bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cells of origin and terminal distrubution of corticostriatal fibers arising in the sensory‐motor cortex of monkeys
Authors: Jones E. G. , Coulter J. D. , Burton H. , Porter R. 
Published: December 2004

AbstractThe cells of origin of the corticostriatal projection have been identified in squirrel monkeys by the use of the retrograde horseradish peroxidase method. In the subfields of the somatic sensory, motor, parietal and frontal areas of the cortex, cells projecting to the ipsilateral striatum are relatively sparsely distributed and form a group of small‐ to medium‐sized pyramidal cells with an average somal diameter from area to area of 14‐16 μm. Such cells are found only in layer V of the cortex (mainly in the more superficial parts of the layer). Since they are consistently smaller than the pyramidal cells of layer V that project to the brainstem and spinal cord and since they lie outside layer VI which gives rise to corticothalamic axons, the corticostriatal axons are unlikely to be collaterals of axons projecting to other sites.The cells of origin of the'crossed corticostriatal projection are also found in layer V and are pyramidal cells with somal diameters in the same range as above. They are found only in areas 4, 8 and 6.Studies with the anterograde, autoradiographic method in rhesus, cynomologous and squirrel monkeys, indicate that the somatic sensory areas project to most of the antero‐posterior extent of the ipsilateral putamen. Subareas 3a, 3b, 1 and 2 of the somatic sensory cortex project to the same region and the projection overlaps similarly extensive projections from the motor and certain other areas of the cortex. However, in each case the pattern of terminal labeling is in the form of interrupted clusters, strips and bands. A single small injection of the cortex is associated with only one or two such clusters of terminal labeling. This seems to imply that individual corticostriatal fibers end in a very restricted manner and that the terminal ramifications of fibers from one cortical area may alternate in the putamen with those arising in other areas.
Efferent connections of cortical, area 8 (frontal eye field) in Macaca fascicularis. A reinvestigation using the autoradiographic technique
Authors: Künzle H. , Akert K. 
Published: December 2004

AbstractThe efferent projections from the cortical area 8 (frontal eye field) have been re‐examined in four adult monkeys (Macaca fascicularis) by injecting small amounts of H3 ‐proline into the rostral bank of sulcus arcuatus and using the autoradiographic tracing technique. Ipsilateral cortical projections could be traced into specific areas of the depths of sulcus principalis, sulcus temporalis superior and sulcus intraparietalis. Label was found contralaterally in area 8. Subcortical connections were observed ipsilaterally to n. caudatus, putamen, claustrum, n. ventralis anterior pars magnocellularis, n. medialis dorsalis pars multiformis and pars densocellularis, n. centralis lateralis and paracentralis, n. parafascicularis, n. pulvinar oralis, zona incerta, n. subthalamicus, pretectal area, colliculus superior and griseum pontis as well as to the ipsi‐ and contralateral n. reticularis tegmenti pontis. Negative results were obtained with respect to the oculomotor nuclei, n. interstitialis and Darkschewitsch as well as to the paramedian pontine reticular formation.
The development of monoamine‐containing neurons in the brain and spinal cord of the salamander, Ambystoma mexicanum
Authors: Sims Terry J. 
Published: December 2004

AbstractThe distribution of monoamine‐containing neurons in the CNS of the developing and adult axolotl, Ambystoma mexicanum, has been investigated using the histochemical fluorescence technique of Falck and Hillarp combined with microspectrofluorimetry. The earliest catecholamine‐containing neurons to be detected are located in the ventral ependymal zone of the spinal cord at the time of hatching (Stage 41). Between stages 43 and 46, catecholamine fluorescence can be detected in neurons in the following regions: nucleus preopticus, the hypothalamic‐infundibular region, and the brain stem reticular fomation. 5‐HT‐containing neurons are only observed in the midbrain raphe region and are first detected at stage 44. In contrast to these early monoamine fluorescing groups, catecholamine‐containing neurons are not routinely detectable in the nucleus interpeduncularis until six months of age. All monoamine‐containing neuronal groups detected in developing axolotls are also present in both sexes of the adult. However, the fluorescence intensity is less in monoamine‐containing neurons observed in adults than in early developing subjects.All catecholamine‐containing neuronal groups, with the exception of those located in the midbrain region (nucleus interpeduncularis, reticular zone) have fluorescent processes that contact the cerebrospinal fluid (CSF). The presence of CSF‐containing processes in the hypothalamic and spinal cord regions suggest that the CSF may act as a medium through which bioactive substances are transported from one brain region to another. Intense catecholamine fluorescence is observed in cells of the notochord prior to the detection of monoamine‐containing neurons in the CNS. A possible involvement of catecholamines in the inductive effects of the notochord during development is discussed.
The organization of the dorsal root entry zone in cats and monkeys
Authors: Snyder Russell 
Published: December 2004

