摘要:

AbstractAn atlas of neurons in the brain of the crayfishCherax destructorthat are immunoreactive to antibodies raised against serotonin has been compiled from whole mount preparations. Neuronal networks of serotonin‐containing cells are identified in the optic lobes and protocerebrum, in the deutocerebrum, and in the tritocerebrum. The consistency of the whole‐mount technique allows 50 out of a total of about 100 immunoreactive cells to be individually identified according to their neuronal architecture or the location of their cell somata or axons. Apart from six neurons with axons in the oesophageal connectives, all the immunoreactive cells are intrinsic to the optic lobes and br

ISSN:0092-7317    

DOI:10.1002/cne.902690402

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractFine visual sampling in the macaque depends on the high density of cone outer and inner segments in the fovea. Cone pedicles, at the opposite, presynaptic end of the cone, are absent from the center of the fovea. Both ends of the cones, inner segments and pedicles, are closely packed within their respective monolayers, but the spatial density of foveal pedicles is lower because foveal pedicles are wider than inner segments. Because there is one pedicle for every inner segment, and because pedicles are wider than inner segments, increase in eccentricity finds increasing lateral displacement of the cone's pedicle from its inner segment. Further increase of eccentricity finds inner segment density falling below pedicle density, and so this lateral displacement declines. By 2–3 mm from the center, inner segments catch up with pedicles. Additional lateral displacements, of bipolar cells from pedicles and ganglion from bipolar cells, are largest for central‐most elements and fall steeply with eccentricity.By taking into account all of these lateral displacements, the eccentricity of the cone inner segment(s) associated with a ganglion cell was determined, as was the area of inner segments represented by a unit area in the ganglion cell layer. Then raw ganglion cell densities were transformed to densities comparable to densities of inner segments and of cells in dorsal lateral geniculate nucleus. On average there appears to be close to 2 ganglion cells for each cone in the central fovea out to about 2.5°. Thus, the density of foveal ganglion cells is sufficient to allow each red and each green cone to connect to 2 midget ganglion cells, and each blue cone to connect to 1 ganglion cell. Furthermore, there appears to be a single dorsal lateral geniculate cell for each ganglion

ISSN:0092-7317    

DOI:10.1002/cne.902690403

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe compartmental organization of the amygdalostriatal projection was studied in the cat by comparing staining patterns seen by cholinesterase enzyme histochemistry with the distribution of fibers labelled with a horseradish peroxidase–wheat germ agglutinin conjugate or by incorporation of35S‐methionine or3H‐leucine. Fibers from the basolateral nucleus of the amygdala were found to innervate selectively acetylcholinesterase‐poor striosomes demonstrated in the caudate nucleus and butyrylcholinesterase‐rich zones observed in the anterodorsal nucleus accumbens. In no case were the amygdalar fibers fully restricted to striosomes, but the nature and degree of labelling of the striatal matrix, as well as the range of the labelled fibers in dorsal striatum, varied with the positions of the inject

ISSN:0092-7317    

DOI:10.1002/cne.902690404

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe glyoxylic‐acid‐induced fluorescence technique was applied to demonstrate patterns of catecholaminergic innervation within the auditory brainstem of echolocating bats and the house mouse. In the cochlear nucleus of the rufous horseshoe bat (Rhinolophus rouxi) and the mustache bat (Pteronotus parnelli), species‐specific catecholaminergic innervation patterns are found that contrast with the relatively homogeneous innervation in the rodent.In both bats the subnuclei of the cochlear nucleus receive a differentially dense supply of catecholaminergic fibers, and within the subnuclei, the catecholamine innervation densities can be correlated with the tonotopic frequency representation. The areas devoted to the high‐frequency echolocation calls are less densely innervated than those regions which are responsive to lower frequencies.Apart from this common scheme, there are noteworthy distinctions between the two bats which correlate with specialized cytoarchitectural features of the cochlear nucleus. The marginal cell group, located medially to the anteroventral cochlear nucleus of Pteronotus, receives the densest supply of catecholaminergic fibers of all auditory nuclei. This plexus is formed by a morphologically distinct population of catecholaminergic

