摘要:

AbstractPossible anatomical pathways mediating superior colliculus control of pinna movements were determined in the cat using the orthograde autoradiographic tracing method and the retrograde horseradish peroxidase technique. This was done in the following manner. First, the division of the the pinna muscles with HRP and surveying the facial nucleus for retrogradely filled cells. Second, the brainstem regions that project to the facial neucleus were identified using the horseradish peroxidase method. Third, the superior colliculus projections to these areas were studied using the autoradiographic tracing method.The results suggest that superior colliculus control of pinna movements is mediated entirely by indirect connections with the facial nucleus and that these connections occur mainly in a paralemniscal zone in the lateral midbrain. Of all the brainstem regions shown by the horseradish peroxidase experiments to project to the facial nucleus only this midbrain paralemniscal zone received a projection from the superior colliculus that was dense and overlapped precisely the region containing facial projecting neurons. Further autoradiographic tracing revealed that the facial nucleus was the primary brainstem target of this paralemniscal fibers projecting to the facial nucleus ended in the subdivision that innervates the pinna muscles. Other paralemniscal efferent terminate in the opposite paralemniscal zone. The data suggest that other connections between the superior colliculus and the facial nucleus may occur in the cuneiform nucleus of the midbrain, the region around the oculomotor complex, and the reticular formation dorsal to the superior olive.

ISSN:0092-7317    

DOI:10.1002/cne.901820502

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn Golgi preparations of turtle retina, four types of horizontal cells were observed and their morphological characteristics determined in vertical thick sections, whole mount preparations, and reconstructions from serial 1‐μm sections.H1 consists of a nucleated, stellate cell body (H1CB) and an irregular, tuberous axon terminal (H1AT) connected by a slender axon. Both parts of these cells make contact with receptor cells. H1CB's appear to correspond to “L2‐type cells” while H1AT's correspond to “L1‐type cells” described in the physiological literature.H2 and H3 are axonless stellate cells which are similar to one another in vertical profile and may occasionally appear similar in horizontal view. In general, the dendritic tree is more densely branched and the density of receptor cell contacts is higher for H2 than for H3. H2‐type cells may correspond to “R/G C‐type cells.”H4 is also an axonless stellate cell type which is smaller than H2 or H3 at equivalent retinal locations.The dendritic fields of H1CB's vary widely, but systematically, in size and shape over the retina. Their size is inversely related to receptor cell density, and the shape of the dendritic tree varies from roughly circular in the central area to elliptical in the p

ISSN:0092-7317    

DOI:10.1002/cne.901820503

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

年代:1978

数据来源: WILEY

摘要:

AbstractCriteria were established whereby the chief and accessory members of double cones, red‐, green‐, and blue‐sensitive single cones, and rods could be distringuished form one another in 1‐μm sections through the retinas ofPseudemys scripta elegansandChelydra serpentina. Criteria included the presence or absence of an oil droplet, the size, color, and radial position of the oil droplet, the size and shape of the inner and outer segments, and the shape and orientation of the connection between the perikaryon and synaptic terminal of each receptor cell.Using these criteria, the color‐specific interconnections between horizontal cells and receptor cells were analyzed using 1‐μm serial sections through Golgistained examples of horizontal cells of each type. The results of this analysis area:(a)H1 cell bodies contact both the red‐ and green‐sensitive members of double cones, as well as red‐ green‐sensitive single cones.(b)H1 aoxn terminals contact only the red‐sensitive chief members of doulbe cones, red‐sensitive single cones, and rods.(c)H2‐type cells contact only green‐ and blue senstive single cones.(d)H2‐type cells contact only blue‐sensitive single cones.(e)H2‐type cells contact only green‐sensitive accessory members of double cones.With the exception of H1 cell bodies, all horizontal cells generally contacted every apporpriate receptor cell type within their receptive field. A model for the generation of complex horizontal cell ligh

ISSN:0092-7317    

DOI:10.1002/cne.901820504

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

年代:1978

数据来源: WILEY

摘要:

AbstractVisual and infrared cell layers were identified in the tectum of the pit viperscrotalus viridisandSistrurus melitus. Histologic reconstructions of 48 lesions utilizing the Prussian Blue technique were correlated with micrometer depth readings for 251 visual, infrared and bimodal single unit recordings. The visual cell layer extends caudally from approximately the level of the habenula to the rostral border of the posterior corpora quadrigemina. Neurons responding to visual stimulation are generally contained within zones 7b‐13, i.e., the superficial 600–700 μm of the optic tectum (stratum fibrosum et griseum superficial and the superficial sublayer of stratum griseum centrale). The infrared cell group is found in layer 7 (a and b; stratum griseum centrale) throughout the optic tectum. Eighty percent of the infrared neurons are found within 500–1,200 μm of the surface. In layer 7b the visual and infrared cell groups are mixed; bimodal neurons that respond to a combination of visual and infrared input are located predominantly in this sublamina. The lamination pattern for visual and nonvisual cell groups in the rattlesnake tectum appears to more closely resemble the colubrid tectum and mammalian superior colliculus than the tecta of other r

