摘要:

AbstractImmunocytochemical methods were used for selective labeling and characterization of amacrine cells of the turtle (Pseudemys scripta elegans) retina which contained neuropeptide‐like immunoreactivity (leu‐enkephalin, glucagon, and neurotensin). Processes of amacrine cells arborized in specific strata of the inner plexiform layer (IPL). Different strata were defined in relation to the boundaries of the IPL. Zero represented the strata nearest the inner nuclear layer and 100 represented the strata nearest the ganglion cells.Antisera directed against leu‐enkephalin labeled approximately 7,300 amacrine cells in a single turtle retina which were concentrated in the region of the visual streak and decreased in density toward the periphery. In retinal regions outside the visual streak the labeled neurons were similar in size and shape with dendritic arbors which lacked a particular orientation. In contrast, in the visual streak, there were particular neurons which were labeled with enkephalin antiserum which had elongated dendritic arbors that ran parallel to the streak. Both types of amacrine cells with enkephalinergic immunoreactivity sent their dendrites into the 0–20 region and the 65–100 region of the IPL.Antisera directed against glucagon labeled approximately 2,500 amacrine cells in a single turtle retina. These cells were concentrated in areas near the visual streak. Amacrine cells labeled with glucagon antiserum had dendritic arbors which were asymmetrically skewed toward one end of the cell and ramified in the 0–20 strata with sparse projections at the 40 and 80 strata of the IPL.Antisera directed against neurotensin labeled 12,800 amacrine cells in a single turtle retina These cells were concentrated in the region of the visual streak. Two distinct amacrine cell types were labeled selectively. One type had a large, vertically oriented cell body (10 × 14 μm) which gave rise to a single 2‐μm‐thick process that branched and ramified within the 45–70 strata. The other amacrine cell type with neurotensin‐like immunoreactivity had a smaller cell body (8 μm) that sent numerous thin dendrites into the same 45–70 strata.The present results indicated that various neuropeptides were present in amacrine cells of the turtle retina and that a specific neuropeptide could be found in more than one anatomical type of amacrine cell. Each anatomical type of amacrine cell had a unique dendritic arborization which ramified within particu

ISSN:0092-7317    

DOI:10.1002/cne.902210402

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

年代:1983

数据来源: WILEY

摘要:

AbstractRats received a midthoracic spinal cord “overhemisection” including right hemicord and left dorsal funiculus at birth (neonatal operates, N = 15) or 21 days of age (weanling operates, N = 14). In a second experiment neonatal (N = 6), 6‐day (N = 3), and 12‐day (N = 7) rats sustained a right sensorimotor cortex (SmI) ablation to destroy the left corticospinal tract (CST) at the same time as the spinal injury (double lesion operates). Later (3–12 months) injections of3H‐proline and autoradiography were used to label the left or right CST. The results of the first experiment showed that most right CST axons failed to grow around the spinal lesion in neonatal operates (N = 9). There was an increase in the density of label, mainly to CST projection areas, in a 1‐mm zone rostral to the lesion. However, left CST axons bypassed the lesion by growing through the intact tissue in neonatal operates (N = 6). These displaced axons were consistently located within the dorsal portion of the lateral funiculus (dLF) and remained within that location caudal to the lesion, an area normally containing only a few CST axons. In spite of this abnormal position, these axons terminated bilaterally throughout the remainder of the cord in normal CST sites. In weanling operates, CST axons severed by the lesion did not regenerate around the lesion site. An increased density of label over the few spared axons within the left dLF and in CST projection zones immediately caudal to the lesion site suggested axonal sprouting by these axons. The results of the second experiment showed that the lack of growth of right CST axons around this injury in neonatal operates was, at least partially, due to an interaction with left CST axons. In neonatal double lesion operates, right CST axons grew around the spinal injury for a varying distance within the left dLF and distributed bilaterally to normal CST sites. The number of right CST axons bypassing the lesion was related to the configuration of the lesion site. A smaller number of right CST axons bypassed the lesion in 6‐day double lesion operates and most terminated within 2–3 mm of the lesion site. Right CST axons failed to grow around this injury in 12‐day double lesion operates. We conclude that the availability of intact spinal cord tissue allows uncut developing left CST axons to grow around a lesion when their primary pathway is destroyed. Differences in growth of left and right CST axons appear to be related to an interaction between left and right CST axons which limits the growth of right CST axons across the midline. The ability for CST axons to grow around this injury decreases at the time these axons are elongating through this region and ceases at the time synapses are being formed by these axons. However, further experiments are necessary to determine if these factors in the maturation of the CST, of if other factor in the maturation of the spinal cord, are critical in limiting CST groth after spinal injuryin