ISSN:0092-7317    

DOI:10.1002/cne.902690405

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractTransplants of fetal central nervous system (CNS) tissue into the acutely injured rat spinal cord have been demonstrated to differentiate and partially integrate with the adjacent host neuropil. In the present study, we examined the potential for applying a transplantation approach to chronic spinal cord lesions. In particular, we were interested in learning whether host‐graft fusion would be adversely affected by an advanced histopathology characterized in part by glial scar formation.Hemisection cavities were prepared at lumbar levels of the adult rat spinal cord 2–7 weeks prior to the transplantation of spinal cord tissue obtained from 14‐day rat fetuses. Graft survival, differentiation, and integration with the host spinal cord were subsequently evaluated by light microscopic techniques at post‐transplantation intervals of 1–6 months. Immunocytochemistry was also employed to examine the extent of astrocytic scar formation at the host‐graft interface and serotoninergic innervation of the grafts. In some other cases, anterograde and retrograde transport of wheat germ agglutinin‐conjugated horseradish peroxidase was used to determine whether axonal projections were formed between the host spinal cords and grafts.By 2 weeks after injury the initial lesion cavities were surrounded by a continuous astrocytic scar which remained intact for at least 7 weeks after injury in nongrafted control animals. In other animals, transplantation into these advanced lesions resulted in well‐differentiated grafts with a 90% long‐term survival rate. Although dense gliosis was still present along the lesion surfaces of the recipient spinal cord, foci of confluent host‐graft neuropil were observed where interruptions in the scar had occurred. Donor tissue integrated most often with the host spinal cord at interfaces with host gray matter; however, some implants also exhibited sites of fusion with damaged host white matter. Thus, some regions of confluent graft and host neuropil could be routinely identified, despite the presence of a dense glial scar along the walls of the chronic lesion site at the time of transplantation. Anterograde and retrograde tract‐tracing results suggested that some axonal projections into these grafts had originated from host neurons located immediately adjacent to the donor‐recipient interface. In addition, immunocytochemistry revealed some host serotoninergic axons (presumably of supraspinal origin) traversing nongliotic interfaces.The results of this study raise the possibility that grafted fetal CNS tissue has a capacity for stimulating partial regression of an established glial scar. On the other hand, if the integrity of the scar was inadvertently disturbed during transplantation, then the presence of fetal spinal cord tissue may have tempered a secondary glial response. In either case, the present demonstration of some graft‐host neuropil integration and axonal interaction establishes a useful framework for future studies directed at the ultimate goal fo functional restoration in the chroni

ISSN:0092-7317    

DOI:10.1002/cne.902690406

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractRetinae from embryonic mice were transplanted to the occipital cortex of neonatal rats together with their normal target regions, tectum or diencephalon, from embryonic mice or rats. In control experiments, retinae were cotransplanted with embryonic rat occipital cortex. In over 80% of the experimental animals, both transplants differentiated and grew. Ganglion cells in the retinae cotransplanted close to tectum or diencephalon survived for at least 15 weeks. Their survival was associated with the development of a distinct optic fiber layer and outgrowth of axons from the transplanted mouse retina. Specific innervation of distinct patches within the cotransplanted rat tectum or diencephalon was demonstrated by the use of an anti‐mouse antibody. The innervated regions, which could be as far away as 1.3 mm from the retinae, were correlated with cytological features of the Co‐transplanted tectum or diencephalon. By contrast, the host cortex was never innervated by the transplanted retinae. In the control animals in which the retinae were cotransplanted with occipital cortex and in four animals in which the cotransplants lay more than 2.7 mm apart, no ganglion cells were identified and there was no evidence of an optic fiber layer, outgrowth of axons, or innervation. These results support the idea that in order to survive, retinal ganglion cells need to innervate an appropriate target region. Further, the specific innervation of regions within the cotransplanted tectum or diencephalon suggests that these target regions are able to exert a tropic influence on the axons of retinal ganglion cells, even in the absence of many of the normal structure c

