摘要:

AbstractThese experiments were designed to study the projections to the pons from visual and visual association cortex of monkeys by degeneration staining and horseradisch peroxidase (HRP) methods. When lesions were made in these cortical visual areas, degenerated fibers were found in the rostral dorsolateral area of the pontine nuclei. When HRP was injected among visually responsive cells in this region of the pons, layer V cortical pyramidal cells were labeled. These labeled cells were concentrated most heavily on both banks of the superior temporal and intraparietal fissures, and on the rostral bank of the parieto‐occipital fissure. The efferent targets and receptive field properties of these cortical regions are consistent with their possible role in visual guidance of movemen

ISSN:0092-7317    

DOI:10.1002/cne.901900202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe projections of the lateral part of the deep mesencephalic nucleus (DMN) were traced by autoradiography and retrograde horseradish peroxidase (HRP) techniques. At the level of the DMN, projections from its lateral part crossed the midline and terminated in the medial and lateral part of the contralateral DMN. Furthermore, two labeled tracts passed rostrally from the lateral part of the DMN. One tract coursed dorsolaterally from the lateral DMN to terminate in the ipsilateral lateral thalamic nucleus. The second tract coursed ventrally and rostrally over the substantia nigra toward the ipsilateral zona incerta. At the caudal part of the zona incerta these fibers divided into two bundles. One bundle coursed superiorly to terminate bilaterally in the mediodorsal nucleus of the thalamus. The second bundle of fibers passed anteriorly to enter the ipsilateral zona incerta. Some of these fibers terminated upon neurons of the zona incerta and the ventromedial part of the subthalamic nucleus. The remaining fibers within the zona incerta coursed anteriorly to enter the internal capsule. These fibers terminated in the entopeduncular nucleus and medial part of the globus pallidus. These findings indicate that the lateral part of the DMN is likely to be involved in the ascending activating system of the reticular formation by connections with thalamic nuclei. Furthermore, the lateral part of the DMN may play a part in suprasegmental motor control via connections with rostral brain stem motor centers.

ISSN:0092-7317    

DOI:10.1002/cne.901900203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe projections of the medial part of the deep mesencephalic nucleus (DMN) were traced by autoradiography and retrograde horseradish peroxidase (HRP) techniques. No ascending projections were observed from the medial part of the DMN; however, two groups of descending fibers were observed. One group crossed the midline and coursed to the caudal part of the red nucleus. At this point, these fibers divided into two distinct bundles. One bundle of fibers passed caudally to terminate in the contralateral pontine reticular nucleus, superior olive‐trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. The other bundle entered the medial longitudinal fasciculus (MLF) and coursed through the pons and medulla without termination, to enter the cervical spinal cord where terminations were noted in the dorsal horn. The other group of fibers from the medial DMN descended through the ipsilateral pons and medulla, projecting to the pontine reticular nucleus, superior olive‐trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. These findings indicate that the medial part of the DMN is likely to be involved in complex sensorimotor events via reticulobulbar and reticulospinal connecti

ISSN:0092-7317    

DOI:10.1002/cne.901900204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe projections of the nucleus of the solitary tract (NST) were studied by autoradiographic anterograde fiber‐tracing and horseradish peroxidase (HRP) retrograde cell‐labeling. Tritiated proline and leucine were deposited in electrophysiologically identified regions of NST. Injections of NST at levels caudal to where the vagus enters the nucleus, from which responses were evoked by stimulation of cranial nerves IX and X, revealed topographically organized bilateral projections to, most prominently, the ventrolateral medullary reticular formation which contains neurons of the ambiguus complex, and to the lateral and medial parabrachial nuclei, including a small portion of the medially adjacent central gray substance. Labeled fibers in the ventrolateral reticular formation were present from the nucleus retroambigualis rostralward to the retrofacial nucleus, with the densest concentration located over the nucleus ambiguus proper. The parabrachial projection was confirmed using HRP and shown to originiate from cells in the medial subdivision of NST. Due to the problem of fibers en passant, it was not possible to interpret conclusively the cell‐labeling seen around the solitary tract after HRP injections made in the region of the nucleus ambiguus. Labeled fibers were also traced from caudal NST to the dorsal motor nucleus of the vagus, but their origin could not be determined with certainty. Other labeled axons, traced to circumscribed parts of the inferior olivary complex and via the contralateral medial lemniscus to VPL of the thalamus, were shown in HRP experiments to originate from the dorsal column nuclei rather than NST. No labeled fibers were traced into the spinal cord, nor were any cells labeled in NST after large HRP deposits in upper cervical segments.Isotope deposits at levels of NST rostral to the entrance of the vagus, from which responses were evoked by rapid stimulation of the tongue, revealed an ipsilateral projection which ascends as a component of the central tegmental tract to the parvicellular part of the ventral posteromedial thalamic nucleus (VPMpc). After small HRP deposits in VPMpc, labeled cells in NST were restricted to the rostral part of the lateral subdivision. No labeled axons were traced from rostral NST to the ambiguus complex or parabrachial area. Injections of3H‐amino acids at intermediate levels of NST resulted in fiber‐labeling in VPMpc, the parabrachial area, and the ambiguu

