bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microanatomy of the ganglionic roots of the abdominal cord of the crayfish, Orconectes virilis (hagen)
Authors: Somers Michael E. , Nunnemacher Rudolph F. 
Published: December 2004

AbstractLow magnification electron micrographs were used to construct montage maps of cross sections of the three roots of the second abdominal ganglion of the crayfish Orconectes virilis. Arbitrary fiber diameter size ranges were established within the total size range of 0.2 μ to 55 μ. Fibers within each of the ranges were counted and their positions noted. The first root contains 2,451 fibers and is divided internally into distinct anterior and posterior halves. The posterior half contains 98.2% of the roots total number of fibers below 1 μ in diameter and these are contained primarily in 13 bundles. The second root is divided internally into five subregions and contains a total of 2,741 fibers. The size distribution of the fibers within each of the subregions is noted and compared with the fiber size distribution of the peripheral branches. The subregions are assigned functions based on their similarity to root branches of known activity. The third root contains two distinct elements, a phasic branch containing 13 fibers ranging from 6 μ to 55 μ and a tonic branch containing six fibers ranging from 3.5 μ to 21 μ.
The laminar distribution of retinal fibers in the dorsal lateral geniculate nucleus of the cat: A new interpretation
Authors: Guillery R. W. 
Published: December 2004

AbstractThe cell laminae of the lateral geniculate nucleus have been studied in relation to the retinogeniculate degeneration shown by the Nauta method. In agreement with previous accounts laminae A and A1 have been shown to receive contralateral and homolateral inputs respectively. However, ventral to lamina A1 three laminae have been defined. Lamina “C” contains large cells and receives coarse contralateral fibers, lamina “C1” contains smaller cells and receives fine homolateral fibers, while lamina “C2,” which consists of small cells next to the optic tract contains many fibers passing through to other laminae but shows no particular concentration of pericellular degeneration.The precise relationship between fiber degeneration and cytoarchitectonic borders can be seen only in Nauta sections that have been counterstained by a Nissl method. Such material provides no evidence of any zone where homolateral and contralateral fibers overlap. Between laminae A and A1, and A1 and C there are narrow, relatively cell free zones, which, in many parts of the nucleus, receive no significant retinogeniculate input.The fiber degeneration appears earliest in the peripheral parts of laminea A and A1, the homolateral degeneration slightly preceding the contralateral degeneration on the third day. The degeneration in the central parts of these laminae appears about 24 hours later and is never as dense. The fine fibers in lamina C1 do not show degeneration clearly until the sixth day.
Morphology and cytoarchitecture of the red nucleus of the domestic pig (sus scrofa)
Authors: Otabe Jack S. , Horowitz Aaron 
Published: December 2004

AbstractThe morphology and cytoarchitecture of the red nucleus was studied in 17 pigs of different ages and breeding. Transverse, sagittal and horizontal sections were stained by cresyl violet, Weil's method and the Klüver and Barrera method. The length of the red nucleus of the pig was about 6.09 mm and the width was 2.66 mm on horizontal section, while the height of the nucleus was approximately 2.87 mm on both transverse and sagittal sections.Parvocellular and magnocellular parts were readily identified on horizontal section. The former occupied the three‐fifths rostral portion of the nucleus, and the latter occupied the two‐fifths caudal portion. There was a clear division between the two parts.Five subdivisions within the nucleus were identified: N. ventrolateralis parvocellularis, N. dorsomedialis parvocellularis, N. ventromedialis magnocellularis, N. dorsolateralis magnocellularis and N. cornualis lateralis. Large, medium, and small neurons were identified. The large neurons were over 50 μ in diameter; the medium had a range between 26 μ and 49 μ and the small ones were under 25 μ. No nucleus minimus was identified. The red nucleus of the pig did not lie parallel to the midline. The longitudinal axes of right and left nuclei met caudad at 60°. The magnocellular part consisted of about 65% large, 28% medium and 7% small neurons. The ratio of the large, medium and small neurons of the whole nucleus was 4:5:2.
An experimental analysis of the determination of cell patterns in the spinal cord of the chick embryo
Authors: Narayanan C. H. 
Published: December 2004

AbstractThe effects of rotation of the brachial region of the spinal cord about its longitudinal axis between stages 12 to 15 were studied in a series of 30 chick embryos by transplanting that portion of the neural tube opposite somite levels 16 to 20 from a donor embryo to a host embryo at the same stage of development. Despite the altered topographical relationship between the transplanted neural tube and the adjacent mesodermal somites, the cytological characteristics of the cells and the organization of the major cell groups derived from the alar and basal halves of the cord remained unaffected. In the more successful experiments, well‐developed lateral motor columns and ventral roots and dorsal roots and spinal ganglia could be identified in the usual morphological relationships even though the graft piece of spinal cord was clearly inverted compared to the remaining part of the spinal cord of the host embryo. A limited number of cell counts of the lateral motor column in some of these cases showed no significant difference in cell number, nor was there an appreciable change in the general morphology of the cell groups in the transplanted cord compared to the lateral motor columns of control embryos at similar developmental stages.
Rubrobulbar projections of the opossum (didelphis virginiana)
Authors: Martin George F. , Dom Richard 
Published: December 2004

