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51.
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We sought to determine the effect of cholera toxin on small intestinal motor activity in the fasted state and relate it to secretion in conscious dogs. Motor activity was recorded by strain gauge force transducers and secretion was measured by diverting it to the outside through a two-way cannula. Inoculation of the study segment with cholera toxin resulted in a 10-fold increase in fluid output by 120 minutes postinjection. At the same time that fluid output increased Significantly changes in fasting motor activity occurred. The cycle length of the migrating motor complex was significantly reduced, the percentage of phase II activity was significantly increased, and migrating clustered contractions were inhibited. Perfusion of the study segment by a nonabsorbable electrolyte solution at a rate similar to the rate of secretion induced by cholera toxin did not change the cycle length of migrating motor complexes, but the percentage of phase II activity was significantly increased as with cholera toxin, and migrating clustered contractions were inhibited. The reduction in the cycle length of migrating motor complexes seems to be a direct effect of cholera toxin on the gut wall while the increase in percentage of phase II activity and inhibition of migrating clustered contractions appear to be indirect effects due to fluid accumulation. 相似文献
53.
Morphological variation of layer III pyramidal neurones in the occipitotemporal pathway of the macaque monkey visual cortex 总被引:5,自引:5,他引:0
We compared the morphological characteristics of layer III pyramidal
neurones in different visual areas of the occipitotemporal cortical
'stream', which processes information related to object recognition in the
visual field (including shape, colour and texture). Pyramidal cells were
intracellularly injected with Lucifer Yellow in cortical slices cut
tangential to the cortical layers, allowing quantitative comparisons of
dendritic field morphology, spine density and cell body size between the
blobs and interblobs of the primary visual area (V1), the interstripe
compartments of the second visual area (V2), the fourth visual area (V4)
and cytoarchitectonic area TEO. We found that the tangential dimension of
basal dendritic fields of layer III pyramidal neurones increases from
caudal to rostral visual areas in the occipitotemporal pathway, such that
TEO cells have, on average, dendritic fields spanning an area 5-6 times
larger than V1 cells. In addition, the data indicate that V1 cells located
within blobs have significantly larger dendritic fields than those of
interblob cells. Sholl analysis of dendritic fields demonstrated that
pyramidal cells in V4 and TEO are more complex (i.e. exhibit a larger
number of branches at comparable distances from the cell body) than cells
in V1 or V2. Moreover, this analysis demonstrated that the dendrites of
many cells in V1 cluster along specific axes, while this tendency is less
marked in extrastriate areas. Most notably, there is a relatively large
proportion of neurones with 'morphologically orientation-biased' dendritic
fields (i.e. branches tend to cluster along two diametrically opposed
directions from the cell body) in the interblobs in V1, as compared with
the blobs in V1 and extrastriate areas. Finally, counts of dendritic spines
along the length of basal dendrites revealed similar peak spine densities
in the blobs and the interblobs of V1 and in the V2 interstripes, but
markedly higher spine densities in V4 and TEO. Estimates of the number of
dendritic spines on the basal dendritic fields of layer III pyramidal cells
indicate that cells in V2 have on average twice as many spines as V1 cells,
that V4 cells have 3.8 times as many spines as V1 cells, and that TEO cells
have 7.5 times as many spines as V1 cells. These findings suggest the
possibility that the complex response properties of neurones in rostral
stations in the occipitotemporal pathway may, in part, be attributed to
their larger and more complex basal dendritic fields, and to the increase
in both number and density of spines on their basal dendrites.
相似文献
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Committee Reports: Committee on Affiliated Associations and Regional Branches: REPORT OF THE CHAIRMAN, 1966 下载免费PDF全文
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Committee Reports: Committee on Affiliated Associations and Regional Branches: REPORT OF THE CHAIRMAN, 1967 下载免费PDF全文
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