ISSN:0092-7317    

DOI:10.1002/cne.901900205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe number of neurons and their distribution were determined for specific segmental ganglia from the nerve cord of four different species of leech. Quantitative data were obtained by using computer‐aided techniques for the analysis of nerve structure from serially sectioned or whole‐mounted tissue. The species studied wereHirudo medicinalis, Macrobdella decora, Haemopis marmorata(family Hirudinidae), andHaementeria ghilianii(family Glossophoniidae).Two sets of ganglia were studied in each species: middle ganglia (9, 10, and 11) and sex ganglia (5 and 6). The middle ganglia, as well as the rest of the 21 segmental ganglia, except 5 and 6, are thought to be quite similar. The sex ganglia are associated with the sexual organs and appear to have more neurons.The data reported here indicate that: a) the number of neurons in a specified ganglion varies by one to two percent from animal to animal of a given species; b) the middle ganglia of a particular leech each have approximately the same number of neurons, with a variation also within two percent; c) the middle ganglia ofHirudo, Macrobdella, andHaementeriahave some 20 fewer (about 380); d) the sex ganglia ofHirudo, Macrobdella, andHaemopishave a few hundred more neurons than their middle ganglia, with the exact number varying according to the species, but the sex ganglia inHaementeriahave only about 20 more neurons than their middle ganglia; e) the distribution of neuronal somata among glial packets is not symmetric about the midsaggital plane of the animal, and the number of somata in each packet is variable; and f) the geometry of the glial packets is generally invariant, but occasionally packets are found in abnormal positi

ISSN:0092-7317    

DOI:10.1002/cne.901900206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractPaired specimens of the neostriatum were taken from monkeys at zero (newborn), one, two, four, eight, and 16 weeks of age, and prepared for Golgi impregnations and electron microscopy. Light microscopy shows that in the first postnatal week, the structure contains the five neuronal types and four categories of afferent axons described in the adult, as well as some cells too undifferentiated to classify. Most neurons exhibit immature dendritic features, including local enlargements, terminal growth cones with filopodia, and filiform processes. Inspiny type Icells, various levels of maturity may coexist in regions of a single dendrite, in different dendrites of the same neuron, and among individual cells. Spine density increases progressively with age, but the relative distribution of spine types remains about the same.Spiny type IIneurons show some decline in spine density, and generally mature sooner than spiny type I cells. The long axons of spiny neurons have varicosities which disappear at about eight weeks. In younger animals (newborn and one week), the dendrites of aspiny neurons (types I, II, and III) may have a “spiny” appearance, exhibiting many spine‐like and filiform processes. Concurrently, the short axons vary in degree of arborization from very immature to well developed.Electron microscopy corroborates the developmental features recognized in the Golgi material: dendritic and axonal growth cones, filopodia and varicosities, as well as various stages of maturation in somata and dendrites. Degenerating elements, mostly of an axonal nature, are seen up to eight weeks. The synapses which reach maturity at birth are of the asymmetric axospinous type, in which the axonal profile contains small round vesicles, and of the symmetric axodendritic class, with the presynaptic elements having pleomorphic vesicles. Some synapses are slower to mature and appear at one to eight postnatal weeks. These include those made by profiles with pleomorphic vesicles, forming either symmetric contacts with somata and axon initial segments, or asymmetric contacts with spines. The same applies to the asymmetric axodendritic synapses made by elements containing small round vesicles. Finally, profiles containing large round or flat vesicles are the latest to participate in mature synapses formation.Findings indicate that a considerable degree of qualitative and quantitative change takes place in the monkey neostriatal neuropil during early postnatal development, especially in the first eight‐week