AbstractIn five adult cats and three adult monkeys the dorsal rootlets at cervical and various lumbar levels were examined by both light and electron microscopy. In both species, the rootlets could be divided into three anatomically distinct parts: a peripheral, a transitional, and a central zone. The anatomy of the peripheral and transitional parts of the cat were identical with those of the monkey. The peripheral part of the rootlet in both these species had many of the ultrastructural characteristics of a peripheral nerve: and, as in the peripheral nerve, the small caliber axons were randomly distributed throughout the rootlet. In the transitional part of the rootlet, where the anatomical characteristics change to those typifying the tracts of the central nervous system, the unmyelinated axons and small caliber myelinated axons become organized into bundles at the periphery of the fascicles of large myelinated axons. In the central part there were differences between the two species in the distribution of the unmyelinated axons. In the cat no reorganization of the fibers of the central part of the rootlet could be found: the rootlets entered the cord and passed through the dorsal part of Lissauer's tract, and the bundles of unmyelinated axons simply merged with the tract as they came into contact with it. In the monkey, however, the dorsal root enters dorsal to Lissauer's tract and as each part of the rootlet passed from transitional to central, the small caliber axons took a ventrolateral course within the rootlet. As the rootlet merged with the dorsal columns, these axons formed a single bundle on the ventral and lateral surface of the rootlet which then merged with Lissauer's tract. These results indicate that a “lateral division” of the dorsal root is present in the monkey, but not the cat.
The lateral reticular nucleus of the opossum (Didelphis virginiana). I. Conformation, cytology and synaptology
Authors: Andrezik Joseph A. , King James S. 
Published: December 2004

AbstractWhen viewed in Nissl preparations, the lateral reticular nucleus (LRN) of the opossum can be divided into three subgroups: a medial internal portion, a lateral external portion and a rostral trigeminal division. Neurons within the internal division measure 13‐45 μ in their greatest dimension whereas those within the external and trigeminal portions measure 11‐32 μ and 14‐27 μ respectively.Golgi impregnations reveal that many neurons in all three subdivisions display a radial dendritic pattern although some of the nerve cells within the external division have dendrites which orient mainly in a ventromedial to dorsolateral direction. The cell bodies of LRN neurons are relatively spine‐free. However, a small percentage of neurons exhibit clusters of sessile spines on proximal and more distal dendritic segments. No locally ramifying axons or axon collaterals were found within the LRN.Synaptic terminals within the LRN were divided into four categories: (1) small terminals measuring 2.5 μ or less containing agranular spherical vesicles; (2) small terminals (2.5 μ or less) with agranular pleomorphic synaptic vesicles, i.e., a mixture of spherical and elliptical synaptic vesicles; (3) small terminals (2.5 μ or less) containing agranular spherical or pleomorphic vesicles with a variable number (4‐27) of dense core vesicles; and (4) large terminals (greater than 2.5 μ) which contain agranular spherical synaptic vesicles and a variable number of dense core vesicles (1‐17).Dendritic diameters were measured from Golgi impregnations and correlated with cross‐sectioned profiles in electron micrographs to help determine the post‐synaptic distribution of synaptic endings. Small terminals containing agranular spherical or pleomorphic synaptic vesicles contact the soma and entire dendritic tree in each portion of the nucleus, whereas the small terminals containing dense core vesicles are usually located on distal dendrites or spines. Some large terminals make multiple synaptic contacts with a cluster of spines, others contact groups of small (distal) dendrites.In order to identify two of the major afferent systems to the LRN, 15 adult opossums were subjected to either a cervical spinal cord hemisection or a stereotaxic lesion of the red nucleus. Two days subsequent to spinal hemisection, large terminals in the caudal part of the ipsilateral LRN exhibit either an electron dense or filamentous reaction. Their postsynaptic loci are spines and shafts of proximal dendrites or a number of distal dendrites and spines. In addition, small terminals containing spherical agranular synaptic vesicles undergo an electron dense reaction in the same areas. Their postsynaptic loci are proximal or distal dendrites. Two days subsequent to rubral lesions, small terminals containing agranular spherical synaptic vesicles undergo a dark reaction in rostral portions of the contralateral nucleus. They contact intermediate or distal dendrites and occasionally spines.
Fiber counts of regenerating peripheral nerves in axolotls and the effect of metamorphosis
Authors: Ehrlich D. , Mark R. F. 
Published: December 2004

AbstractCounts have been made of myelinated and unmyelinated fibers in the sixteenth nerve root of the axolotl, before, during and after regeneration following nerve section. There is no loss of myelinated fibers. Many collateral sprouts are formed and eventually withdrawn. Regeneration during metamorphosis is similar but there is more sprouting. There is no fiber loss from cut nerves in metamorphosis. This suggests that rising thyroid hormone levels are not in themselves detrimental to nerves without peripheral connections. Other factors that may govern cell loss in limb development are discussed.
Amygdaloid and pontine projections to the ventromedial nucleus of the hypothalamus
Authors: McBride Russell L. , Sutin Jerome 
Published: December 2004

AbstractAmygdaloid and pontine projections to the feline ventromedial nucleus of the hypothalamus (HVM) were studied with retrograde transport of horseradish peroxidase (HRP) and anterograde transport of tritiated amino acids. Following injections of HRP into HVM, amygdaloid neurons were labeled in the ipsilateral cortical and medial nuclei and the ventral portion of the parvocellular part of the basal nucleus. In experiments in which HRP was injected into the tuberal hypothalamus following stria terminalis lesions, it was determined that amygdaloid neurons projecting to HVM by way of the stria terminalis were located in the cortical and medial nuclei while those projecting through another route, presumably the ventral amygdalofugal pathway, were found in the rostral part of the medial nucleus and the parvocellular basal nucleus.Following HRP injection into lateral hypothalamus at the level of HVM, labeled neurons were seen in the magnocellular basal nucleus. After preoptic injections, neurons containing the HRP reaction product were in cortical and medial nuclei and magnocellular and parvocellular parts of the basal nucleus.In addition to cells in the amygdala, rostral pontine neurons were labeled after HRP injections into HVM. The cells were located ipsilateral to the injection, mostly in the dorsal nucleus of the lateral lemniscus, lateral and dorsolateral to the brachium conjunctivum. The pontine cells labeled following HVM injections of HRP were different from those labeled following lateral hypothalamic and preoptic region injections. The pontine projection to HVM was confirmed using axoplasmic transport autoradiography. A mixture of tritiated leucine and tritiated proline was injected into the lateral pontine region labeled after HRP injections into HVM. Labeled axons ascending in the medial forebrain bundle terminated throughout the rostro‐caudal extent of HVM.
Interlaminar connections of rat visual cortex: An ultrastructural study
Authors: Butler Albert B. , Jane John A. 
Published: December 2004

AbstractThermal lesions were made in layers I, II, and upper part of layer III of rat visual cortex. The distribution of degenerating axons and axon terminals in layers IV, V, and VI was studied using electron microscopic techniques.Following supragranular thermal lesions, the majority of degenerating axon terminals were found in layer V, with extension into the adjacent part of layer VI. Neural profiles postsynaptic to degenerating axon terminals were found in these layers in the following distribution: 81.7% on spines of small to medium size dendrites; 18.2% on dendrite shafts; and <1% on neuronal perikarya. Few degenerating terminals were found on or near apical dendrites. Degenerating terminals were identified on shafts of stellate‐type dendrites found in the upper part of layer V.Degenerating axons oriented parallel to the cortical surface were found most often in deep layer IV and upper layer V. Degenerating axons were also seen in axon bundles coursing vertically through layer IV.Approximately 10% of the terminals within a grid square have undergone degeneration; no clustering of degenerating terminals was found in vertical or transverse sections through layers V and VI.We suggest that most axon terminals arising from pyramidal neurons in layers II and upper III synapse with spines and shafts of dendrite branches originating from pyramidal neurons in layer V and perhaps VI.
Retinofugal projections in the lepidosirenid lungfishes
Authors: Northcutt R. Glenn 
Published: December 2004

AbstractAutoradiographic and silver methods indicate that the African and South American lungfishes, Protopterus and Lepidosiren, lack ipsilateral retinal projections. Contralaterally, the retina projects to the preoptic nucleus of the hypothalamus, to four discrete areas located in the lateral neuropil of the thalamus, to a superficial pretectal neuropil, to the upper half of the tectal neuropil, and to a laterally situated basal optic neuropil located in the rostral tegmentum. The overall pattern of the primary retinofugal projections is markedly similar to that of amphibians which suggests that lungfishes may be more closely related to amphibians than to actinopterygian fishes. Neotenic trends in both lepidosirenid lungfishes and urodeles may be expressions of parallelism, hence Latimeria and Neoceratodus must be examined to resolve this phylogenetic problem. A 300‐fold range in the size of the eye, indicated by the number of ganglion cells present, occurs among lungfishes, salamanders and frogs. This variation may have implications for recognizing the morphological expression of selection operating on the visual systems of lepidosirenids and amphibians.
Commissural connections of the dentate area in the rat
Authors: Hjorth‐Simonsen A. , Laurberg S. 
Published: December 2004

AbstractThe commissural connections of the area dentata were investigated with the Fink‐Heimer silver impregnation method and the commissural terminals in the hilus of the fascia dentata further studied by electron microscopy of anterograde degeneration.The commissural endings in the molecular layer were found to terminate as previously reported by others. In addition it was shown that the hilus also receives a significant commissural input. The commissural afferents to both the molecular layer and the hilus terminate along the full rostro‐caudal extent of the area dentata, but with varying densities. The degeneration in the molecular layer is maximal dorso‐rostrally and declines in the caudo‐ventral direction, whereas the degeneration in the hilus varies inversely.The commissural terminals in the hilus make asymmetrical contacts with dendritic spines and to a lesser extent with dendritic stems. Dark, but otherwise apparently normal terminals with the features of mossy fiber boutons, were encountered in low numbers in both decommissurated and control animals. The commissural projection to the dentate area originates in the opposite hilus and possibly the adjacent part of CA3 (CA3c). Fibers from middle dorso‐basal levels of the hilus to the opposite molecular layer are distributed more rostrally than ventrally relative to the level of the source of the fibers.
Cerebellar corticonuclear and corticovestibular fibers of the flocculonodular lobe in a prosimian primate (Galago senegalensis)
Authors: Haines D. E. 
Published: December 2004

AbstractEfferent projections from the flocculonodular lobe and the ventral part of the uvula were studied in a prosimian primate (Galago senegalensis) utilizing the Fink and Heimer (1967) method. Corticonuclear and corticovestibular fibers of the flocculonodular lobe and ventral uvula are ipsilateral. Fibers from both the flocculus and nodulus appear to terminate in cell group y (of Brodal and Pompeiano, 1957) although there is little evidence of other projections beyond the vestibular complex. The cortex of the flocculus sends numerous fibers into ventral portions of the NL, central areas of the SVN, and rostral and ventral regions of the MVN and fewer fibers into dorsal and medial SpVN. Many fibers from the nodulus terminate in ventrocaudal NM, peripheral areas of the SVN, and dorsal and caudal MVN. Fewer fibers course into ventral areas of the ipsilateral NL and in approximately the dorsal half of the SpVN and in its ventrolateral area at caudal levels. The LVN receives few, if any, fibers from the flocculonodular lobe. When present they appear to end almost exclusively in those areas of the LVN which border the SVN, MVN, or SpVN. The ventral uvula sends fibers mainly to the dorsomedial SVN, throughout the dorsal SpVN and in its ventrocaudal area, and to a limited region of the ventrolateral MVN at caudal levels. A few fibers from the ventral uvula distribute to dorsolateral SVN, to central areas of the caudal SpVN, and to the ventral MVN at caudal levels.Corticonuclear and corticovestibular fibers of the flocculus, nodulus and ventral uvula are (1) topographically organized with respect to their specific nuclei of termination and (2) have terminal fields in the cerebellar nuclei and vestibular complex which are partially coextensive (with the terminal field of one or both of the other lobules) and partially exclusive (to that particular lobule). Projections are seen into ventral portions of the ipsilateral NL from both floccular (hemisphere) and nodular (vermis) cortices. It is postulated that this may represent a direct route through which the flocculonodular cortex may assist in the regulation of eye movement since the primate NL, expecially its ventral part, sends fibers to certain of the contralateral oculomotor nuclei via the crossed ascending limb of the brachium conjunctivum (Carpenter and Strominger, 1964; Martin et al., 1974; Chan‐Palay et al.,1976).
Experimental evidence for climbing fibers in the avian cerebellum
Authors: Freedman S. L. , Voogd J. , Vielvoye G. J. 
Published: December 2004

