bluuebunny/crossref_metadata_2025_split huggingface dataset:
Innervation of the guinea pig trachea: A quantitative morphological study of intrinsic neurons and extrinsic nerves
Authors: Baluk Peter , Gabella Giorgio 
Published: January 2005

AbstractThe innervation of the guinea pig trachea was studied in wholemount preparations stained for acetylcholinesterase, catecholamines, and substance P immunoreactivity and by electron microscopy. The majority of parasympathetic and afferent nerve fibres arrive from the vagus via branches of the recurrent laryngeal nerves. The recurrent laryngeal nerves are composed of several fascicles comprising 600–700 small myelinated fibres (2–5 μm diameter) and about 1,000–2,000 unmyelinated fibres; both components exit from the nerve and project in fine branches to the trachea. A separate component of 200–250 large myelinated fibres (more than 5 μm diameter) runs the full length of the nerve and innervates the striated muscles of the larynx. The recurrent laryngeal nerves are slightly asymmetric in their origin, length, number, and composition of fibres, with the right nerve being shorter but with more numerous and thinner myelinated fibres. At the distal end of the recurrent nerve, a fine branch called the ramus anastomoticus connects it to the superior laryngeal nerve. In the tracheal plexus, there are on average 222 ganglion cells (range 166–327), distributed mostly in small ganglia of 12 or fewer neurons. The ganglionated plexus is situated entirely outside the tracheal wall, overlying the smooth muscle. Ligation experiments show that sympathetic nerve fibres reach the trachea with the recurrent nerves via anastomoses between the sympathetic chain and vagus nerves, or occasionally with recurrent nerves directly, the largest being at the level of the ansa subclavia. There are also perivascular sympathetic nerve plexuses. Substance P immunoreactive fibres enter the trachea from the vagus nerves and by pathways similar to those of sympathetic nerves. There are also paraganglion cells within the recurrent laryngeal nerve that contain catecholamines and are surrounded by substance P immunoreactive fibres.After cervical vagotomy, all the large myelinated fibres of the ipsilateral recurrent laryngeal nerve degenerate and so do all but 10 or 20 small myelinated fibres and all but a few unmyelinated fibres. Degenerating fibres are found within the entire tracheal plexus, indicating bilateral innervation. The small myelinated fibres that survive cervical vagotomy probably represent sympathetic or afferent nerves with their cell bodies located in sympathetic or dorsal root ganglia.
EM autoradiographic study of the projections from the dorsal nucleus of the lateral lemniscus: A possible source of inhibitory inputs to the inferior colliculus
Authors: Shneiderman Amiram , Oliver Douglas L. 
Published: January 2005

AbstractThe fine structure of the projection from the dorsal nucleus of the lateral lemniscus (DNLL) to the inferior colliculus is examined in the cat. Anterograde axonal transport of 3H‐leucine and EM autoradiographic techniques are used to label axonal endings from DNLL. The primary finding is that axonal endings from DNLL contain pleomorphic synaptic vesicles and make symmetrical synaptic contacts. This morphology is associated with inhibitory synapses. The projection from DNLL is the source of approximately one‐third of the axonal endings with pleomorphic vesicles in the central nucleus of the inferior colliculus. In the contralateral central nucleus, only labeled endings with pleomorphic vesicles are found. By comparison, on the ipsilateral side, both endings with pleomorphic vesicles and, to a lesser degree, endings with round vesicles are labeled. Endings from DNLL are more numerous per unit area on the contralateral side. About half of the labeled axonal endings from DNLL terminate upon small dendrites, and another third terminate upon more proximal dendrites and several types of cell bodies. Many axonal endings form multiple synaptic contacts, sometimes on more than one postsynaptic structure. Sites of termination for axonal endings include dendritic spines and branch points of dendrites.These data support the hypothesis that the DNLL pathway to the inferior colliculus may have an inhibitory function. Previous studies show that DNLL neurons exhibit immunoreactivity to GAD and GABA antibodies. The crossed projection of DNLL to the inferior colliculus forms tonotopically organized bands that terminate as endings with pleomorphic vesicles. These endings may supply GABAergic inputs to the inferior colliculus. Thus, bands from DNLL could provide inhibitory inputs and overlap with bands from other sources that provide excitatory inputs. Overlapping bands may form unique synaptic domains in the inferior colliculus. The uncrossed projections from DNLL may provide the inferior colliculus with a more diffusely organized projection that could include excitatory and inhibitory inputs. Since the DNLL on one side may inhibit the opposite DNLL and the inferior colliculus, the DNLL pathway may regulate ascending inhibition to the midbrain. Presumed inhibitory inputs from DNLL to the inferior colliculus could be involved in binaural information processing and contralateral dominance.
Descending pathways to the spinal cord: II. Quantitative study of the tectospinal tract in 23 mammals
Authors: Nudo R. J. , Masterton R. B. 
Published: January 2005

