bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fine structure of neurons and synapses in the entopeduncular nucleus of the cat
Authors: Adinolfi Anthony M. 
Published: December 2004

AbstractCat brains were fixed by vascular perfusion with glutaraldehyde and paraformaldehyde and the entopeduncular nucleus was examined by electron microscopy. The fine structure of most neurons in this region does not significantly differ from earlier descriptions of large neurons. Distinctive features of perikarya and dendrites include juxtanuclear Nissl bodies, unique lamellar configurations composed of agranular cisternae separated by thin layers of dense granular matrix and continuous with the granular endoplasmic reticulum, localized swellings of dendrites, and dendritic branchlets or gemmules which invaginate a single nerve terminal. Cell surfaces are ensheathed by interdigitating nerve terminals and glial lamellae. Two types of endings are distinguished on the basis of their diameter and the size of their synaptic vesicles. Further division depends on distribution of the vesicles within a terminal, where the synapses occur, and the presence of postsynaptic bodies. Most terminals are about one micron and contain closely packed synaptic vesicles measuring 515 Å (S. D. 72.7 Å). Larger terminals containing fewer smaller (312 Å) synaptic vesicles and neurofilaments or neurotubules near the periphery have been interpreted as boutons‐en‐passage. It is suggested that different afferent projections end in a similar manner on restricted portions of the neuronal surfaces in the entopeduncular nucleus.
The cortico‐thalamic projections from the sensorimotor cortex of Galago crassicaudatus
Authors: Campos‐Ortega J. A. , Clüver P. F. de V. 
Published: December 2004

AbstractThe cortico‐thalamic pathways from the sensorimotor cortex of the prosimian Galago crassicaudatus were studied after cortical lesions. The Glees method and several modifications of the Nauta technique were used. A short description of the thalamic nuclei in Galago is given. The motor cortex was found to project to the following nuclei: reticularis thalami, lateralis anterior, lateralis ventralis oralis, lateralis dorsalis intermedius, the pars paralamellaris of the nucleus lateralis ventralis posterior, the intralaminar nuclei, parafascicularis‐centrum medianum complex, lateral third of the mediodorsalis, praetectalis, zona incerta, H fields of Forel and the subthalamic nucleus. The cortical projections to nucleus centrum medianum was found to be topically organized.The sensory cortex was found to project to the following nuclei: reticularis thalami, lateralis dorsalis intermedius, paracentralis, parafascicularis, pars lateralis and pars medialis of the nucleus lateralis ventralis posterior, praetectalis, posterior, zona incerta, and the H fields of Forel. The topical organization of the cortical projection to the lateral complex and posterior nucleus is discussed.
An autoradiographic study of the development of the anterior thalamic group and limbic cortex in the rabbit
Authors: Fernández Victor 
Published: December 2004

AbstractUsing autoradiographic technique the migratory movements of cells destined to form the anterior thalamic nuclear group and the limbic cortex were studied in 54 embryos or newborn rabbits the mothers of which were injected with a single dose of tritiated thymidine on the fifteenth to twenty‐fifth day of gestation.Neurons which form the anterior thalamic group originate between the fifteenth and eighteenth day of gestation. An orderly relation exists between the time of origin of the anterior thalamic neurons and their definitive position within the dorsal thalamus. The cells which originate earliest lie most laterally in the dorsal thalamus; those which originate later lie successively more medially. No nucleus in the anterior group is isochronic in regard to the origin of its cells and in each a latero‐medial gradient corresponding to early‐late origin is apparently present.Neurons forming the limbic cortex (upon which the anterior thalamic group projects) originate between the fifteenth and twenty‐fifth day of gestation. The anterior and the posterior limbic regions seem to develop synchronously. In agreement with other workers it is concluded that neurons which originate earliest form the VIth layer of the differentiated cortex while those which originate later form successively the more superficial cortical layers. No retrograde movements of the migrating cells were observed. It is suggested that during cortical development each migratory wave of cells, after passing the thickness of the already existing cortical plate, constitutes at some stage the most superficial cell layer of the then existing cortex.
Development of neuronal connections with skin grafts in frogs: Behavioral and electrophysiological studies
Authors: Jacobson Marcus , Baker Robert E. 
Published: December 2004