ISSN:0092-7317    

DOI:10.1002/cne.901900207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe projections of cat retinal ganglion cells to the superior colliculus (SC) were examined using the method of retrograde axonal transport of horseradish peroxidase (HRP). Several injections of HRP were made in a single SC after the visual projection to the injection sites had been established physiologically. The HRP injections resulted in a homogeneous distribution of labelled ganglion cells in whole mount preparations of the retinae of both eyes. In the eye contralateral to the injected colliculus, ganglion cells with a crossed projection were labelled in both nasal and temporal retina; in the ipsilateral eye, ganglion cells with uncrossed projection were labelled only in the temporal retina. Analysis of the counterstained retinal whole mounts indicated that at least 50% of all ganglion cells in the nasal retina and 26% in the temporal retina have a crossed projection to SC, and that 24% of all ganglion cells of the temporal retina have an uncrossed projection to the SC.The morphological classes of retinal ganglion cells have different patterns of crossed/uncrossed decussation and they participate in varying proportions in the retino‐tectal projection. Almost all Alpha cells in the retina send axon collaterals to the SC. Probably only about 10% of the Beta cells project to the SC and at least 80% of all Gamma cells send axons to the S

ISSN:0092-7317    

DOI:10.1002/cne.901900208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe folial pattern of the mouse cerebellum was compared in 13 inbred strains and a closed colony. The morphological variation of the cerebellum among individual animals was slight within each inbred strain, whereas it was marked in the closed colony. There was no sex‐related difference in the cerebellar folial pattern. The cerebellum of mice from each inbred strain presented a characteristic folial pattern in which some similarties were recognized among animals from genetically related strains. These findings revealed that the morphological variation in the folial pattern of the cerebellum was strain‐specific in mice and had an intimate connection with the genetic cont

ISSN:0092-7317    

DOI:10.1002/cne.901900209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe hindbrain and spinal cord were studied by transmission electron microscopy with and without lanthanum nitrate treatment in nine‐day embryos of the loop‐tail (Lp) mutant mouse. Homozygous (Lp/Lp) individuals exhibit dysraphism from the hindbrain caudally throughout the embryo; in +/+ andLp/+ individuals, the brains and spinal cords are normal. In contrast, the ventricular cells in the abnormal hindbrain and spinal cord showed increased amounts of intericellular space in an area intermediate between the luminal border and basal zone, and a flattening which occurs variably in their luminal surfaces. A most striking difference occurred in the frequency of gap junctional vesicles, circular structures bounded by a double membrane and containing ribosome‐like material. A quantitative analysis of the distribution of these organelles revealed that they are more numerous in the dysraphic hindbrain and lumbosacral spinal cord of the abnormal animals than in comparable regions of the normal; however, in the cervicothoracic spinal cord, the frequency of these vesicles is similar. In specimens treated with lanthanum, the tracer freely penetrated the luminal junctional complexes in both normal and abnormal animals, but was not present between the membranes of the gap junctional vesicles. The developmental significance of gap junctional vesicles frequently located in juxtaluminal regions of mitotic cells, but also found deeply in dividing cells, is not known; they may relate to cell‐to‐cell attachment and/or communication. In any event, furthe study of them may prove valuable in understanding normal and abnormal development of the ne

ISSN:0092-7317    

DOI:10.1002/cne.901900210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe location of central neurons that contribute preganglionic parasympathetic axons to cranial nerves VII, IX, and X in rats has been identified using horseradish peroxidase (HRP) tracting methods. Collectively, these neurons form an uniterrupted dorsal column that extends over the entire length of the medulla. The cephalic end of this column turns ventrally with neurons scattered in the parvicellular reticular formation between the rotral pole of the nucleus of the solitary tract (NST) and the facial motor nucleus. Applying HRP crystals to the cut cervical vagus labels neurons in the classically defined dorsal motor nucleus. Rostrally, this distribution continues along the medial edge of NST, ending just caudal to neurons exiting in the lingual‐tonsilar branch of IX. At the rostral pole of the NST and ventral to it, neurons occur that serve the lingual‐tonsilar and tympanic branches of IX, as well as the chorda tympani and greater superficial petrosal (GSP) branches of VII. Central neurons of the chorda tympani and tympanic nerves spread ventrally from NST into a sparse but largely coextensive distribution in the reticular formation lateral to the ascending radiations of the facial motor nucleus. Immediately ventral to this distribution, a dense accumulation of GSP efferent neurons appears rostrolateral to the facial motor nucleus. Although they vary considerably in number and packing density, the neurons of the dorsal efferent column and those extending from it into the reticular formation have similar morphological characteristics. The somata are medium‐sized, fusiform, or multipolar, but with usually no more than five or six major proc

ISSN:0092-7317    

DOI:10.1002/cne.901900211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY