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关键词： HIF-1 alpha   bHLH-PAS   embryo   heart   ventricular myocytes   EPAS1   gene expression   development   gallus gallus  

摘要： Hypoxia-inducible factor 1 (HIF-1) is composed of HIF-1 alpha and arylhydocarbon nuclear receptor translocator (ARNT), which belong to the basic-helix-loop-helix-Per/ARNT/Sim bHLH-PAS) family of transcription factors. HLF plays key roles in oxygen homeostasis and embryonic cardiovascular development. In this study, we have cloned cDNAs encoding the chick HIF-1 alpha from cultured embryonic ventricular myocytes (CEVM) and then examined its expression in various embryonic tissues. The deduced amino acid sequence of the chick HIF-1 alpha cDNA showed 79% identity with that of the human HIF-1 alpha cDNA. In contrast, sequence homology between the chick HIF-1 alpha and endothelial PAS protein 1 (EPAS1), another member of the bHLH-PAS proteins, was only low (49%). HIF-1 alpha mRNA was expressed abundantly in CEVM., but scarcely in the liver, which was quite different from expression pattern of EPAS1 mRNA. These data suggest that HIF-1 alpha may be involved in embryonic cardiovascular development. HIF-1 alpha and EPAS1 may play distinct roles during developmental stages. (C) 2001 Academic Press.

关键词： 组织胚胎学   实验教学   教学工具   显微镜  

摘要： 作者通过组织胚胎学实验课教学的实践,体会到重视实验教学,引导学生领略镜下的微细之美,培养其掌握辨认、描述人体微细结构的能力,是实验课的根本任务.本文从实验课教学的目的、教学工具的应用和实验作业等几个角度阐述了自己对实验教学的认识和体验.

关键词： 组织胚胎学   组织学  

摘要： 组织胚胎学是基础医学中的形态学科之一,其最大特点是所描述的形态结构在宏观条件下无法观察到,而理解结构时又要求建立三维空间思维,故学生在学习中常常感到抽象、枯燥、甚至乏味,这对我们组织胚胎学教师就提出了更高的要求. 现就组织胚胎学理论授课的实践,谈谈切身的一些体会.　　首先,教学中应注重培养学生的学习兴趣,充分利用各种形态学教具,如:幻灯片、挂图、模型等,必要时加以版图进行动态教学,尽量避免单调的口头描述,这样可以刺激学生的听觉和视觉,调动抽象思维,让学生在微观世界里遨游.其次,教学中应遵循教师主导和学生主体相结合的原则,采用启发式教学,其最简便易行的办法就是进行问题教学.通过一问一答,引导、点拔、启迪学生自行推理、思维.经过这一连串的启发提问,学生不但复习了学过的知识,并且对新知识易理解和记忆.再次,教师的授课语言力求精炼、准确而富有生动形象和幽默感.通过形象、恰当的比喻来帮助学生理解,让这些抽象的结构在学生脑海中逐渐变得具体、清晰.　　经过几年的教学实践,逐步总结了教学中各种经验教训,形成了自己的风格.当然,授课是师生的双边活动,也是教与学的配合过程,其目的就是帮助学生在脑海中构建出组织胚胎学的微细结构,帮助他们为以后相关的后续课程打下良好基础.

关键词： 软骨组织   同种异体   组织工程  

摘要： 目的研究探讨同种异体组织工程化软骨在动物体内形成。方法取怀孕 100 d胚胎羊的关节软骨经体外制成细胞生物材料复合物，并注射到异体羊腹壁皮下，每隔 2周取材，连续半年，对所取标本进行评价。结果在同种异体动物体内能形成软骨组织并与正常软骨组织有相似的组织学特性。第 2、 4周的软骨组织有一定程度的免疫排斥反应和炎症细胞浸润。第 6周免疫反应减轻。结论应用组织工程技术可在同种异体动物体内再生软骨组织，再生的组织周围存在一定程度的免疫反应，随接种时间的延长而逐渐减弱。

关键词： 组织学与胚胎学   多媒体教学   髓鞘   神经组织  

摘要： 组织学与胚胎学是一门重要的医学基础学课,与其他基础学课及临床各科关系密切,因此学习好组织学与胚胎学十分重要.但由于其是形态学课,学生学习起来感到枯燥乏味,学习积极性不高、兴趣不大.因此,在进行教学改革中,除了激发学生对组织学与胚胎学的兴趣,使他们认识到组织学与胚胎学和医学各科的联系及重要性外,还要用生动的教学方法,使本来枯燥无味、难以理解的形态变得容易理解掌握的知识.多媒体教学就是这样一种比较好的教学方法.它要求教课教员以课本教学内容为基础,结合大量图片及由此制作的动画,将本来单调难讲的知识,形象地动态地展示在学生面前,使学生能很容易理解并记住.比如,在讲解神经组织时要给学生讲髓鞘细胞包饶神经细胞突起形成髓鞘的过程,以往如果单凭教员口头讲解,学生也可能只听懂个大概,如果用多媒体的动画效果,可以形象地显示髓鞘细胞如何一步一步地包饶着突起,最终形成髓鞘,学生看了可以一目了然.尤其在这个网络时代,计算机技术发达,更为多媒体教学提供了条件.将平时上课用的多媒体内容放到教学网站上,学生可能通过上网浏览,为学生自学和复习提供方便.当然,多媒体教学对教员的要求提高了,使得我们教员们只有不断地学习提高,才能跟得上这个时代的需要,才能更好地教好学生,使学生掌握知识更牢固.

关键词： bromoindole-3-carbaldehydes   cytotoxicity   sea urchin eggs   Stomoza murrayi   structure-activity relationship  

摘要： Natural derivatives of indole-3-carbaldehyde were isolated from the tropical marine ascidian Stomoza murrayi. A series of 13 derivatives, three natural and 10 synthetic (brominated and N-methylated), were examined for their effects on cell division of sea urchin eggs. These derivatives were shown to inhibit the first mitotic cycle in a concentration-dependent manner. By comparing the IC50 values with the structure of the various molecules, we were able to determine that bromination increased the cytotoxicity of the compound with a maximum occurring when bromine was added to carbon number 2, while addition of N-methylation was shown to markedly reduce the cytotoxicity of these same compounds brominated at carbon 2 only. Biological activity of this family of compounds has been characterized, via detailed study of addition of the most active derivative, 2,5,6-tribromoindole-3-carbaldehyde, on macromolecule synthesis and cytoskeleton reorganization during the first mitotic cycle of fertilized sea urchin eggs. Fluorescence localization of chromatin and microtubules revealed that 2,5,6-tribromoindole-3-carbaldehyde allowed pronuclei migration and fusion but prevented the condensation of chromatin, nuclear envelope breakdown, and bipolar mitotic spindle assembly, inducing an arrest of sea urchin embryogenesis at the beginning of mitosis. It is postulated here that this phenotype is likely to be due to a strong inhibition of DNA replication and protein synthesis.

关键词： transplant   lipophilic probe Dil   neocortex   confocal microscopy  

摘要： The effect of implanted embryonic nervous tissue on restoration of axonal connections in the cerebral cortex after mechanical injury was studied on albino rats using fluorescent lipophilic probe DiI (1,1'-dioctadecyl,3,3,3',3'-tetramethyl-indocarbocyanine perchlorate) and confocal laser scanning microscope. Implantation of embryonic tissue to damaged area promotes the growth of axons through the transplant to adjacent tissue. The damaged area is impenetrable for axons growing without implantation.

关键词： cell lineage   photoreceptor differentiation   retina regeneration   retina transplantation   tissue engineering  

摘要： Plasticity of photoreceptors and their integration into epithelial structures homologous to an outer nuclear layer (ONL), was investigated in embryonic chick retinal cell reaggregates by immunohistochemistry using an antibody specific for red plus green cones (RG-cones) and an antibody for rods. If reaggregates are raised in the presence of pigmented epithelium (RPE), completely reconstructed, stratified retinal spheres are produced, where all rods and cones are integrated into an outer laminar ONL, similar to a normal retina. In the absence of RPE, 'rosetted' spheres form which contain internal rosettes homologous to an ONL. Only a minor fraction of cones and rods of 'rosetted' spheres are located within rosettes, while a larger fraction is diffusely displaced in nonorganized areas, thus, not contributing to an ONL-like epithelium. In both types of spheres, the total percentage of RG-cones was similar to the in vivo retina, indicating that expression of cones is autonomous. Following cones, after about one day, rods developed only within already existing RG-cone clusters. Thereby, the ratio of rods to RG-cones increases as the tissue organization decreases: for stratified spheres this ratio is, 0.50 (1 rod/2 cones;similar to mature retina);for rosettes, 0.74 (3 rods/4 cones) and for nonorganized areas, 1.09 (1 rod/1 cone) - a higher ratio under our conditions has never been detected. Thus, rod expression depends strictly on the presence of nearby cones;their relative numbers are distinctively adjusted according to the cytoarchitecture of the tissue environment. The biomedical implications of these findings are briefly discussed.

关键词： CARROTS   PLANT embryology   PLANT growing media   BREEDING  

摘要： Carrot (Daucus carota L. F1 hybrid Starca) excised hypocotyls were cultured on Murashige and Skoog medium with and without 2,4-dichlorophenoxy acetic acid (2,4-D) to determine the effect of this plant growth regulator on their further development and their endogenous hormone levels, Culture in the absence of 2,4-D stimulated root development at one end of the hypocotyl segments and increased the endogenous bevels of free indole-3-acetic acid (IAA), zeatin/zeatin riboside and N-6(Delta (2)-isopentenyl) adenine/N-6(Delta (2)-isopentenyl) adenosine, as determined by radioimmunoassay. On the other hand, the presence of 2,4-D in the culture medium promoted callus induction and proliferation, together with abscisic acid (ABA) accumulation, in the hypocotyl segments during the first weeks of culture. When the callus segments generated in the hypocotyl sections cultured in the presence of 2,4-D were cultivated further, the development of two callus types was observed, one composed of preglobular and globular embryos and the other translucent, watery and lacking any sign of organisation. The embryos of the first type germinated when callus segments were transferred to regeneration conditions, while no change was observed when the second type was induced to regenerate, Higher levels of free IAA and ABA were obtained in the embryogenic calli when compared to the non-embryogenic, while no differences were observed among callus types in the other hormones evaluated. The possible role of the different plant hormones during induction of somatic embryogenesis is discussed.

关键词： 组织学   胚胎学   多媒体教育   医学教育  

摘要： 随着近代医学科学的迅猛发展，多学科知识的相互渗透，形成组织学与胚胎学这门学科课程内容繁杂，结构细微、理论抽象、信息量增大。由于教学时数减少，学校扩大招生，上课分班人数增多，学生划分多层次，多专业学习要求，面对这些教学压力，传统的教学手段已不能适应新时期教学发展的要求。以计算机为中心的多媒体技术已成为教学过程中不可缺少的组成部分，对促进教学改革，提高教学效率，提高教学质量很有帮助。我室在97、98级本科三年的组织学与胚胎学的理论教学中，全部采用计算机多媒体教学方式，取得满意的教学效果。为了解发现计算机教学组织与实施中的问题，总结多媒体在本学科教学中的固有特点和内在规律，从而为完善教学设计，开发新的教学模式提供科学依据。为此我们作了教学效果的问卷检查，本文就此对调查结果作初步分析。