排序方式: 共有9条查询结果,搜索用时 0 毫秒
1
1.
Due to their small size, mammalian oocytes and embryos pose unique problems during preparation for transmission electron microscopy. This paper outlines a method which combines protein embedding with centrifugation to locate the specimens on the face of a Beem capsule mould. This method facilitates both the processing of oocytes with minimal loss and rapid location of the specimens within the block for simultaneous sectioning, staining and examination. 相似文献
2.
Ann M. C. Burgess 《Journal of microscopy》1983,130(1):123-124
A method is described which enhances the contrast of living and fixed specimens examined with the stereomicroscope. It consists of immersing the ends of flexible fibre optic light sources together with the specimen in the fluid used for examination. It is reported that not only does this method increase the contrast of living specimens but that it may also be applied to specimens being prepared as thin sections or freeze fracture surfaces for examination with the transmission electron microscope. A further method of enhancement of contrast is suggested which involves the fitting of light filters of complementary colours, one to each of the fibre optic light sources, before immersion with the specimen. 相似文献
3.
电磁辐射的危害、尤其对胚胎发育及子代的影响已引起人们的高度关注[1,2]。本研究对BALB/C雌性小鼠或雄性小鼠进行电磁脉冲照射(场强95.41kVm-1、3×106次和4×106次脉冲),受照雌鼠或雄鼠与未照的雄鼠或雌鼠于照后1天和2月分别交配,用胚胎畸形学的方法分别观察各组雌鼠的受孕率、孕鼠所产的胚胎数及其子代性别比等。经3×106次脉冲的电磁脉冲辐照后的各组,均留一部分孕鼠让其自然分娩,饲养仔鼠,仔鼠成年后采用Y型电迷宫法检测子代小鼠的学习记忆能力,同时将仔代小鼠放置于50℃金属平面上测量其对热伤害感受的反应潜伏期。经3×106次辐照… 相似文献
4.
绿豆种胚中离子注入深度的研究 总被引:11,自引:2,他引:11
通过SEM和SIMS检测到了离子注入以后绿豆种胚内部的铜元素和钛元素的浓度随深度的分布一形貌变化,说明了离子注入诱发为是带电粒子直接作用的结果。 相似文献
5.
目的探究食叶草粉对SD大鼠的母体毒性、胚胎毒性和致畸性。方法受孕SD大鼠按体重随机分组,每组不少于16只,设溶剂对照组(蒸馏水)和食叶草粉低、中、高剂量组(分别为0.42、0.84、1.67 g/kg.BW)。在受孕第6~15d,每日以10mL/kg.BW灌胃给予受试物或等量蒸馏水。观察、记录孕鼠临床表现和体重,于孕期第20 d称重并处死母鼠,检查孕鼠妊娠情况和胎鼠发育状况,包括黄体数、死胎数、吸收胎数、活胎数,胎仔性别、体重、体长、尾长,观察有无骨骼畸形和内脏畸形。结果将各剂量组的各项指标与溶剂对照组指标进行比较,差异无统计学意义(P>0.05)。结论食叶草粉在本实验条件下对SD大鼠无母体毒性、胚胎毒性和致畸性。 相似文献
6.
Sarah Nahon Viviana A. Castro Porras François Charles 《The Science of the total environment》2009,407(6):1892-1900
The sea urchin Sphaerechinus granularis was used to investigate the impact of relevant levels of UV-B radiation on the early life stages of a common Mediterranean free spawning benthic species. Sperm, eggs and embryos were exposed to a range of UV radiation doses. The resulting endpoints were evaluated in terms of fertilisation success, development and survival rates. Above a weighted UV radiation dose of 0.0029 kJ m− 2, fertilisation capability of irradiated sperm decreased rapidly. The exposure of the eggs to 0.0175 kJ m− 2 and more led to delayed and inhibited development with ensuing embryonic morphological abnormalities. One-day old larvae remained strongly sensitive to UV radiation as shown by the 50% decrease of the larval survival rate for a dose of 0.025 kJ m− 2 UVR. The elevated sensitivity of embryos to experimental UVR went along with a lack of significant amount of sunscreen compounds (e.g., mycosporine-like amino acids) in the eggs. The present results demonstrated that gamete viability and embryonic development may be significantly impaired by solar UV radiation in S. granularis, compromising in this way the reproduction of the species. Unless adaptive behavioural reproductive strategies exist, the influence of ambient UV radiation appears as a selective force for population dynamics of broadcast spawners in the shallow benthic Mediterranean environment. 相似文献
7.
8.
9.
Katja Wagner-Westerhausen 《Ethik in der Medizin》2008,20(1):6-16
Definition of the problem:
The current bio-ethical discussion on the moral status of human embryos is carried out on the foil of the philosophical understanding of the term person. At the same time, the irreconcilable differences between different ethical systems in the interpretation of the concept of person are the reason that no consensus can be found. The plurality of values is, last but not least, represented through the inconsistent – and thus dissatisfying – German legal situation.Arguments:
In the bio-ethical debate, to move away from the term person is beneficial to a consensus-orientated discussion. The attribution of moral rights cannot only be bound to the term person. Types of arguments that do not approach the topic through questions of status offer more plausible and satisfactory results.Conclusion:
Gradualistic concepts that gradate the protection of the embryo and measure it against other goods are unproblematic from a legal point of view and usually correspond to our intuition. Other possible alternatives, beyond the status debate, are the principles of genus solidarity, the interest in protecting norms, and cultural norms. The relational concept is a further expedient supplement to an approach based in individual ethics. 相似文献
1