AbstractThree types of skin grafts were made in frog tadpoles at various stages of development. Skin on the trunk was excised and replaced in a back‐to‐belly inverted position; or skin on the back was grafted in a head‐to‐tail inverted position; or small patches of back and belly skin were exchanged. During metamorphosis these animals devloped normal reflexes in response to stimulating the skin graft. Some days later, reflexes misdirected to the original position of the grafted skin occurred on stimulating back‐to‐belly inverted grafts made before larval stage XV. The area of skin giving rise to misdirected reflexes enlarged gradually to occupy most of the graft. Only normal reflexes were elicited from back‐to‐belly inverted grafts made after stage XV and from the other types of grafts made after stage I. Misdirected reflexes were permanent. However, re‐rotation of back‐to‐belly inverted grafts in adult frogs resulted in recovery of normal reflexes in some cases.The receptive fields of cutaneous nerves were mapped electrophysiologically and were similar in tadpoles and frogs with skin grafts and normal controls. No changes in receptive fields were detected during development of during the period when normal or misdirected reflexes appeared. We concluded that misdirected reflexes were not caused by changes in the peripheral receptive fields but were due to changes in the central nervous system which occurred after the sensory nerves had connected with the skin graft.
Ansa and fasciculus lenticularis of carnivora
Authors: Grofová I. 
Published: December 2004

AbstractThe fiber systems of the globus pallidus and the nucleus entopenduncularis were studied in normal brains of the cat and of the brown bear, stained by the Häggqvist method.The globus pallidus in both animals is traversed by bundles of the internal capsule. No division into external and internal segments can be made. Pallidal fibers do not form fascicles resembling the ansa or fasciculus lenticularis of primates. They are thicker in the bear (3.5–5 μ) than in the cat (2–3.5 μ).The entopeduncular nucleus in the bear is prominent and lies close to the globus pallidus. Fibers arising in its grey network are rather thick (5–6.5 μ) and at its rostral level assemble to form the ansa lenticularis. Subsequently they traverse the internal capsule in slender ribbons to assemble again in the fasciculus lenticularis. Corresponding fibers in the cat are thinner (3–4.5 μ) and do not form distinct fascicles. Their course resembles that in the bear but they reach Forel's field rostral to the subthalamic nucleus. The fasciculus thalamicus and fasciculus pallidohypothalamicus are composed of these fibers.Edinger's comb system is well developed in both animals. Its dorsal part consists of pallidal fibers, representing the fasciculus pallido‐subthalamicus. The findings furnish further evidence that the nucleus entopeduncularis actually represents the internal pallidal segment of the primates.
Changes in nerve cell bodies during the myelination of their axons
Authors: Julio Martinez A. , Friede Reinhard L. 
Published: December 2004

AbstractChanges in nerve cell perikarya were studied at twelve phases of the myelination period of rat sciatic nerve; data are given on nuclear and nucleolar diameters, the area of cytoplasm, neuronal packing density, length of the nerve, limb and femur, and on the distribution of chromophil substance in the cytoplasm. The study was coordinated with and supplements a previous quantitative electron microscopic study of myelination in rat sciatic nerve.The amounts of cytoplasm in anterior horn motor cells and in large cells of the spinal ganglia increased during myelination, and growth curves for these two cell populations were nearly identical. The increase in cytoplasm was compared with the increase in axoplasm, calculated from the increase in caliber and in fiber length. The volumes of axoplasm and of cytoplasm in the perikarya increased in strict proportion, indicating a coordinated growth of axons and perikarya during the myelination period. Axon growth in turn, occurs in strict coordination with myelin deposition.The growth curve for the small cells in spinal ganglia differed entirely and is consistent with the assumption that nonmyelinated or very thinly myelinated fibers arise from these cells. Changes in the volume of cytoplasm in nerve cells were associated with changes in the nucleo‐cytoplasmic relation, a decrease in neuronal packing density, and a redistribution of RNA in the cells.
The fine structure of the circumesophageal nerve in several decapod crustaceans
Authors: Skobe Ziedonis , Nunnemacher Rudolph F. 
Published: December 2004