ISSN:0092-7317    

DOI:10.1002/cne.901820505

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

年代:1978

数据来源: WILEY

摘要:

AbstractSix types of photoreceptors in the red area (dorso‐temporal quadrant) of the pigeon retina are identified using Golgi impregnation, light microscopy and electron microscopy. Golgi impregnation is used to categorize the receptors into morphological types. Examination of oil droplets in the inner segments of cones in fresh, unfixed tissue shows five different types which can be characterized by color, size and stratification. Therefore, in sections through the length of the receptors examined by electron microscopy, the oil droplets contained in the inner segments of the cones can be identified as to their color by their characteristics (i.e., size and stratification), and the groups of receptors thus classified, further characterized as to the morphology of their terminals. Rods have no oil droplets in their inner segments, and their synaptic terminals are located in the outermost stratum of the outer plexiform layer (OPL). Principal members of double cones have yellow oil droplets in their inner segments, while accessory members contain small colorless oil droplets. The synaptic terminals of double cones are located in the same (outermost) stratum of the OPL as rod synaptic terminals. Two types of single, straight cones house either red or orange oil droplets and terminate in the intermediate stratum of the OPL. Oblique single cones with yellow‐green oil droplets in their inner segments contribute synaptic terminals to the innermost stratum of the

ISSN:0092-7317    

DOI:10.1002/cne.901820506

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe ultrastructural basis of presynaptic inhibition of the excitatory efferent axon innervating the opener muscle of the crayfish walking leg was studied using the electron microscope. The inhibitory efferent axon terminals form axoaxonal synapses onto excitor terminals in very close proximity to sites of excitatory transmitter release. There is no evidence that these synapses are located at regions of low safety factor of action potential conduction in the excitor. In the area of axoaxonal synaptic connections, the inhibitory axon also forms inhibitory neuromuscular junctions on the opener muscle. Synaptic vesicles are clustered in active zones bordered postsynaptically by extensive invaginations, or junctional folds, in the sarcolemma. These results are consistent with the hypothesis that the primary effect of presynaptic inhibition is to shunt depolarization‐secretion coupling at specific sites of transmitter release in the target cell, rather than to block impulse propagation into a more generalized population of nerve terminals distal to the axoaxonal synapse. Further physiological implications of this structural arrangement are considere

ISSN:0092-7317    

DOI:10.1002/cne.901820507

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe morphology of neurons in the “hilar region” of the hippocampus (fields CA3cand CA4of Lorente de Nó, '34) was analyzed with several variants of the Golgi technique. Hippocampi were dissected from the brains of 28‐day‐old rats, fixed and impregnated by immersion, and sectioned perpendicular to the long axis. Based on the resident cell types, aspects of the neuropil, and published data related to afferent termination, the area under study was divided into four zones. At least 21 cell types were observed throughout these zones, several of which had not previously been described. Many cells in this area exhibited an impressive number and variety of dendritic and axonal appendages, including spines on the proximal portion of some axons. The close apposition of fibers to these axonal spines suggested the possibility of axo‐axonal interactions. The influence of dentate granule cells, through their mossy fibers, on the synaptic economy of the “hilar region” was found to be more extensive than previously reported. Mossy fibers appeared to terminate on the dendrites of several types of non‐pyramidal cells, which bear no thorny excrescences, by means of thin filiform extensions which emanate from the mossy fiber expansions and by means of thin mossy fiber collaterals which are devoid of typical expansions. Consideration is given to a long‐standing debate as to whether the deep “hilar region” (CA4 of Lorente de Nó, '34, hilus of thefascia dentataof Blackstad, '56) is related more to the hippocampus or to thefascia dentataand it is concluded that the deep hilar region is an area of mergence of thepolymorphic zonesof these twocorticalstructures. The results of the present study do not support the proposition that the deep hilar region is an extension of the pyramidal layer of the hippocampus as suggested by Lorente de Nó ('34), and thus CA4is a misnomer. Rather, the cells in this area are most closely related to the fasciadentataand should thus be considered to lie in the polymorphic zone of “area dentata” as proposed

ISSN:0092-7317    

DOI:10.1002/cne.901820508

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe distribution of sensory cells whose axons traverse the stellate ganglion and project via sympathetic cardiac nerves to the heart of the cat has been examined quantitatively. Horseradish peroxidase (HRP) injected at multiple sites in the right stellate ganglion, or applied to the middle cardiac nerve, labelled small numbers of cells in the thoracic dorsal root ganglia (DRG) from T1to T8. These cells were most numerous between T2and T5and were consistently small (<40 μm) relative to other cells in the DRG. When HRP was applied to middle cardiac nerves, the numbers of labelled sensory cells always exceeded the numbers of myelinated axons counted in the same nerves from other cats. It is concluded that the distribution of the cells of cardiac sensory fibres is more extensive within thoracic DRG than has been previously reported, and it is suggested that such fibres travelling in the sympathetic cardiac nerves may be either myelinated or unmyelinated