AbstractTo study the early evolution of the mammalian motor systems, we have collected quantitative data on the nuclear origins of tracts descending into the spinal cord in 99 individuals representing 23 species of mammals and one species of reptile. In each individual, the spinal cord was hemisected at the C1‐C2 junction and raw HRP immediately applied to the cut fibers. After a 3‐day survival period, brain and spinal cord sections were treated with conventional tetramethylbenzidine procedures.In every case, this procedure resulted in heavy retrograde labeling of neural somata throughout the neuraxis from coccygeal cord to cerebral neocortex. Many thousands of supraspinal neurons were vividly labeled within at least 27 discrete cell groups in every mammal (Nudo and Masterton, '88). Despite the vast number and wide diversity of heavily labeled neurons, however, relatively few labeled somata were found in the superior colliculus. The total number of labeled cells in the tectum contralateral to the hemisection was highest in the cat (909) and second highest in the raccoon (628). In the remaining animals, the number was considerably less—averaging only 243 in the 23 mammalian species, 193 in the 21 noncarnivores, and 95 in the iguana. In 7 species of primates the average was 220, and in 3 species of Old World monkeys the average was 142.This wide variation in the number of tectospinal neurons is not related to body size, brain size, or absolute and relative tectum size.Arranging the animals in order of their kinship or recency‐of‐last‐common‐ancestor with Man, the average number of labeled tectal cells tends to decrease slightly, whereas arranging the same animals in order of their kinship with the cat or raccoon shows a marked and statistically reliable increase. Neither the evolutionary increase in the tectospinal tract along the Carnivora lineage nor the slight decrease along Man's lineage is altered by mathematical corrections for allometric or scaling factors. Of an array of morphological, visual, motor, and ecological traits tested statistically as a possible source of the variation in size of the tectospinal tract, only a primarily carnivorous feeding preference was found to be reliably related.The relatively small number of tectospinal fibers in most mammals in our sample, including the primates, suggests that the tectospinal tract in Man may be quite small, perhaps far too small to warrant continuing description as a “major descending tract”.
Sound‐generating (sonic) motor system in a teleost fish (Porichthys notatus): Sexual polymorphism in the ultrastructure of myofibrils
Authors: Bass Andrew H. , Marchaterre Margaret A. 
Published: January 2005

AbstractOne mechanism used by teleost fishes to produce acoustic communication signals involves the contraction of sonic “drum” muscles that appose the lateral walls of the swimbladder. In one marine species, the midshipman (Porichthys notatus), there is a sex difference in the overall size of the swimbladder as well as in the ultrastructural properties of its myofibrils. Additionally, there are two classes of sexually mature males referred to as Type I and Type II. The peripheral sonic motor system of Type I males differs from that of Type II males and females (which resemble each other) in a number of ways: 1) the mass of their swimbladder and associated sonic muscles is 50% greater, (2) their muscle fibers are several times larger and have a characteristically large volume of sarcoplasm that surrounds the myofibrils and is densely filled with mitochondria, (3) the length of z‐lines of their myofibrils is about 20‐fold greater, and (4) their sarcoplasmic reticulum is more highly branched. The ultrastructure of the myofibrils of Type II males and females resembles that found in the sonic muscle of males and females in other related species. The larger mass and specializations of the sonic muscle in Type I males are considered to be adaptations related to their known role in sound production and the unique long duration “humming” sounds that they generate during the breeding season. The similarity in the sonic motor system between females and Type II males is considered to be related to the utilization of an “alternative mating strategy” by Type II males. To our knowledge, this is the first documentation of a sex difference or, for that matter, a sexual polymorphism in the ultrastructural features of a vertebrate myofibril.
Axonal trajectory and terminal distribution of inspiratory neurons of the dorsal respiratory group in the cat's medulla
Authors: Otake Kazuyoshi , Sasaki Hiroshi , Ezure Kazuhisa , Manabe Motomu 
Published: January 2005

AbstractIn Nembutal‐anesthetized and artificially ventilated cats, we studied the morphological properties of the inspiratory neurons of the dorsal respiratory group (DRG) with HRP intracellular staining. A total of 37 neurons were stained and their axonal trajectories and terminal distribution in the medulla were analyzed. The somata were located predominantly in the ventrolateral region of the nucleus of the solitary tract and were distributed between 2,300 μm rostral and 700 μm caudal to the obex. Most (26/33) of the neurons tested were antidromically activated by the stimulation of the contralateral (n = 24) or ipsilateral (n = 2) cervical cord. To examine the existence of collateral branches in the brainstem, we traced axonal trajectories in 28 neurons. In most cases, the stem axons issuing from the cells of origin coursed ventrally and then turned medially to cross the midline without giving off any axon collaterals. However, six neurons had axonal collaterals in the brain stem ipsilateral to the somata. At least four types of collateralization were observed. The stem axon of the first type bifurcated at the area ipsilateral and ventral to the cell body. One branch crossed the midline to project to the spinal cord, and the other, thinner branch descended caudally in the ipsilateral medullary reticular formation without distributing any terminals. The axon of the second type projected to the contralateral spinal cord and distributed collateral branches with terminal boutons in the ipsilateral ventral respiratory group (VRG). The third type projected to the contralateral spinal cord and distributed terminal boutons in the medial part of the nucleus of the solitary tract (NTS) and its vicinity. The fourth type distributed numerous branches with terminal boutons in and around the ventral part of the NTS and the VRG area. This study indicates that some inspiratory neurons of the DRG influence not only spinal respiratory neurons but also medullary respiratory neurons in the vicinity of the DRG and the VRG.
Immunohistochemical distribution and partial characterization of FLFQPQRFamidelike peptides in the central nervous system of rats
Authors: Kivipelto L. , Majane E. A. , Yang H.‐Y. T. , Panula P. 
Published: January 2005

AbstractTwo peptides that are structurally related to the molluscan tetrapeptide Phe‐Met‐Arg‐Phe‐NH2 (FMRF‐NH2) were recently isolated from bovine brain extract (Yang et al.: Proc. Natl. Acad. Sci. USA 82:7757–7761, '85). These peptides have an attenuating effect on morphine‐induced analgesia when injected intracerebroventricularly in rats. Antisera against the two peptides–an octapeptide, Phe‐Leu‐Phe‐Gln‐Pro‐Gln‐Arg‐Phe‐NH2 (F8F‐NH2), and an octadecapeptide, Ala‐Gly‐Glu‐Gly‐Leu‐Ser‐Ser‐Pro‐Phe‐Trp‐Ser‐Leu‐Ala‐Ala‐Pro‐Gln‐Arg‐Phe‐NH2 (A18F‐NH2)—were raised in rabbits and characterized with standard radioimmunoassay and immunohistochemical blocking controls.This study was aimed at localizing neurons in the rat brain that contain immunoreactivity for these peptides. Cryostat sections of normal and colchicine‐treated Sprague‐Dawley rat brains were incubated with the specific antisera and the immunoreactivity was visualized by the PAP or the FITC method. Immunoreactive neurons were detected in the hypothalamus and nucleus of the solitary tract. Relatively dense networks of fibers and terminals were observed in the lateral parabrachial nucleus and in the nucleus of the solitary tract. Fibers and terminals were also seen in the lateral septum, amygdala, hypothalamus, neurohypophysis, thalamus, periaqueductal gray, and several medullary nuclei.In these areas the immunoreactivity was abolished when the antisera were incubated with the corresponding synthetic peptides F8F‐NH2 and A18F‐NH2. Preincubation of the antisera with neuropeptide Y (NPY) did not affect the staining. The results suggest that there are neurons in the rat brain that contain F8F‐NH2‐ and A18F‐NH2‐like peptides. The neuronal system described here may have a role in the regulation of autonomic functions, such as hypothalamic control and respiratory functions. The neuronal connections of the cells containing F8F‐NH2‐ and A18F‐NH2‐like peptides remain to be studied.
Mamillary body in the rat: Topography and synaptology of projections from the subicular complex, prefrontal cortex, and midbrain tegmentum
Authors: Allen Gary V. , Hopkins David A. 
Published: January 2005

AbstractThe retrograde and anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) has been used to trace afferent connections of the rat mamillary body (MB) at the light and electron microscopic levels. Injections of WGA‐HRP into different parts of the MB resulted in heavy retrograde labeling in the subicular complex, medial prefrontal cortex, and dorsal and ventral tegmental nuclei. Injections of WGA‐HRP into each of these brain regions, respectively, resulted in anterograde labeling with specific distributions and characteristic synaptic organizations in the MB. Projections from the rostrodorsal and caudoventral subiculum terminated in a topographically organized laminar fashion in the medial mamillary nucleus bilaterally, whereas afferent projections from the presubiculum and parasubiculum terminated only in the lateral mamillary nucleus. Labeled axon terminals which originated from the subicular complex were characterized by round vesicles and formed asymmetric synaptic junctions with small‐diameter dendrites and dendritic spines in the medial and lateral mamillary nuclei. Projections from the prefrontal cortex originated mainly in the infralimbic area and to a lesser degree in the prelimbic and anterior cingulate areas. Injections of tracer into these brain regions gave rise to dense labeling of axon terminals in the medial mamillary nucleus, pars medianus, and in the anterior dorsomedial portion of the pars medialis. The labeled terminals were characterized by round vesicles and formed asymmetric synaptic junctions with small‐diameter dendrites and dendritic spines. Projections from the dorsal tegmental nucleus terminated in the ipsilateral lateral mamillary nucleus, whereas afferent projections from the anterior and posterior subnuclei of the ventral tegmental nucleus terminated topographically in the medial mamillary nucleus. The ventral tegmental nucleus, pars anterior projected to the midline region of the medial nucleus and the dorsolateral and ventromedial subdivisions of the pars posterior projected to medial and lateral parts of the medial nucleus, respectively. In contrast to the synaptic morphology of subicular complex and medial prefrontal cortex axon terminals in the MB, labeled axon terminals in the MB which originated from the midbrain tegmentum were characterized by pleomorphic vesicles and formed symmetric synaptic junctions with neuronal somata and proximal dendrites as well as distal dendrites and dendritic spines. The morphological differences among axon terminals of afferent projections from the subicular complex and the medial prefrontal cortex compared to those from the midbrain tegmentum suggest that the inputs differ in terms of excitatory or inhibitory effects on MB neurons. It is proposed that cortical, subcortical, and brainstem connections of the MB form three distinct neural circuits which may represent anatomical substrates for different functional activities.
Location of forelimb motoneurons in the Japanese toad (Bufo japonicus): A horseradish peroxidase study
Authors: Oka Yoshitaka , Ohtani Ritsuko , Satou Masahiko , Ueda Kazuo 
Published: January 2005