AbstractThis study identifies climbing fibers in the cerebellar cortex following brain stem lesions. Antegrade nerve fiber degeneration was studied after electrolytic destruction of rhombencephalic structures in 24 domestic fowl. Direct damage to the cerebellum was precluded by a retropharyngeal surgical approach. Only lesions that include the inferior olivary nucleus were compatible with Fink‐Heimer staining of degenerating nerve fibers in the Purkinje cell and molecular layers. Degenerating axons were identified as climbing fibers from their trajectory in association with Purkinje cell soma and dendrites. Terminal nerve endings were observed only in the basal one‐third to one‐half of the molecular layer. The presence of climbing fibers in only the contralateral molecular layer was observed in autoradiographic preparations subsequent to unilateral injection of tritiated leucine into the inferior olivary nucleus of three hens. The morphology of the labeled and impregnated degenerating nerve fibers closely coincides with information provided by previous investigators using Golgi stained histological preparations and electron microscopy.
Scanning electron microscopy of the third ventricular floor of the rat
Authors: Paull W. K. , Martin H. , Scott D. E. 
Published: December 2004

AbstractBy utilizing a horizontal dissection technique the entire floor of the third ventricle has been examined. When viewed in toto the ventricular floor was seen to have an hourglass shape with the supraoptic and infundibular recesses equalling the widened portions. Consistent regional differences were also noted. The rostral half of the floor was densely ciliated while the caudal portion, containing ependymal elements of the underlying median eminence, possessed few cilia. The ciliated cells ended in an abrupt transition zone located about halfway along the floor. The rostral portion of the infundibular recess had many more apical blebs and microvilli than did the caudal areas. Supraependymal cells of both the phagocyte‐like and neuron‐like variety were observed in all of the animals examined. In some animals, complex, branching, interconnecting networks of fine calibered fibers interconnected neuron‐like cells that occurred singly and occasionally in clusters. Female rats examined at all phases of the estrus cycle demonstrated no cyclic alterations of the ependymal surface.
Orientation of slit pupil and visual streak in the eye of the cat
Authors: McIlwain James T. 
Published: December 2004

AbstractThe orientation of the visual streak of the cat's retina was compared to that of the long axis of the slit pupil in the same eye. In five paralyzed, anesthetized cats, the retinal projection to the superior colliculus was mapped with electrophysiological techniques. The orientation of the visual streak was estimated from the projection in visual space of the collicular region of high magnification which corresponds to the central projection of the streak. The angle by which the streak was tilted from absolute horizontal was always within one or two degrees of the angle by which the pupil axis was tilted from absolute vertical. This relationship was confirmed in three of the animals in which small retinal lesions were placed a known distance from the histologically determined axis of the streak. From the visual coordinated of these lesions, an independent estimate of the streak's orientation was obtained. In each case, the tilt of streak axis from horizontal differed by no more than 0.5° from the tilt of the pupil axis from vertical. The results support the hypothesis that planes containing the long axis of the cat's slit pupil are perpendicular to planes containing the long axis of the visual streak of the same eye.