ISSN:0092-7317    

DOI:10.1002/cne.902210403

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

年代:1983

数据来源: WILEY

摘要:

AbstractHistological structure and neuronal geometry of the nucleus prethalamicus of holocentrid teleosts, which is homologous to the nucleus rotundus of reptiles and birds and to the nucleus lateralis posterior‐pulvinar complex of mammals, were studied by means of the Bodian, Nissl, toluidine blue, and Golgi methods. Synaptic terminals were classified electron microscopically, and terminal types originating from the telencephalon and the optic tectum were determined by electron microscopy in degeneration experiments.The nucleus prethalamicus is composed of four layers, in the following order from medial to lateral: a small‐cell layer, a plexiform layer, a large‐cell layer, and a marginal layer. Six types of terminals (U, L, Sp, Sd, F, andP) were distinguished in the nucleus, and the distribution pattern for each type of terminal was determined by counting its relative number in each layer. Sp terminals make synaptic contacts with small‐cell dendrites or somata in the small‐cell layer, and degenerate after telencephalic ablations.Sdterminals synapse exclusively with spines of large‐cell dendrites in both marginal and large‐cell layers, and degenerate after tectal ablations.Because only large neurons have been labeled after HRP injections into the telencephalon (Ito et al., '80, '82; Ebbesson, '80; Murakami et al., '83), it is considered that these neurons relay visual information from the optic tectum onto the telencephalon. It is hypothesized that the small neurons in the nucleus, which receive telencephalic input, might modulate the large neurons' r

ISSN:0092-7317    

DOI:10.1002/cne.902210404

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

年代:1983

数据来源: WILEY

摘要:

AbstractFeatures of the organization of the efferent axonal projections from the medial superior olivary nucleus (MSO) in the cat were studied. In order to determine the origin and distribution of projections from MSO, the retrograde horseradish peroxidase (HRP) and autoradiographic tracing methods were used. The results showed that (1) in both HRP and autoradiographic studies the projection to the inferior colliculus was largely ipsilateral, although a contralateral component was present; (2) the projection field of MSO was confined to the ventral division of the central nucleus of the Inferior colliculus, and within this field the labeling was heavier in the rostral and dorsolateral parts of the ventral division; (3) the projection to the inferior colliculus was topographic with ventral parts of MSO projecting ventrally and dorsal parts of MSO projecting dorsolaterally; (4) the projection field in the central nucleus formed successive laminae oriented from ventro‐lateral to dorsomedial; (5) the axonal course was via the medial or internal segment of the lateral lemniscus; and (6) some fibers in this course ended additionally within the dorsal nucleus of the lateral lemniscus. This latter projection was also topographically organized. These observations supported previously described features of lamination and tonotopic order for afferents of the inferior colliculus, as well as recent suggestions that functional segregation of afferent connections exists within the laminated portion of the central nucleus of the inferior colliculu