AbstractThe course and distribution of rubral pathways to the pons and medulla were determined for the opossum by employing the Nauta‐Gygax and Fink‐Heimer techniques on the brain stems of animals with lesions either within the red nucleus or involving the fibers emanating from it. Control material was provided by previous studies on corticomesencephalic and tectal efferent pathways and by the brains of specimens subjected to deep midbrain lesion which did not involve the red nucleus.A predominantly crossed rubrobulbar pathway coursed through the brain stem as described by Voris and Hoerr ('32) and distributed to the nucleus “K” of Meessen and Olszewski ('49), to neurons interspersed between the fiber bundles of the motor root of the trigeminal nerve, to the parabrachial nucleus of the brachium conjunctivum, the parvocellular reticular formation, the ventral and medial portions of the spinal trigeminal nucleus (nucleus oralis and interpolaris), the lateral and intermediate portions of the motor nucleus of the facial nerve, the lateral reticular nucleus, the ventral external arcuate nucleus and the subnucleus reticularis dorsalis medullae oblongatae. The possible significance of these connections in the opossum is discussed.
Trigeminal proprioceptive projections to the hypoglossal nucleus and the cervical ventral gray column
Authors: Mizuno Noboru , Sauerland Eberhardt K. 
Published: December 2004

AbstractTrigeminal proprioceptive projections to the hypoglossal nucleus and the cervical ventral gray column in the cat were investigated by means of neuroanatomical and neurophysiological methods. Degeneration studies (Nauta and Fink‐Heimer methods) involved circumscribed electrolytic lesions of the trigeminal mesencephalic nucleus and/or the supratrigeminal nucleus. Degenerated fibers in Probst's tract, which is composed of the central processes of trigeminal mesencephalic neurons, terminated in the ventrolateral portion of the ipsilateral hypoglossal nucleus and in the medial part of the ventral gray column of C1–C4. The descending juxtatrigeminal fascicle, a separate bundle of degenerated fibers, originated from the supratrigeminal region, which is known to receive processes from trigeminal mesencephalic neurons. This descending fascicle contributed fibers to the spinal trigeminal nucleus and the juxtatrigeminal reticular formation, from which region interneurons connect to the hypoglossal nucleus. Probst's tract, as well as the descending juxtatrigeminal fascicle, could be considered as parts of two separate polysynaptic pathways from trigeminal proprioceptors to those motoneurons responsible for the innervation of the tongue and infrahyoid musculature. Electrophysiological experiments revealed that proprioceptive muscle afferents from the masseter muscle project directly to the ipsilateral hypoglossal nucleus and to the ipsilateral upper cervical ventral column.
Cell proliferation, migration and differentiation in the cerebral cortex of the golden hamster
Authors: Shimada Morimi , Langman Jan 
Published: December 2004

AbstractThis work was undertaken: (1) to determine the sites of cell proliferation in the cerebral cortex of the hamster during prenatal life and shortly after birth; (2) to study the migration pattern of neuroblasts before and shortly after birth; and (3) to examine the differentiation of the neuroblasts during migration and after arrival at their final location.Tritiated thymidine was injected in pregnant hamsters at various days of gestation and in newborn animals. When one hour after treatment the parietal cortex of the embryos was examined for DNA synthesis, labeled cells were found in the neuroepithelial layer but not in the cortical layers. In the newborn radioactive cells were found both in the neuroepithelial layer and in the subependymal layer, a layer consisting of polymorph cells and developing at the end of prenatal life. Hence during embryonic life cell proliferation in the parietal cortex is restricted to the neuroepithelial layer, but in the newborn the subependymal layer is also ctive in cell production.When the generation time of the neuroepithelium was determined, the DNA synthetic phase was found to be six hours, the pre‐duplication and prophase about one and one‐half hours and the post‐duplication stage about four and one‐half hours. Hence the duration of the generation time of the neuroepithelial cells during embryonic life is about 12 hours.To examine the migration pattern of the neurons formed during embryonic and postnatal life, pregnant hamsters were injected at successive days of gestation and the embryos sacrificed at the twentieth postnatal day. A similar procedure was followed for newborn animals. It was thus found that neuroblasts formed during the early stages of development occupy the deep layers of the cortex, while those formed during the later stages of intrauterine life and during the first postnatal days occupy the more superficial layers. Hence, neuroblasts produced during the final stages of development migrate through the cell layers formed at previous days to reach the surface of the cortex. The time required for this migration varied in the newborn hamster from three to five days.When newborn hamsters were injected with tritiated thymidine and the labeled cells traced during the following ten days, it was noted that the cells released by the neuroepithelial layer arrived in the deeper layer of the cortex about 48 hours after labeling. The cells were characterized by a spindle‐shaped nucleus while the cytoplasm was seen to extend in peripheral direction. Shortly after arrival at the surface of the cortex the cells lost their spindle shape and the nucleus became oval‐shaped with a pale nucleoplasm. Subsequently the cells were characterized by a small round pale nucleus with two or three nucleoli close to the nuclear membrane. Approximately nine days after treatment the labeled cells were clearly recognizable as advanced neuroblasts with a large, pale nucleus and one or two nucleoli.
Cervicothalamic tract in the dog
Authors: Hagg Sigrid , Ha Hongchien 
Published: December 2004