AbstractIn order to obtain a better understanding of the significance of the anatomy of the crustacean nervous system with respect to behavior entire cross sections of circumesophageal connective nerves were examined by electron microscopy to determine the number and diameter of nerve fibers in the following species: Crangon septemspinosa, Pagurus pollicaris, P. longicarpus, Carcinus maenas, Cal. linectes sapidus, Podophthalmus vigil, Cancer irroratus, C. borealis, Grapsus grapsus, Gecarcinus lateralis, Uca pugnax, and Libinia emarginata. The diameter of the fibers ranged from 0.1 μ to 80 μ; in each case the larger fibers being in the dorsal portion of the connective. In most species the smaller fibers were most numerous; with increasing diameter the fibers became less numerous. The total number of fibers ranged from 1,500 to 9,600. This interspecies difference is primarily due to variance in the number of very fine fibers. Unusual patterns of fiber distribution appeared in Crangon and Callinectes, which had no fibers of very small diameter, in Pagurus with a large bundle of such fine fibers, and in Grapsus, which had several giant fibers. In some of the species the peculiar fiber distributions appear to be related to particular adaptations.
Efferent connections of the periaqueductal gray matter in the cat
Authors: Hamilton Betty L. , Skultety F. Miles 
Published: December 2004

AbstractElectrolytic lesions were stereotaxically placed in the dorsal and ventral areas of the mesencephalic periaqueductal gray in the cat. A dorsal angular approach was made so that mechanical electrode damage was contralateral to the lesion, or a posterior approach through the fourth ventricle was employed to avoid electrode damage. The brains were sectioned coronally and sagittally and stained with a modifield Nauta‐Gygax or Fink‐Heimer stain.Degeneration from the dorsal lesions was chiefly in a radial pattern to the superior colliculus, inferior colliculus and mesencephalic reticular area. Also, fibers angled out of the dorsal gray, crossed the midline and joined the commissure of the superior colliculus, some taking a ventrolateral course through the colliculi and others running ventrally along the borders of the gray. Degeneration was traced caudally to the cuneiform nucleus and adjacent reticular area. Rostrally, fibers traveled in the dorsal longitudinal fasciculus to the pretectal area, lateral habenular nucleus and finally, the posterior hypothalamic area.Ventral lesions showed the same radial pattern of degeneration and fibers in the superior colliculus commissure. Caudally, fibers could be traced to the cuneiform nucleus, reticular area and inferior olive. The rostral course of fibers in the dorsal longitudinal fasciculus was similar, though there were additional connections with the ventral tegmental area of Tsai, the fields of Forel, and the parafascicular nucleus of the thalamus.
The corticospinal tract of the marsupial phalanger (Trichosurus vulpecula)
Authors: Martin George F. , Megirian David , Roebuck A. 
Published: December 2004

AbstractThe origin, course and distribution of corticospinal fibers were determined in the marsupial phalanger (Trichosurus vulpecula) by the use of the Nauta‐Gygax technique. Findings in 15 cases of cortical lesions indicated that corticospinal fibers arose mainly within the immediate postorbital and midcortical (parietal) regions and descended throughout the ipsilateral pyramidal bundle. The great majority of the fibers cross in the caudal medullary pyramidal decussation. At spinal cord levels, such fibers compose a large dorsal corticospinal tract located ventrally within the dorsal funiculus and a smaller lateral bundle descending in the medial part of the lateral funiculus. Even in cases of complete unilateral decortication, degenerating corticospinal fibers could be traced only as far caudally as T–10.At cervical levels, the majority of cortiospinal fascicles arborize within the medial portions of Rexed's laminae III through VI. A smaller contingent of fibers extends into the lateral portions of these same laminae. Of particular note were corticospinal fibers which appeared to end within lamina VII and, to some extent, within lamina VIII. Many of the fibers ramifying within lamina VII did so in close proximity to the motor neurons of lamina IX; none, however, could be identified within the confines of lamina IX. At thoracic levels, where lamina VI is indistinct, terminal degeneration of rapidly decreasing amount appeared within the medial portions of laminae IV, V and VII. At more caudal thoracic levels, the area of apparent corticospinal fiber termination was limited mainly to the medial and, to a much less extent, the lateral portions of lamina V.
A study of the median giant fiber system in the cephalic ganglion of a crayfish (Procambarus clarkii)
Authors: Horiuchi Etsuko , Hayashi Hideo , Takahashi Isao 
Published: December 2004

AbstractThe pathway of the median giant fiber in the crayfish cephalic ganglion (brain) was reconstructed from serial sections. The median giant fiber in the para‐esophageal nerve runs anteriorly and enters the brain. After turning medially, it given of a branch which further divides into two branches. These branches run ventrally and outwards and finally enter the ipsilateral antennule nerve and ventrally. It decussates and makes contact with the contralateral median giant fiber near the midline. After decussating, the fiber again divides into two branches. One runs outwards and ventrally and finally enters the contralateral antennule nerve. The other runs anteriorly at first and then turns ventrally immediately behind the rostral cellular group. Near the ventral surface of the brain the fiber turns posteriorly and connects with a large soma 100–150 μ in diameter. In its course to the soma, the main fiber decreases in width to one‐eighth of the diameter of the axon in the para‐esophageal nerve.
The corticopontine projection in the cat. I. The projection from the proreate gyrus
Authors: Brodal Per 
Published: December 2004

AbstractFollowing large and small lesions (in many cases bilateral) of the proreate gyrus in adult cats the ensuing degeneration in the pontine nuclei was studied with the silver impregnation methods of Nauta and of Fink and Heimer. Lesions were produced by transdural thermocoagulationThe main results are as follows:
All parts of the proreate gyrus on the convexity of the hemisphere emit fibers to the pontine nuclei. The projection from the dorsal part is somewhat less intense than that from the ventral part. The density of projection from the proreate gyrus is far less than from the anterior sigmoid gyrus (motor cortex).
The proreate gyrus projects upon two longitudinal columns in the ipsilateral pontine gray. One column is located medially, the other laterally.
The exact localization of these columns has been compared with the localization of the columns projected upon by the anterior sigmoid gyrus. No clear difference has been found.
No topical localization could be demonstrated within the pontine projection from the proreate gyrus, which in this respect differs from the projection from the anterior sigmoid gyrus (motor cortex), which projects somatotopically upon both columns. Possible relations between the proreate gyrus and the cerebellum are discussed.
The corticopontine projection in the cat. II. The projection from the orbital gyrus
Authors: Brodal Per 
Published: December 2004

AbstractFollowing large and small lesions of the orbital gyrus in adult cats the ensuing degeneration in the pontine nuclei was studied with the silver impregnation methods of Nauta and of Fink and Heimer. Lesions were produced by transdural thermocoagulation. The main results are as follows:
All parts of the orbital gyrus give off fibers to the pontine nuclei. The density of projection is less than from the anterior ectosylvian gyrus (second somatosensory area).
The orbital gyrus projects upon four longitudinal columns within the pontine nuclei. One is located medially, one ventromedially, one ventrolaterally and one dorsolaterally.
The exact localization of these columns has been compared with the localization of the columns projected upon by the anterior ectosylvian gyrus. Three of the columns (the medial, ventrolateral and dorsolateral) appear to be projected upon by both gyri, while the fourth one receives afferents from the orbital gyrus only.
A topical localization exists within the projection from the orbital gyrus insofar as the anterior part of the gyrus projects onto the medial, ventrolateral and dorsolateral columns, while the posterior part projects onto the ventromedial column mainly.
Whether a somatotopical localization is present within the projection to some or all of the columns can not be decided from the material.
Classification of neurons in the ectosylvian auditory cortex of the dog
Authors: Tunturi Archie R. 
Published: December 2004