ISSN:0092-7317    

DOI:10.1002/cne.902210405

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe distribution of serotonin (5HT) in the brain of the Atlantic stingray was studied with peroxidase‐antiperoxidase immunocytochemistry and high‐pressure liquid chromatography. The regional concentrations of 5HT determined for this stingray fell within the range of values previously reported for fishes. A consistent trend in vertebrates for the hypothalamus and midbrain to have the highest concentrations and the cerebellum the lowest was confirmed in stingrays. Neuronal cell bodies and processes exhibiting 5HT‐like immunoreactivity were distributed in variable densities throughout the neuraxis. Ten groups of 5HT cells were described: (I) spinal cord, (II‐IV) rhombencephalon, (V, VI) mesencephalon, (VII, VIII) prosen‐cephalon, (IX) pituitary, and (X) retina. There were three noteworthy features of the 5HT system in the Atlantic stingray: (1) 5HT cells were demonstrated in virtually every location in which 5HT‐containing cells have been described or alluded to in the previous literature. The demonstration of immunopositive cells in the spinal cord, the retina, and the pars distalis of the pituitary suggests that 5HT may be an intrinsic neurotransmitter (or hormone) in these regions. (2) The distribution of 5HT cells in the brainstem shared many similarities with that in other vertebrates. However, there were many 5HT cells outside of the raphe nuclei, in the lateral tegmentum. It appears that the hypothesis that “lateralization” of the 5HT system is an advanced evolutionary trend cannot be supported. (3) 5HT fibers and terminals were more widely distributed in the Atlantic stingray brain than has been reported for other nonmammalian vertebrates on the basis of histofluorescence. It appears that this feature of the 5HT system arose early in phylogeny, and that the use of immunohistochemistry might reveal a more general occurrence of widespread 5HT fiber

ISSN:0092-7317    

DOI:10.1002/cne.902210406

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

年代:1983

数据来源: WILEY

摘要:

AbstractIncreases in the amount of periphery available for innervation have been achieved by the unilateral removal of hindlimb dorsal root ganglion (DRGs) inRana pipiens, a procedure which generally results in a compensatory cell number increase (hyperplasia) in the DRGs which remain. We have found that the hyperplastic response is extremely variable, and we have investigated various factors which might control its production. Our findings indicate, however, that the pattern of DRGs removed, the animal's age at the time of removal, and the survival period are not strictly related to the production of hyperplasia in hindlimb DRGs.Special emphasis has been placed on DRG 10, the caudalmost DRG which normally innervates the cloaca and sends a small projection to the hindlimb. This DRG displayed dramatic cell number increases of up to 564%. In addition, several unique features of the hyperplastic response have been observed in DRG 10. This DRG showed increases in cell number on both the operated and the unoperated sides. It showed hyperplasias in animals subjected to gangh'onectomy past metamorphosis as well as during larval development. Finally the production of DRG 10 hyperplasias exclusively occurred in male pre‐and postrnetamorphic animals. To account for these distinctive features of DRG 10 hyperplasia, baseline studies of the normal course of proliferation and cell death in DRG 10 were undertaken. They reveal no fundamental developmental differences between DRG 10 and other hindlimb DRGs. Other mechanisms responsible for these unusual features of developmental plasticity in DRG 10 are discusse

ISSN:0092-7317    

DOI:10.1002/cne.902210407

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

年代:1983

数据来源: WILEY

摘要:

AbstractCentral and peripheral connectivity patterns of hyperplastic dorsal root ganglia (DRGs) inRana pipiensare examined in order to determine the relative roles of peripheral and central contacts in the production of DRG hyperplasias. The hyperplasias are produced in the intact hindlimb DRGs after the removal in tadpoles and young postmetamorphic frogs of neighboring DRGs (Davis and Const an tine‐Paton, '83). The peripheral target zones of the hyperplastic DRGs, determined by physiological recordings of sensory receptive fields, are found to undergo a significant degree of expansion relative to controls. Peripheral expansion is most pronounced in caudalmost DRG 10, and this effect occurs in experimental animals operated during larval and postmetamorphic stages. Further, anatomical labelling of peripheral sensory fibers coursing to the hindlimb reveals that the hyperplastic DRG 10 actually contains additional fibers projecting to the denervated regions. The central projection of the hyperplastic DRG 10 does not show corresponding increases in longitudinal arborization after the application of horseradish peroxidase to the appropriate dorsal roots. These observations are made on some of the same experimental animals in which peripheral fields are shown to have vastly expanded. We conclude that the peripheral processes of the hyperplastic DRGs are less rigidly specified than the central terminations, and that it is the periphery which plays the primary role in controlling the cell numbers increases.A second aim of this investigation is to identify whether sexually dimorphic connectivity patterns in normal frogs explain the production of DRG 10 hyperplasias exclusively in male experimental animals (Davis and Constantine‐Paton, '83). We apply the same techniques used in our connectivity studies of hyperplastic DRGs to the investigation of connectivity patterns of DRG 10s in normal males and females. No sex‐dependent differences in peripheral and central connectivity are found. Thus, since normal male and female frogs possess an equivalent amount of target space for DRG 10, the unique production of hyperplasias in male experimental animals cannot be explained solely on the basis of connectivity. We speculate on what other factors may be inv

ISSN:0092-7317    

DOI:10.1002/cne.902210408

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

年代:1983

数据来源: WILEY

摘要:

AbstractPrimary afferent fibers transmitting impulses from slowly adapting (SA) Type I receptors in the glabrous skin of the hind paw of the cat were injected intraaxonally in the spinal cord with horseradish peroxidase (HRP).At the light microscopic level, terminal arborizations were observed in the medial dorsal horn extending up to 6 mm rostrocaudally in and near the seventh lumbar segment. Boutonlike swellings labelled with HRP were distributed in clusters in Rexed's laminae III‐VI. There was a tendency for the most dorsal clusters from an individual fiber to be located rostrally and for the most ventral clusters to be located caudally.At the electron microscopic level, a combination of morphometric analysis and serial reconstruction revealed the following: (1) All the boutons labelled with HRP contained predominantly clear, round synaptic vesicles, 40–50 nm in diameter. (2) Labelled boutons (n = 75) had cross‐sectional longest dimensions of 1.72 ± 0.53 μm (Mean ± S.D.), perimeters of 4.95 ± 1.52 μn, and areas of 1.18 ± 0.59 μm2. Their shapes in section varied from rounded to elongated forms. (3) The sizes of labelled boutons decreased significantly and linearly with depth from lamina IV to VI. The shapes of the bouton cross sections also became rounder with depth in the dorsal horn. (4) About 72% of synaptic contacts associated with HRP‐filled boutons were with dendritic spines and shafts; most of these synapses were of the asymmetric type. (5) The remainder (28%) of the appositions were synapselike contacts between labelled boutons and unlabelled structures containing flattened or pleomorphic vesicles, and occasional dense‐cored vesicles. (6) We observed no unequivocal axosomatic contacts made by labelled boutons. (7) The lengths of synaptic appositions with dendritic spines (0.46 ± 0.20 μm) or with dendritic shafts (0.51 ± 0.18 μm) were significantly greater than the synapselike contacts with vesicle‐containing unlabelled structures (0.29 ± 0.09 μm). (8) Complex neuropilar organization was occasionally seen with labelled boutons as central elements, although simpler organizations were much more common.In summary, HRP‐labelled fibers ended predominantly in boutons containing clear, round vesicles forming axospinous and axodendritic synapses. This is consistent with physiological observations of postsynaptic excitation of dorsal horn cells by the primary afferent fibers from SA Type I rece

ISSN:0092-7317    

DOI:10.1002/cne.902210409

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

年代:1983

数据来源: WILEY

摘要:

AbstractBy different denervation procedures the origin of dynorphin‐(1–17) and enkephalin immunoreactive fibers in the guinea pig inferior mesenteric ganglion was investigated. It was found that the dynorphin‐(1–17)‐positive fibers reached the ganglion predominantly via the colonic nerves and to a lesser extent via the hypogastric and intermesenteric nerves whereas the enkephalin‐positive fibers reached the ganglion via the lumbar splanchnic nerves. These findings show that the dynorphin‐(1–17) and enkephalin systems are separate i

ISSN:0092-7317    

DOI:10.1002/cne.902210410

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

年代:1983

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902210401

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

年代:1983

数据来源: WILEY