AbstractThe spino‐cervico‐thalamic pathway in the dog was studied by means of the Marchi method. The pathway which takes its origin from the nucleus cervicalis lateralis (NCL) at the first two cervical segments of the spinal cord was demonstrated following restricted lesion in the dorsal quadrant involving the nucleus. The axon of neurons of NCL form a prominent bundle which crosses exclusively to the contralateral ventral funiculus via ventral white commissure. At first, the fiber bundle occupies a medial position and gradually shifts laterally as ascending. In the lower portion of the medulla oblongata the fiber bundle is closely attached to the lateral pole of the inferior olivary nucleus and gives collaterals to it. The pathway maintains its lateral position to the medial lemniscus throughout the brain stem and terminates in the nucleus ventralis posterolateralis of the thalamus occupying mainly its ventrolateral border.The topographic relation between cervicothalamic and classical spinothalamic pathways are discussed.
Relationships between glial and neuronal elements in the development of long term cultures of the spinal cord of the fetal mouse
Authors: Guillery R. W. , Sobkowicz Hanna M. , Scott G. L. 
Published: December 2004

AbstractThe development of glial and synaptic relations has been studied in long term cultures of spinal cord by light and electron microscopy.During the first three days in vitro there is extensive cell death in the superficial parts of the explants, where one sees many phagocytes and much cellular debris. The ependyma of the explants early forms a closed sac in the deep parts of the culture next to the collagen substrate. Cells migrate from this sac to form a continuous basal layer upon the substrate. Some of these cells turn around the edges of the explant and migrate onto its surface, where they contribute to an ependyma‐like epithelial covering. As the explants mature most of the cellular debris is cleared; the epithelial covering separates the neuronal elements from the feeding solution and from phagocytes, most of which migrate to lie freely on the surface of the epithelium.Two types of outgrowth are formed. The first consists of bundles of nerve fibers which are accompanied by individual undifferentiated glial cells. The second forms as a broad sheet of undifferentiated glial cells and astrocytes and this is continuous, at the edge of the explant, with the glia of the basal layer. Nerve fibers that grow into this sheet appear to survive better than nerve fibers that grow out in bundles. Oligodendroglial cells become recognizable by electron microscopical criteria when the axons start to myelinate.Dendrites can be identified in the sheet‐like outgrowth but not in the bundles. Synapses are seen only where dendrites are identifiable. Serial axo‐axonal junctions have not been found and axosomatic synapses are relatively rare.
Visual intensity and pattern discrimination deficits after lesions of ectostriatum in pigeons
Authors: Hodos William , Karten Harvey J. 
Published: December 2004

AbstractEighteen pigeons were trained to discriminate between visual stimuli that differed in either intensity or pattern. Bilateral, electrolytic lesions were made in ectostriatum or the lateral neostriatum. Pigeons with ectostriatum lesions had severe post‐operative performance deficits. The magnitude of the deficit and the amount of post‐operative retraining necessary to restore the birds to pre‐operative performance levels varied directly with the amount of bilateral destruction of ectostriatum. Pigeons with little or no involvement of ectostriatum showed little or no change in discrimination performance post‐operatively. Similarities between morphological and functional organization of the reptilian, avian and mammalian visual systems are discussed.
On the inferior olive of the albino rat
Authors: Schild Renée F. 
Published: December 2004

AbstractThe average of neuron counts made in five rat inferior olives was 24,400 neurons per olive, i.e., 48,800 per rat, — 6.8 times fewer than the number of rat cerebellar Purkinje cells. The medial accessory olive was larger, both in terms of volume and cell numbers, than either the dorsal accessory or principal olives. The overall packing density, determined in one olive, was 43,900 neurons/mm3, but there were local fluctuations within the olive. In particular, packing density was somewhat higher at the rostral end of the medial accessory olive.
Medullary cells of origin of vagal cardioinhibitory fibers in the pigeon. II. Electrical stimulation of the dorsal motor nucleus
Authors: Cohen David H. , Schnall Adrian M. 
Published: December 2004

AbstractStimulation of the peripheral end of the cervical vagus results in marked bradycardia, a secondary fall in blood pressure, and little change in respiration. Stimulation of the central end results in immediate apnea, a moderate fall in blood pressure, and little change in heart rate.Electrical stimulation of the dorsal medulla produces short‐latency bradycardia at points clustering in: (a) lateral dorsal motor nucleus, 0.5–1.0 mm rostral to the obex; (b) solitary tract; and (c) commissural nucleus of Cajal. Apnea frequently accompanies bradycardia except when elicited by stimulation of the dorsal motor nucleus. Hypotension always follows bradycardia, while hypertension accompanies tachycardia. These bradycardia responses are abolished by bilateral vagotomy and severly diminished when the ipsilateral vagus is cut or pharmacologically blocked. Beta‐sympathetic blockade has no effect on the occurrence of bradycardia responses.It is concluded that an efferent cardioinhibitory region in the pigeon is localized in the lateral dorsal motor nucleus 0.5–1.0 mm rostral to the obex and that bradycardia elicited from the solitary tract and commissural nucleus result from stimulating afferents. These results correlate nicely with the localization of the cells of origin of vagal cardioinhibitory fibers based on retrograde degeneration experiments, and together the anatomical and physiological findings indicate a concentration of these neurons in the ventrolateral aspect of the dorsal motor nucleus approximately three‐quarters of a millimeter rostral to the obex.
Increase in number of synapses in the inner plexiform layer of light deprived rat retinae: Quantitative electron microscopy
Authors: Sosula Leo , Glow Peter H. 
Published: December 2004

AbstractOne eye in each of five adult Wistar hooded rats was covered with opaque contact occluders for three or nine months. The rat retinae were studied with light and electron microscopy. No changes in retinal thickness or in gross structure were seen. However, quantitative differences in synaptic organisation were found.(1) First comparison. A montage of a normal retina was compared with a similar montage of a three month lighted‐deprived retina. Taking equal areas of inner plexiform layer, the number of amacrine (conventional) synapses in the light‐deprived montage was larger by a factor of about 2.4 relative to the normal one. No significant difference in the number of bipolar (ribbon) synapses was found.(2) Second comparison. Samples were compared from five normal and five light‐deprived retinae. The light‐deprived retinae showed a significantly larger number of amacrine synapses compared with the normal mean (p<0.02).It was not possible to determine if the changes in synaptic number are related to changes in vesicle dimensions reported herein.The increased number of conventional synapses seems evidence that central nervous tissue is capable of forming new synapses without changing the organisation of neural processes.
Reticulospinal fibers of the opsossum, Didelphis virginiana. II. Course, caudal extent and distribution
Authors: Martin George F. , Dom Richard 
Published: December 2004

AbstractLesions were placed in the deep midbrain tegmentum and within areas of the pontine and medullary reticular formation which were determined by the retrograde degeneration method to give rise to reticulospinal fibers. The location of each lesion was verified histologically and the spinal cords processed by either the Nauta or Fink‐Heimer method. Control material for the origin of degenerated fibers was provided by previous studies on corticospinal, tectospinal and rubrospinal fibers in the same form.Fibers degenerating as a result of mesencephalic tegmental lesions followed the ipsilateral ventral funiculus and could be traced as far caudal as midthoracic levels. They ended in Rexed's laminae VII and VIII.Lesions of the pontine reticular formation resulted in the degeneration of fibers within the ventral funiculus of the spinal cord. The great majority of these fibers followed an ipsilateral course. Such pontospinal fibers were present throughout the length of the spinal cord; their terminal distribution appears to take place mainly within laminae VII and VIII. At certain levels, however, such fibers could be traced into lamina IX.Lesions in the medial medullary reticular formation resulted in fiber degeneration chiefly within the ipsilateral ventral and lateral funiculi. However, a few fibers were present on the side opposite the ablation. This fiber system extends throughout the length of the spinal cord and distributes itself in laminae VII and VIII and, at certain levels, also in lamina IX. Lesions isolated to the lateral, parvocellular portion of the medullary reticular formation resulted in fiber degeneration located within the propriospinal bundles of the lateral funiculus which could be traced to rostral cervical levels. Such lesions also interrupted the rubrospinal tract in the its medullary trajectory.