ISSN:0092-7317    

DOI:10.1002/cne.901820509

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

年代:1978

数据来源: WILEY

摘要:

AbstractHorseradish peroxidase (HRP) was injected into the optic radiations of adult cats. With placements close to the lateral geniculate nucleus (LGN), the enzyme diffused retrogradely along the axons of geniculocortical relay neurons, entered their cell bodies, and, after reaction with diaminobenzidine, produced a Golgi‐like staining of entire neurons. When the injections were made close to the visual cortex, the enzyme diffused anterogradely and filled complete axonal arborizations in area 17.In the LGN, examples of type 1 and type 2 relay neurons (Guillery, '66) were reconstructed, and their axon diameters measured. The type 1 neurons (thought to correspond to Y‐cells – LeVay and Ferster, '77) possessed large diameter axons (2–3.3 μm), while the type 2 neurons (thought to be X‐cells) had medium‐sized axons (1–1.7 μm). Both types of neurons gave off axon collaterals to the perigeniculate nucleus.In the cortex, two types of afferent supplied layer IV. One distributed to the upper part of the layer (layer IVab), extending a short distance into layer III. The parent trunks of these axons, measured in the white matter, had diameters matching those of type 1 LGN relay cells. The other type distributed to layer IVc. The diameters of these axons matched those of type 2 LGN relay cells. Most afferents of both types gave off collaterals to layer VI — there were no axons which exclusively innervated this layer.The axons supplying layer IVab had a wide lateral spread in the cortex (up to 2 mm), and the boutons were grouped into two to five clumps, whose size and arrangement were similar to ocular dominance columns. The axons supplying layer IVc had a much more restricted arborization, usually consisting of a single clump of boutons.LGN neurons with very fine axons (less than 1 μm) were found in laminae C1–C3. They probably corresponded to Guillery's type 4 neurons. In the cortex, fine‐diameter axons arborized in the upper half of layer I. These axons sometimes had collaterals in the lower part of layer III and in layer V.Taken together, the arborizations of the cortical afferents observed in the present study account fully for the autoradiographic labelling pattern seen after3H‐proline injections into the LGN (LeVay and Gilbert, '76).The identification of type 1 and type 2 neurons as Y‐ and X‐cells is strengthened by the observed difference in their axon diameters, in agreement with the different axonal conduction velocities reported for Y‐ and X‐cells. The presence of cells with very fine axons in the deeper C laminae is consistent with the reported presence of W‐cells (which have slowly conducting axons) in these layers. We conclude that the different classes of geniculate relay neuron have differ

ISSN:0092-7317    

DOI:10.1002/cne.901820510

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

年代:1978

数据来源: WILEY

摘要:

AbstractGroups of pregnant rats were injected with two successive daily doses of3H‐thymidine from gestational day 13 (E13+14) until the day before birth (E21+22). This double labelling procedure was combined with an injection schedule of a single day delay between groups (E13+14; E14+15; E1516.). The two injections assured the comprehensive labelling of practically all neurons of a given structure prior to the onset of their differentiation (comprehensive labelling), whereas the progressive daily delay in injections made it possible to estimate the proportion of neurons formed in various regions of the hypothalamus on a single day. Hypothalamic areas or nuclei were assigned into four classes on the basis of their cytogenetic isochronicity. Structures composed of the earliest arising (class 1) neurons constitute a lateral tier that includes the lateral preoptic and lateral hypothalamic areas, and the lateral mammillary nucleus. Structures composed of early arising (class 2) neurons form a heterogeneous collection of nuclear systems, including the Para ventricular, intern clear and supraoptic magnocellular neurons, and several intermediate tier nuclei of the anterior and posterior hypothalamus. The late arising (class 3) and latest arising (class 4) nuclei constitute a periventricular system anteriorly and a more extensive region posteriorly. The latter two nuclear systems may constitute the hypophysiotropic area of the hypothalamus. The nuclei of the mammillary system, which are produced sequentially, are distinguished from other hypothalamic structures by their more rapid generation time. Internuclear labelling gradients were used to infer the neuroepithelial site of origin and setting pattern of neurons. common sites of origin were indicated for the following structures: the magnocellular neurohypophysial neurons; the neurons of the dorsomedial and ventromedial nuclei; and the neurons of the tuberomammillary and arcuate nuclei. The sites of origin of these groups of nuclei were related to specialized ventricular linings in the mature hypothalamu

ISSN:0092-7317    

DOI:10.1002/cne.901820511

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

年代:1978

数据来源: WILEY