bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of the substance P innervation of the intermediate zone of the thoracolumbar spinal cord
Authors: Oldfield B. J. , Sheppard A. , Nilaver G. 
Published: January 2005

AbstractImmunocytochemical procedures have been used to examine the distributions of substance P (SP)‐positive fibres within the intermediate zone of the thoracolumbar spinal cords of rabbits, cats, and monkeys. In all three species SP fibres were concentrated in areas known to contain sympathetic preganglionic neurones. These included the intermediolateral nucleus and the funiculus just lateral to it, the medial gray matter in the area of the nucleus intercalatus, and the paracentral region. The density of the SP innervation varied in a characteristic way both between these subpopulations of sympathetic neurones and in its overall input to different segmental levels. Generally the greatest accumulations of SP fibres were found in the T3–T5 and L2–L4 regions and these were concentrated in the intermediolateral nucleus (ILN). The highest densities of SP fibres in the lateral funiculus were in the upper thoracic and upper lumbar segments whereas SP fibres forming transverse bands, possibly in association with neurones in the nucleus intercalatus, were most prominent in T5–T8. Substance P fibres adjacent to the midline were more or less equally dense throughout the segments examined. Substance P‐positive cell bodies situated immediately lateral to the central canal were present at a density of 200–300 per segment throughout the cat thoracolumbar cord. These neurones may be the cells of origin of at least some of the SP fibres in the intermediate zone. The close association of sympathetic preganglionic neurones with SP fibres, many of which are thought to be derived from cells in the medulla, suggests a role for SP‐containing fibres in the modulation of sympathetic activity. The variation in input to different segments and classes of sympathetic neurones further suggests a specificity which may be related to the different functions of the neurones innervated.
Cytoarchitecture and ultrastructure of the avian ectostriatum: Afferent terminals from the dorsal telencephalon and some nuclei in the thalamus
Authors: Watanabe Masami , Ito Hironobu , Ikushima Misao 
Published: January 2005

AbstractThe cytoarchitecture, ultrastructure, and afferent terminals in the ectostriatal complex of the Japanese quail were examined. The complex consists of the central core (Ec) and peripheral belt (Ep). Terminals in the complex were categorized into three main groups according to the shape of synaptic vesicles: S(spherical), P(pleomorphic), and F(flat). S terminals are further classified into three types: Ss, small terminals which have densely packed vesicles and a long active zone and are presynaptic to large spines; Sm, medium‐sized to large terminals which have a relatively short active zone and contact dendritic spines, trunks, and somata; Sl, large terminals which have many mitochondria and cored vesicles and form synapses only with somata. Some of the Sm terminals are derived from myelinated axons. The Sl terminals are frequently combined with gap junctions as so‐called mixed synapses. The P terminal occasionally surrounds an axon hillock, making symmetric synaptic contacts. The F terminals often cover a wide area of the soma. A few gap junctions are also recognized between adjacent somata.Afferent sources of the ectostriatal complex were examined by means of horseradish peroxidase (HRP) retrograde transport. Many large HRP‐labeled cells were recognized in the nucleus rotundus (Rt). HRP‐labeled cells were seen in the nucleus triangularis (Tr), nucleus dorsolateralis posterior thalami (DLP), and a few labeled cells were scattered in the hyperstriatum ventrale (HV).Substantial numbers of Sm terminals in Ec degenerated after destruction of Rt; they made synaptic contacts with dendritic trunks (71.8%) and small spines (28.2%). Degenerating and intact Sm terminals were found to form synapses with the same dendritic trunk by the reconstruction of serial thin sections. Among the 167 Sm terminals, 20 terminals (12.0%) degenerated after lesions in Rt. The Sm terminals in Ec degenerated after destruction of Tr and the terminals formed synapses with somata as well as dendritic trunks and spines. After lesions of the dorsal telencephalon including HV, degenerating fibers sparsely entered the ectostriatal complex associated with the Ss terminal degeneration. DLP seemed to project mainly on the medial area of posterior Ep. The terminals from DLP made asymmetric synaptic contacts with dendritic spines, trunks, and somata. Some of the terminals from DLP were identified as the Sl type, but other S types could not be identified.
Spinal motoneurons of the larval zebrafish
Authors: Myers Paul Z. 
Published: January 2005