AbstractTo label the spinal motoneurons innervating the forelimb muscles of the Japanese toad, horseradish peroxidase (HRP) was injected into these muscles or applied to the cut end of the branchial nerves (N. radialis and N. ulnaris). Spatial distribution of the HRP‐labeled motoneurons was reconstructed from serial frontal sections of the spinal cord and their location was examined.Motoneurons innervating forelimb muscles were distributed in the lateral cell column from segment 3 to segment 5 of the ipsilateral brachial spinal cord. In the transverse plane of the spinal cord, motoneurons innervating the medial forearm muscles (innervated by N. ulnaris) were located in the more medial part of the lateral cell column, whereas those innervating the lateral forearm muscles and the upper arm muscle (innervated by N. radialis) were located in the more lateral part of the lateral cell column. Along the longitudinal axis of the spinal cord, motoneurons innervating the more anterior (flexor side) forearm muscles were located in the more rostral part of the spinal cord, whereas those innervating the more posterior (extensor side) forearm muscles were located in the more caudal part of the spinal cord.Thus, motoneurons innervating forearm muscles were well organized somatotopically not only in the transverse plane, but also along the longitudinal axis of the spinal cord. Such a somatotopic organization of motoneurons along the longitudinal axis could also be regarded as a functional one; the flexor motoneurons were located rostrally to the extensor motoneurons.
Corticopontine projection in the rat: The distribution of labelled cortical cells after large injections of horseradish peroxidase in the pontine nuclei
Authors: Legg C. R. , Mercier B. , Glickstein M. 
Published: January 2005

AbstractThe distribution of cortical cells projecting to the pontine nuclei in rats was studied by making large injections of horseradish peroxidase that filled the basilar pons and measuring the density of labelled cells in each cortical area. All retrogradely labelled cells were layer V pyramidal cells. The highest densities of labelled cells were observed in the motor areas. The lowest densities were in temporal association cortex and perirhinal cortex. Visual cortical areas, including the primary visual cortex, provided a major source of pontine projections. The distribution of corticopontine cells within the primary visual cortex was studied in more detail. In all cases the highest density of labelled cells was observed in the region of cortex that represents the nasal visual field. Control injections into brainstem regions adjacent to the pontine nuclei produced a much lower absolute density of retrogradely labelled cortical cells and the distribution of those cells was different from that observed following pontine injections. We conclude that every area of the rat's cerebral cortex projects to the pontine nuclei and that there are consistent variations in the density of the projections both between and within areas.
Comparative study of glutamate decarboxylase immunoreactive boutons in the mammalian inferior olive
Authors: Nelson Barbara J. , Adams Joe C. , Barmack Neal H. , Mugnaini Enrico 
Published: January 2005

AbstractAn antiserum raised against rat glutamate decarboxylase was used to map GABAergic boutons in the inferior olive of rabbit, cat, rhesus monkey, and human. A description of the human periolivary region is also included. The inferior olive of each species contained a dense GABAergic innervation, but immunostaining intensities varied among regions. These intensities were evaluated visually and photomertrically, and the sizes and frequencies of occurence of boutons in various olivary subnuclei were measured. The beta nucleus in all species was intensely immunostained and contained the largest boutons. The caudal subdivision of the dorsal accessory olive stained with a lower intensity than the beta nucleus, but contained similarly large GABAergic boutons. By visual analysis, the rostral subdivision and the subnucleus a of the medial accessory olive and the principal olive were stained with an intermediate intensity, and these regions contained small GABAergic boutons. Photometric analysis of focal regions of the neuropil, however, revealed species differences in the staining intensity of the principal olive, which was lowest in rabbits and highest in primates. In all species, the lowest immunostaining intensity was observed in the subnucleus b of the medial accessory olive. Species variations in bouton sizes and regional staining intensities were observed in the dorsal cap and the dorsomedial cell column. The heterogeneous staining pattern and regional variation of bouton size argue for the existence of separate GABAergic projections to discrete regions of the inferior olive. Since glutamate decarboxylase immunostaining patterns in the olive are largely similar across species, the afferent projections producing these patterns may also be similar.