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关键词： Mouse   Gastrulation   Self-organisation   Symmetry breaking   Polarisation   Axial elongation   Endoderm   Mesoderm   Neural ectoderm   Pattern formation   Live cell imaging  

摘要： Mouse embryonic stem cells (mESCs) are clonal populations derived from preimplantation mouse embryos that can be propagated in vitro and, when placed into blastocysts, contribute to all tissues of the embryo and integrate into the normal morphogenetic processes, i.e. they are pluripotent. However, although they can be steered to differentiate in vitro into all cell types of the organism, they cannot organise themselves into structures that resemble embryos. When aggregated into embryoid bodies they develop disorganised masses of different cell types with little spatial coherence. An exception to this rule is the emergence of retinas and anterior cortex-like structures under minimal culture conditions. These structures emerge from the cultures without any axial organisation. Here, we report that small aggregates of mESCs, of about 300 cells, self-organise into polarised structures that exhibit collective behaviours reminiscent of those that cells exhibit in early mouse embryos, including symmetry breaking, axial organisation, germ layer specification and cell behaviour, as well as axis elongation. The responses are signal specific and uncouple processes that in the embryo are tightly associated, such as specification of the anteroposterior axis and anterior neural development, or endoderm specification and axial elongation. We discuss the meaning and implications of these observations and the potential uses of these structures which, because of their behaviour, we suggest to call 'gastruloids'.

关键词： Brain development   Embryo cultures   Erythropoietin   Hypoxia  

摘要： Background: Hypoxic ischemic encephalopathy continues to be a significant cause of death and disability worldwide. Erythropoietin (EPO) has the potential to lessen neurologic sequelae due to hypoxia ischemia. Methods: The in vitro effects of EPO on total embryonic development and brain VEGF receptor (VEGFR) expressions were investigated in 50 rat embryos at 9.5 days of gestation that were cultured in whole rat serum (WRS). According to the study protocol, the embryos were divided into two groups. The first group is comprised hypoxia, 100 and 50 U/ml EPO after hypoxia groups. Group 2 comprised control (WRS) and WRS EPO. After 48-h culture, the embryos from each group were harvested to be analyzed according to a morphological scoring system and also genetically to measure brain VEGFR expression. Results: The mean morphological scores for the embryos grown in control, WRS + EPO, hypoxia, and in the presence of 100 and 50 U/ml EPO in hypoxic medium were 55.30 +/- 7.22, 52.10 +/- 5.27, 23.0 +/- 4.60, 36.20 +/- 5.07, and 19.70 +/- 5.07, respectively. Expressions of VEGFR-1, -2, -3 were significantly elevated in the 100 Wail EPO and WRS + EPO groups compared to the hypoxia group (p < 0.05). Conclusions: These results support the conclusion that (1) VEGFR-1, -2, -3 may increase with EPO treatment in hypoxic conditions, (2) VEGF and EPO may be part of a selfregulated physiological protection mechanism to prevent neuronal injury including in utero neural tube defects. (C) 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

关键词： Cytoskeleton   Drosophila melanogaster   Morphogenesis   Individual-based model  

摘要： Syncytial embryos develop through cycles of nuclear division and rearrangement within a common cytoplasm. A paradigm example is Drosophila melanogaster in which nuclei form an ordered array in the embryo surface over cell cycles 10-13. This ordering process is assumed to be essential for subsequent cellularisation. Using quantitative tissue analysis, it has previously been shown that the regrowth of actin and microtubule networks after nuclear division generates reordering forces that counteract its disordering effect (Kanesaki et al., 2011). We present here an individual-based computer simulation modelling the nuclear dynamics. In contrast to similar modelling approaches e.g. epithelial monolayers or tumour spheroids, we focus not on the spatial dependence, but rather on the time-dependence of the interaction laws. We show that appropriate phenomenological inter-nuclear force laws reproduce the experimentally observed dynamics provided that the cytoskeletal network regrows sufficiently quickly after mitosis. Then repulsive forces provided by the actin system are necessary and sufficient to regain the observed level of order in the system, after the strong disruption resulting from cytoskeletal network disassembly and spindle formation. We also observe little mixing of nuclei through cell cycles. Our study highlights the importance of the dynamics of cytoskeletal forces during this critical phase of syncytial development and emphasises the need for real-time experimental data at high temporal resolution. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： dicofol   Colonel-S   chick embryo   insecticide   organochlorine   hepatotoxic  

摘要： In the present investigation, hepatotoxic effect of a commercially available insecticide formulation of dicofol (Colonel-S (R) 18.5% emulsified concentrate) was studied in the developing chick embryo. Fertilized eggs of Gallus domesticus were immersed in three different dose concentrations, i.e. 250, 500, and 1000mg L-1 of Colonel-S on 0 and fourth days of incubation for 60min at 37 degrees C and incubated till embryonic day 16. Severe histopathological cellular lesions, such as extensive cell degeneration and necrosis with enlarged blood sinusoids, cytoplasmic vacuolization, and leucocyte infiltrations with congestion or dilation of central vein, appeared in dose-depended manner. Dicofol treatment also caused significant decrease in the levels of total protein, glycogen, and glutathione content and an increase in alkaline phosphatase activity of embryonic liver, whereas glutamic pyruvic transaminase activity showed mixed response.

关键词： 团队教学   组织胚胎学   教学设计  

摘要： 目的通过以团队为基础的教学模式(TBL)在组织胚胎学课程中应用的教学设计,为TBL教学模式在组织胚胎学课程中的应用做好准备。方法根据学生学习成绩、知识结构、认知能力和性格特点等,采用互补的原则进行学生分组。按照教材内容顺序和内容知识的相关性分为10单元,教学单元既是知识的模块,也是教学段落。教学的四个重要环节:课前资料准备,课中测试监控和讨论,课后成绩的评定,期末成绩的评估和总结。结果相对于PBL和案例教学法,TBL的跨学科程度相对较低,更适合于低年级的基础医学课程的教学。结论经过精心设计,开始尝试在组织胚胎学的教学中使用TBL教学,并取得较好教学效果。

关键词： 组织学与胚胎学教学   学习兴趣   学习效率   学生  

摘要： 由于组织学与胚胎学内容繁多，抽象乏味，学生普遍反映学习兴趣和积极性不高，导致死记硬背，学习效率低下。为此，笔者从教以来，通过走访考察及对学生存在问题的了解，浅谈自己的几点看法及改进措施，希望能够使学生更加容易了解这门课的规律及意义，提高学习兴趣，提升教学成效。

关键词： 自我效能感   教学过程   胚胎学   组织学   教师   心理学家   操作行为   能力  

摘要： 自我效能感（self-efficacy）是由美国心理学家班杜拉于1977年提出的一个概念.他认为人们对自己能力的判断在其自主系统中起主要作用,自我效能感就是对自己在特定情境中是否有能力操作行为的预期.自我效能感理论提出以来,一直是较热门的研究主题[1-2],但国内相关研究尚处于起步阶段.

关键词： 口腔组织胚胎学   教学改革   措施   效果  

摘要： 口腔组织胚胎学是口腔组织病理学的组成部分,也是连接基础医学与临床医学的桥梁。由于课时紧,内容繁杂、抽象,教学难度较大。实践证明,运用多元化教学方法,激发学生对本课程的学习兴趣,带动学生学习,是提高教学效果的有效途径。

关键词： 组织胚胎学   学教并重   自主学习   学习品质  

摘要： 根据组织胚胎学课程特点,结合学校教改规划,构建"学教并重"的教学结构,编写了组织胚胎学学习指导方案,并以此为依托,采用"图"、"案"互动教学法,引导学生自主学习,学生的各方面能力得到了提高,提升了学生的学习品质。