ISSN:0092-7317    

DOI:10.1002/cne.902690407

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIndividual optic arbors, normal and regenerated, were stained via anterograde transport of HRP and viewed in tectal whole mounts. Camera lucida drawings were made of 119 normal optic arbors and of 242 regenerated arbors from fish 2 weeks to 14 months postcrush. These arbors were analyzed for axonal trajectory, spatial extent in the horizontal plane, degree of branching, number of branch endings, average depth, and degree of stratification. Normal optic arbors ranged in size from roughly 100 to 400 μm across in a continuous distribution, had an average of 20 branch endings with average of fifth‐order branching, and were highly stratified into one of three planes within the major optic lamina (SO‐SFGS). Small arbors arising from fine‐caliber axons terminated in the most superficial plane of SO‐SFGS; large arbors from coarse axons terminated in the superficial and middle planes; and medium arbors from medium‐caliber axons terminated in the middle and deep planes of SO‐SFGS, as well as deeper in the central gray and deep white layers. Arbors from central tectum tended to be much more tightly stratified than those in the periphery. No other differences between central and peripheral arbors were noted.Mature regenerated arbors (five months or more postcrush) were normal in their number of branch endings, order of branching, and depth of termination. Their branches covered a wider area of tectum, partially because of their early branching and abnormal trajectories of branches. Axonal trajectories were often abnormal with U‐turns and tortuous paths. Fine‐, medium‐, and coarse‐caliber axons were again present and gave rise to small, medium, and large arbors at roughly the same depths as in the normals. There was frequently a lack of stratification in the medium and large arbors, which spanned much greater depths than normal. Overall, however, regenerates reestablished nearly normal morphology except for axonal trajectory and stratification.Early in regeneration, the arbors went through a series of changes. At 2 weeks postcrush, regenerated axons had grown branches over a wider‐than‐normal extent of tectum, though they were sparsely branched and often tipped with growth cones. At 3 weeks, the branches were more numerous and covered a still wider extent (average of five times normal), many covering more than half the tectal length or width. At 4–5 weeks smaller arbors predominated, although a few enlarged arbors were present for up to 8 weeks. Additional small changes occurred beyond 8 weeks as the arbors became progressively more normal in appearance. The number of branch endings increased from 2 to 4 weeks and dropped slightly between 4 and 6 weeks. This drop, although it did not reach statistical significance, was correlated with the drop in size of the arbors and with the time of sharpening of the retinotopic map. Stratification of the regenerated arbors was poor, improved only very slowly as the arbors matured, and never returned to normal. These findings indicate that the widely branched arbors are a transient stage in regeneration, corresponding to the early diffuse retinotopic map before sharpening. The time of the widely branched arbors and the elimination of extraneous branches corresponds to the period of maximum sensitivity to strobe and to TTX demonstrated in other studies. The role of activity in refini

ISSN:0092-7317    

DOI:10.1002/cne.902690408

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractStudies of albino rodents have shown that an absence of pigment in the developing optic stalk may alter the position of the first retinal fibers that grow toward the brain, thereby disrupting the gross topographic relationship of fibers in the nerve (Silver and Sapiro:J. Comp. Neurol. 202:521–538, ′81). The abnormalities associated with albinism are more extensive in the Siamese cat than in previously studied species. Therefore, any abnormalities in differentiation of the stalk and axon guidance may be more readily detected. To investigate the guidance and/or misguidance of optic axons, light and electron microscope analyses were made of serial sections through the optic stalk in normally pigmented and Siamese fetal cats.On E20, before axons enter the optic stalk, the only clear morphological distinction between Siamese and normal cats is the distribution of pigment in the stalk. Pigment is found in the dorsal stalk cells of the normal cat for 200 μm from the optic disc. Although the retinal pigment epithelium of the Siamese cat embryo contains pigment, pigment could not be detected in the Siamese optic stalk. By E23 axons invade the ventral optic stalk in both strains. Concurrent with the early stages of axonal exit from the retina, there is complete separation of the stalk's dorsal and ventral tiers. As the cleavage occurs, basal lamina invaginates into the zone of separation following along the plane of the old lumen. The ventral stalk fills with axons while the dorsal tier is shed gradually. In contrast, in the Siamese cat, dorsal stalk cells are not sloughed off properly and instead are incorporated ectopically into the nerve. Basal lamina invagination is irregular. Axons do not fill the Siamese stalk symmetrically but enter the region of ectopic cells, which in turn disrupts gross fiber position. Usually, in the mutant, axons originating from the retina temporal to the optic fissure are those that invade the dorsal tier of ectopic cells. The altered position of optic axons in the mutant stalk may provide an explanation for the chiasmatic misrouting of optic axons in this spe

ISSN:0092-7317    

DOI:10.1002/cne.902690409

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe propriospinal system, which consists of those neurons completely contained within the spinal cord, is important because it underlies much spinal behavior. To provide quantitative data on this system, the present study determines numbers of axons in the isolated S2 cat spinal cord and compares these figures with the normal. The conclusion is that 60% of the fibers in the spinal cord at this location are propriospinal. Findings of particular interest are that the great majority of unmyelinated propriospinal axons are found in the dorsal part of the lateral funiculus, and that there are large numbers of descending myelinated fibers in the dorsal funiculi. These data will serve as a basis for evaluating axon numbers that follow various experimental regimens purporting to result in neural sprouting.

ISSN:0092-7317    

DOI:10.1002/cne.902690410

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902690401

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY