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The ontogeny of large, globular, epidermal cytoplasmic inclusions (ECI) in P. virgatum roots was studied at the ultrastructural level. These ECI were seen to originate in meristematic cells as small electron translucent vesicles. Subsequently, the ECI, which appeared to be temporary storage sites, were seen to enlarge and increase in density by accumulating masses of a granular matrix as well as some small vesicular inclusions. In the zone of elongation, as the epidermal cells matured, the ECI within each cell gradually fused and the contents were lost. The pattern of the ontogeny of the ECI in the growing epidermal cells was consistent with the presence of cells of different physiologies in the zone of cell elongation of these roots. 相似文献
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William Jankowiak 《American anthropologist》2000,102(1):182-183
Women of Principle: Female Networking in Contemporary Mormon Polygyny. Janet Bennion. New York: Oxford University Press. 1998. 178 pp. 相似文献
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Reports that apoptosis within populations of neurotrophin-dependent neurones is virtually eliminated in BAX-deficient mice and that BAX-deficient neurones survive indefinitely in culture without neurotrophins have led to the view that BAX is required for the death of neurotrophin-deprived neurones. To further examine this assertion in vivo, we have studied two populations of NGF-dependent neurones during the period of naturally occurring neuronal death in mice that lack BAX, NGF or the NGF receptor TrkA, alone and in combination. In the superior cervical ganglion (SCG), naturally occurring neuronal death and the massive loss of neurones that took place in the absence of NGF or TrkA were completely prevented by elimination of BAX. However, in the trigeminal ganglion, naturally occurring neuronal death was only partly abrogated by the elimination of BAX, and although the massive neuronal death that took place in this ganglion in the absence of NGF or TrkA was initially delayed in embryos lacking BAX, this subsequently occurred unabated. Accordingly, BAX-deficient neurones survived in defined without NGF whereas BAX-deficient trigeminal neurones died in the absence of NGF. These results indicate that whereas BAX is required for the death of SCG neurones during normal development and when these neurones are deprived of NGF/TrkA signalling in vivo, the death of trigeminal ganglion neurones occurs independently of BAX when they are deprived of NGF/TrkA signalling. We conclude that BAX is not universally required for neuronal death induced by neurotrophin deprivation, but that there are major differences for the requirement for BAX among different populations of NGF-dependent neurones. 相似文献
110.
Using ethnographic data collected in a second grade classroom over the course of a school year, this paper describes the ways in which one school's discourse of liberalism is deleteriously deployed. We view the school's discipline creed as emblematic of the school's liberal curriculum, and interrogate the effects on four African American boys in the classroom when the school enacts this creed. Despite the agency that these boys obviously had, they were unable to control the ways in which they were placed at a structural disadvantage and manipulated by a system far more powerful than they were. The results were that these four boys suffered. Not only did the intended liberal curriculum fail to be translated fully into the enacted curriculum, the liberal underpinnings of this curriculum precluded teachers and students from taking any critical stance. 相似文献