaked at postnatal day 7, and in dendrites, the peak occurred at postnatal day 10. These data indicate that in a developing system, postsynaptic neurons respond to sequential excitatory and inhibitory inputs by sequential heightening and lowering of their energy metabolism. Thus, cytochrome oxidase activity in a postsynaptic neuron can be correlated with the predominant type of synaptic input that it receives.
Ultrastructure of taste cells and synapses in the mudpuppy Necturus maculosus
Authors: Delay Rona J. , Roper Stephen D. 
Published: January 2005

AbstractTaste buds in the mudpuppy Necturus maculosus were examined with electron microscopy. Three cell types (dark, light, and basal) were identified and reconstructed from serial thick sections. Dark and light cells extend from the basal lamina to the surface of the tongue. The apical process of the dark cells was usually quite lamellar when viewed in cross section, in contrast to light cells, whose apical process appeared more cylindrical. Basal cells are situated at the base of the bud and do not extend processes to the surface of the tongue. The cytoplasm of basal cells contains numerous clear and dense‐cored vesicles. Small, spinelike processes (2–3 μm in length) project outward from the basal cells into the cytoplasm of the surrounding taste receptor cells. Morphologically, basal cells in mudpuppy taste buds resemble Merkel cells. Unmyelinated afferent nerve fibers enter the taste bud at the base and course through the lower portion of the bud. Synapses were found between taste receptor cells and nerve fibers, between basal cells and nerve fibers, and between basal cells and taste receptor cells. Over 65% of the synapses observed in the mudpuppy taste bud involved the basal cell. These findings suggest that basal cells play some role in chemosensory signal processing or integration of the taste response.
Time course of neocortical graft innvervation by AChE‐positive fibers
Authors: Clinton Robert J. , Ebner Ford F. 
Published: January 2005

AbstractAcetylcholinesterase (AChE)‐containing axons are the only extrinsic fibers projecting to the adult cortex that readily innervate embryonic cortical grafts up to normal densities without prior manipulation of the host brain. In the present paper we compare the time course of AChE‐positive fiber innervation in the normal mouse cortex with that seen in neocortical grafts by using AChE histochemistry as a marker for presumed cholinergic fibers. Donor tissue was taken at two different stages of gestation; before (embryonic days 12–14, or El2–14) and after (El7–19) the cortical plate is formed. Three features are analyzed: (1) the distribution and density of AChE‐containing fibers, (2) the presence of AChE‐positive cells, and (3) the distribution of butyrylcholinesterase (BuChE)‐positive elements.The modification of Koelle's method used for AChE localization showed AChE‐positive fibers in developing parietal neocortex as early as El8–19. The distribution of AChE‐labeled fibers in the normal cortex achieves the mature pattern by the end of the third postnatal week. The rate of innervation of transplants takes longer and depends on the age of the donor tissue. Tissue from both donor ages first showed AChE‐positive fibers crossing the host‐transplant interface by 7 days postsurgery. El7–19 tissue approaches the density of AChE‐positive fibers in the normal adult cortex by 15 weeks after grafting, whereas the El2–14 donor tissue does not approach normal innervation densities until after 20 weeks. While the degree of innervation in the El2–14 donor tissue never equalled the surrounding adult cortex within our range of survival times, a few of the El7–19 transplants did develop densities equal to that of the host cortex.AChE‐positive cells are first detectable in the normal parietal cortex on the day of birth, peak by the end of the first postnatal week, and then decline in number to the low levels of the mature cortex after the second postnatal week. Grafted cells in El2–14 tissue stain lightly for AChE by 7 days postsurgery, achieve maximal densities by 3 weeks, and become markedly reduced in number and density by 10 weeks. Cells in El7–19 tissue are lightly reactive by 7 days postsurgery, reach maximal numbers by 2 weeks postsurgery, and become similar in number and density to those seen in the mature cortex after 4 weeks. The appearance of BuChE‐reactive blood vessels, neurons, and glia in both normal development and in the transplants is described and discussed.These findings indicate that embryonic neocortical tissue implanted into adult neocortex becomes innervated by AChE‐positive fibers from the host brain at different rates depending on the age of the donor tissue. Cells within the transplants express AChE transiently, similar to cortical neurons during normal development. Possible roles for the cholinergic inputs to normal and transplanted cortex are discussed.