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71.
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
72.
73.
Dietary protein and human pregnancy performance. 总被引:1,自引:0,他引:1
F J Zlatnik 《The Journal of reproductive medicine》1979,22(4):193-201
Low birth weight is an important predictor of neonatal mortality and morbidity. Women of low socioeconomic classes give birth to disproportionate numbers of low-birth-weight infants and eat poorer diets than those of higher classes. Although maternal weight gain in pregnancy is positively associated with birth weight, and although animal studies demonstrate the important effects of protein restricti-n on reproductive performance, the significance or lack thereof of diet in general and of protein intake in particular in pregnant women in generally well-nourished populations has not been established. The conflicting data on human pregnancy performance and diet are critically reviewed. 相似文献
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77.
A 22 year old male presented with symptoms of diffuse muscle pain and multiple abnormal laboratory findings that were eventually attributed to tropical myositis. Computed tomography scan was more reliable than ultrasound and served as a guide to needle aspiration and pathologic diagnosis. 相似文献
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80.
Alpha-thalassemia in two Mediterranean populations 总被引:5,自引:0,他引:5
Pirastu M; Lee KY; Dozy AM; Kan YW; Stamatoyannopoulos G; Hadjiminas MG; Zachariades Z; Angius A; Furbetta M; Rosatelli C; Cao A 《Blood》1982,60(2):509-512
We used restriction endonuclease analysis to determine the incidence of alpha-thalassemia in two Mediterranean islands. In a random population sample, the gene frequency of deletion-type alpha-thalassemia-2 (- alpha) was 0.18 in Sardinians and 0.07 in Greek Cypriots. All cases were the rightward crossover type. From these frequencies and the known incidence of hemoglobin-H disease in these populations, we calculated the frequency of the alpha-thalassemia-1 genotype (--) and determined that it was low. We also found that beta-thalassemia homozygotes in sardinia have a higher incidence of alpha-thalassemia than normals and beta thalassemia heterozygotes because a significantly greater number of these homozygotes are also homozygous for the alpha-thalassemia-2 lesion. These findings support the theory that coinheritance of alpha- thalassemia mitigates the severity of beta-thalassemia and suggest that the protection is most pronounced when two alpha-globin genes are deleted. 相似文献