AbstractApplication of horseradish peroxidase to lesions of the muscles and the central nervous system of larval zebrafish Brachydanio rerio was used to identify several types of neurons present in the spinal cord. The spinal cord was found to contain three distinct motoneuronal types: primary and secondary motoneurons that innervate the axial muscles, and pectoral fin motoneurons that innervate the muscles of the pectoral girdle. The cell types are similar to those described in larvae of other anamniote vertebrates. The axial muscles of t, given hemisegment are innervated by two or three primary motoneurons and a larger number of secondary motoneurons in the corresponding spinal segment, whereas fin muscles are innervated by a pool of motoneurons spanning several spinal segments.
Evidence for sprouting specificity following medial septal lesions in the rat
Authors: Crutcher Keith A. , Chandler John P. 
Published: January 2005

AbstractDamage to the rat septohippocampal pathway results in the growth of sympathetic axons from nearby blood vessels into the denervated hippocampal formation. Sympathohippocampal sprouting exhibits lesion specificity‐that is, only injury to the septohippocampal projection elicits the sprouting response. Whether other perivascular fibers sprout in response to septohippocampal injury (response specificity) has been addressed in the present study. Using cathecholamine histofluorescence and acetylcholinesterase histochemical techniques, we determined the distribution and incidence of perivascular sympathetic and nonsympathetic fibers associated with para‐hippocampal blood vessels in normal rats and in rats sustaining medial septal lesions. We found that sympathetic fibers are more numerous than acetylcholinesterase‐positive fibers at all septotemporal levels of the hippocampal formation and that both types are very rare at dorsal hippocampal levels in normal rats. Following medial septal lesions, however, there is a tremendous increase in the number of perivascular sympathetic fibers at dorsal hippocampal levels but no change in the number of acetylcholinesterase‐positive fibers. Electron microscopic observations indicate that the increase in perivascular fibers is due to increases in the number of sympathetic axonal fascicles as well as the number of axons per fascicle. Furthermore, both light and electron microscopic data suggest that parahippocampal veins are normally not accompanied by perivascular fibers but are associated with sympathetic fibers following medial septal lesions. These results indicate that sympathetic sprouting in response to septohippocampal denervation exhibits specificity not only in terms of the lesion which elicits such sprouting but also in terms of the types of fibers that respond to the lesion.
Electron microscopic features of physiologically characterized, HRP‐labeled fusiform cells in the cat dorsal cochlear nucleus
Authors: Smith Philip H. , Rhode William S. 
Published: January 2005

AbstractWe report on the anatomy and physiology of three fusiform cells in the dorsal cochlear nucleus (DCN) of the cat. The extra‐ and intracellular responses of these cells to pure tones showed features typical of the cell type. Peristimulus time histograms (PSTHs) were usually of the pauser or buildup configuration with chopping behavior noted in certain instances. Intracellular records during stimulus presentations revealed sustained depolarizations for the duration of the tone followed by a prolonged after‐hyperpolarization (AHP). On rare occasions, a hyperpolarization corresponding to the pause region of the PSTH was noted. Occasionally, a stimulus‐induced depolarization would be maintained after stimulus offset. Rebound excitation was also observed after the AHP. Morphologically, all three cells showed the standard fusiform cell features at the light microscopic level. The cell body gave rise to apical and basal dendritic trees. The apical tree branched frequently and displayed numerous spines distally. The basal tree had fewer branches and fewer, more irregular appendages. The axon originated from the cell body and gave rise to one or more collaterals before leaving the nucleus via the dorsal acoustic stria (DAS). At the electron microscopic (EM) level, the axon collaterals may terminate on a variety of cell types in the DCN, including fusiform cells. Their vesicles are round and the terminals closely resemble many unlabeled terminals seen on the cell body and apical and basal dendrites of our labeled fusiform cells. Terminals containing round vesicles, believed to be eighth nerve terminals, were found, with one exception, only on the basal dendrites. The spine‐laden, distal apical dendrites received primarily terminals containing round vesicles, presumed to originate from the unmyelinated axons of granule cells. The cell body and unmyelinated initial segment received mostly terminals containing pleomorphic and flat vesicles, which also made up a large percentage of the dendritic input. Some relevant correlations, between the distribution of synaptic terminals and the observed physiology, may be possible.
The midbrain periaqueductal gray in the rat. II. A Golgi analysis
Authors: Beitz Alvin J. , Shepard R. David 
Published: January 2005

AbstractThis study consists of a detailed analysis of neurons in the midbrain periaqueductal gray of the rat utilizing four variants of the Golgi technique. Neurons were classified into three major categories based on soma shape, number of primary dendrites, number of dendritic bifurcations, interspinous distance, axonal origin, and axon trajectory. Neurons in each category were further subdivided into large and small varieties based predominantly on soma size and cendritic patterns. Both quantitative and qualitative data concerning each neuronal type is provided as well as data relating to its relative distribution among the four periaqueductal gray subdivisions. The small bipolar neuron, characterized by its small size and spindle‐shaped soma, was the most prominent cell type observed, composing 37% of the impregnated neurons in our material. This cell type was most numerous in the medial subdivision and least prominent in the dorsolateral subdivision. The small triangular neuron composed 23% of the neuronal population and was relatively evenly distributed through the periaqueductal gray. The remaining four cell types include the large and small multipolar neurons, the large fusiform neurons, and the large triangular neurons. Axons originated from either the perikaryon or a proximal dendrite, with a dendritic origin being most common for large and small triangular neurons and large fusiform neurons. The trajectory of axons in single thick coronal sections originating from periaqueductal gray neurons is typically away from the mesencephalic aqueduct. The exact trajectory is dependent on the location of the neuron. Axons arising from cells in the dorsal subdivision usually project in a dorsal or dorsolateral direction while axons of ventrolateral neurons may project dorsally, laterally, or ventrally. In sum, these data indicate a complex level of internal organization of the periaqueductal gray. The results are discussed in terms of previous immunohistochemical studies of neurons in this region.
Critical stages for growth in the development of cortical neurons
Authors: Ramirez Lincoln F. , Kalil Katherine 
Published: January 2005

AbstractIn order to study the role of efferent connectivity in the development of CNS neurons, the growth of pyramidal tract neurons within the hamster sensorimotor cortex was studied during normal development and after early postnatal lesions of the pyramidal tract. We first determined, by a combination of Nissl and retrograde HRP techniques, that within the lumbar representation of cortical layer 5B in adult animals two cell populations exist: a large‐celled population (40% of the total) projecting to the spinal cord and a small‐celled population (60% of the total) projecting intracortically and to targets rostral to the medulla. We could not determine whether large layer 5B cells in the infant sensorimotor cortex also represent the corticospinal population. Nevertheless, measurements of the growth in cross‐sectional area of the large cells from 7 days postnatal to adulthood showed that these cells continue to grow until 51 days of age. The most rapid rate of growth occurs between 7 and 14 days, during which time the cross‐sectional area of the cell bodies triples, coincident with the arrival of corticospinal axons in the lumbar cord and the beginning of target innervation (Reh and Kalil, '81).The growth of the large neurons in layer 5B was then charted after the pyramidal tract was cut ipsilaterally in the medulla at various postnatal ages. Early lesions of the tract (4–8 days postnatal) interrupt lumbar projection fibers before they establish synapses in the cord. Nevertheless, cortical cell bodies in the lumbar representation continue to grow normally after axotomy until 11 days after birth. At this time, large cells are arrested in development and their cell size remains in the 11‐day stage (50% of normal adult large cell size) indefinitely. In contrast, adult lesions of the tract cause a 60% shrinkage of large cells, which in the adult represent corticospinal neurons. No evidence for cortical cell death was found after pyramidal tract lesions at any age.The results of axotomy reveal a turning point in the development of layer 5B cortical neurons. Before the age of 11 days the large cells have an independent program of cell growth that proceeds despite axotomy. After this time, the large cortical neurons appear to require intact axons for further growth and, in the absence of normal connectivity, are arrested in development.
Extent and organization of opossum prefrontal cortex defined by anterograde and retrograde transport methods
Authors: Benjamin Robert M. , Golden Gregory T. 
Published: January 2005

AbstractPrefrontal cortex is commonly defined as cortex which receives afferents from the thalamic mediodorsal nucleus (MD). The extent of opossum prefrontal cortex was mapped with anterograde and retrograde axonal transport methods. The prefrontal field was found to include not only cortex on the lateral convexity of the frontal lobe as reported in earlier studies, but, in addition, cortex within the rhinal fissure and cortex on the rostral medial wall of the hemisphere. The organization of the thalamic input to the medial wall was analyzed in some detail and compared with that of the rat. The reason for this emphasis stemmed from earlier observations which suggested that a lateral, nonolfactory segment of MD, prominent in the rat and other species, may not be present in opossum MD. In the rat, the lateral segment, which constitutes approximately one‐third of MD, projects to a relatively large expanse of rostral medial cortex which is also projected upon by the anteromedial nucleus. The main projection field of the lateral one‐third of opossum MD is to cortex on the lateral convexity of the frontal lobe which has no input from the anteromedial nucleus and has no counterpart in the rat. Only the most lateral edge of opossum MD projects to medial cortex, to a very small field, which is also projected upon by the anteromedial nucleus. In other respects, the organization of the rostral medial cortex is similar in rat and opossum. These results suggest that, rather than being absent, an equivalent of a nonolfactory segment may be present in opossum MD but is markedly reduced in size, compared to that in rat and other species.
Human fetal optic nerve: Overproduction and elimination of retinal axons during development
Authors: Provis Jan M. , Van Driel Diana , Billson Frank A. , Russell Peter 
Published: January 2005

AbstractWe have estimated the number of axons in the optic nerves of human fetuses ranging in gestational age from approximately 10 to 33 weeks. At 10–12 weeks of gestation there were an estimated 1.9 million axons in the optic nerve. A peak count of 3.7 million axons was obtained from a specimen of 16–17 weeks gestation. The estimated number of axons then declined, stabilizing at an estimated 1.1 million axons by about week 29 of gestation. This figure is in close agreement with an estimate of 1.1–1.3 million optic axons in the human adult optic nerve. The results indicate that at least 70% of optic axons generated during development of the primary visual pathway are lost during fetal life. Part of this loss probably occurs as a result of the refinement of the terminal distribution of ganglion cell projections within their target nuclei. The significance of the relatively prolonged period of axonal loss is discussed.
Topographic and laminar organization of the vagal gustatory system in the goldfish, carassius auratus
Authors: Morita Yasuhiro , Finger Thomas E. 
Published: January 2005

AbstractThe large majority of intraoral taste buds in goldfish are located on the gill arches and on the palatal organ, a muscular organ situated on the roof of the mouth. These taste buds are innervated by branches of the vagus nerve which terminate in a laminated vagal lobe, itself being an enlargement of the special visceral sensory column of the medulla. The tracer horseradish peroxidase (HRP) was used to determine the connectivity of the various branches of the vagus nerve that innervate the oropharyngeal gustatory surfaces.The entire oral cavity is mapped onto the vagal lobe so that the anterior end of the palatal organ and the most anterior gill arch are represented anteriorly in the vagal lobe; progressively more posterior oral structures are represented progressively more posteriorly in the lobe. The medial part of the palatal organ and the opposing gill arch surface, i.e., the ventromedial portion, are represented ventrally in the vagal lobe. The dorsolateral portions of the palatal organ and gill arches are represented dorsomedially in the vagal lobe. The topographic representation of the oral structures is similar for both the motor and sensory systems.In addition to this overall topographic organization, the different oropharyngeal structures are represented differentially in the layers of the vagal lobe. Palatal organ inputs reach layers VI and IX while gill arch inputs terminate in layers II, IV, and IX.The overall organization of the vagal lobe suggests a highly organized reflex system which is involved in the separation of food from substrate, especially during bottom feeding.
Sensory neuron growth cones comigrate with posterior lateral line primordial cells in zebrafish
Authors: Metcalfe Walter K. 
Published: January 2005

AbstractThe development of neuromasts and sensory neurons of the posterior lateral line was studied in zebrafish (Brachydanio rerio) in order to determine the relationship between growing axons of sensory neurons and the migratory cellular primordium of midbody line neuromasts. Scanning electron microscopy revealed that a primary system of six neuromasts develops during the second day after fertilization and evidence is presented that these arise from cells of a migratory primordium. The primordium is first detected in the postauditory region immediately adjacent to the developing sensory ganglion. Growth cones of posterior lateral line sensory neurons are found within the premigratory primordium when it is adjacent to the ganglion. At later times growth cones of these sensory neurons are found within the primordium as it migrates caudally along the midbody line.These results demonstrate that although the growth cones of the sensory neurons grow over a considerable distance to their final destination, they are never very far from their target cells (or target cell precursors), which migrate with them and may even lead them.
The transient corticospinal projection from the occipital cortex during the postnatal development of the rat
Authors: Stanfield Brent B. , O'Leary Dennis D. M. 
Published: January 2005

AbstractThe transient occipital cortical component of the pyramidal tract which we previously had identified during the postnatal development of the rat (Stanfield et al., '82) has been studied with anterograde as well as retrograde techniques. A continuous band of retrogradely labeled layer V neurons which spans the entire cortex including the occipital cortex is seen following injections of the fluorescent marker Fast Blue into the pyramidal decussation during the first postnatal week. No labeled cells are found in the occipital cortex following similar injections made on postnatal day 20 (P20), although such injections label many neurons in the more rostral cortical fields. However, if the Fast Blue injection is made on P2 and the animal is allowed to survive until P25 a large number of Fast Blue‐labeled layer V neurons is found in the occipital cortex, even though an acute, second injection of the retrograde tracer Nuclear Yellow made into the pyramidal decussation shortly before the animal is killed results in no occipital cortical labeling.When Fast Blue injections confined to the mid‐ or upper‐cervical spinal cord are made on P4 and the animals are killed on P9, again many retrogradely labeled neurons are found in the occipital cortex. Further, when injections of 3H‐proline or wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) confined to the occipital cortex are made during the first 2 postnatal weeks, anterogradely transported label is seen within the pyramidal tract. At all stages examined the amount of such label and its caudal extent are less than that seen following similar injections into the parietal or frontal cortex. The greatest extent of the labeled occipital cortical fibers is reached at about the end of the first postnatal week and the number of these fibers seems to peak at about this same time. At this stage many of these labeled axons extend for a considerable distance down the spinal cord with some reaching as far caudal as lower lumbar levels, and at this stage some of these labeled occipital corticospinal fibers enter into the spinal gray. Over the next week the number of occipital cortical fibers in the pyramidal tract rapidly decreases and by P17 occipital cortical injections of 3H‐proline or WGA‐HRP result in virtually no transported label caudal to the pons.We conclude that during the early postnatal period many layer V neurons in the occipital cortex extend corticospinal axons well down the spinal cord and some of these axons enter the spinal gray, but that all of these occipital corticospinal fibers are subsequently eliminated even though many of their neurons of origin remain intact. Thus, the elimination of long axonal collaterals appears to be an important feature of the development of cortical projection systems and plays a major role in the determination of the tangential distribution of cortical projection neurons.