AbstractThe rapid Golgi method was used to classify the neurons in the MES and PES auditory areas of the dog. Small pyramids were found in layer II with percentages of 12% in the MES area and 8.1% in the PES area. Medium sized pyramids possessed a bimodal distribution, the first in layer IV and the second in V, with 58% in MES and 62% in PES. Large pyramids were found in layer V with a proportion of 12.5% in MES and 17% in PES. The star neurons were found in layer III with proportions of 5.9% in MES and 4.0% in PES. The double bouquet neurons in layer III had a proportion of 1.5% in MES and 1.7% in PES. Fusiform neurons in layers V and VI were in proportions of 2.2% in MES and 6.4% in PES. The principal finding was a special auditory cell occurring in layers V and VI of the MES area with a proportion of 8% and from 14.8 to 34.8% in the strata between 1 and 2 mm. Less than 1% of neurons in the PES area were identified as special cells. Its appearance was an inverted pyramidal cell with a large dendrite extending toward the white matter from which the axon arose.
Perikaryal synthetic function following reversible and irreversible peripheral axon injuries as shown by radioautography
Authors: Engh Charles A. , Schofield Brian H. , Doty Stephen B. , Robinson Robert A. 
Published: December 2004

AbstractRegenerative activity within perikarya of peripheral neurons was studied using light microscopic and standard autoradiographic techniques. Relative incorporation of H3‐leucine into injured neurons was used as an index of their regenerative activity. Reversible and irreversible sciatic nerve injuries were used as the experimental model. Results were correlated with microscopic and functional assessment of progress in nerve regeneration in each animal.Both reversible and irreversible axonal injuries resulted in chromatolysis and initially decreased 30 minute incorporation of the labeled axonal protein precursor into injured cells. A late increase in 30 minute incorporation of the labeled amino acid occurred only in animals subjected to reversible axon injury. In sometimes greater than normal cytoplasmic basophilia and always accompanied demonstrable return of nerve function.These findings are correlated with present concepts of perikaryal synthetic requirements during the various phases of peripheral axon regeneration. It is suggested that the increased synthetic activity within the perikaryon necessary for axon maturation results from the return of a trophic perikaryal stimulus from reinnervated peripheral structures.
A study of normal and congenitally abnormal retinogeniculate projections in cats
Authors: Guillery R. W. , Kaas J. H. 
Published: December 2004

AbstractRetinogeniculate terminations have been studied by fiber degeneration and microelectrode mapping methods in normal cats and in Siamese cats in which the retinogeniculate pathway is congenitally abnormal. The normal representation of the visual field, including the monocular temporal crescent, has been determined. It has also been shown that there is a cellular discontinuity in lamina A which corresponds to the blind spot or optic disc. In normal cats four geniculate layers receive retinogeniculate terminals; two layers (A and C) receive contralateral and two layers (A1 and C1) receive ipsilateral afferents.In Siamese cats laminae A and C are normal. Lamina A1 is broken up into four main cell segments. Two of these receive a normal input from the ipsilateral temporal hemiretina; two receive an abnormal projection from the contralateral temporal hemiretina. The abnormal projection originates primarily from a vertical strip of retina about 20°–25° in width that lies just temporal to the area centralis. Within this abnormal projection a normal retinotopic sequence is maintained but, since this projection goes to the contralateral instead of the ipsilateral lamina A1, the abnormal segments of lamina A1 receive a mirror‐image of the normal representation.Lamina C1 and the medial interlaminar nucleus receive an abnormal contralateral input from the temporal hemiretina similar to that found in lamina A1.