甲基胆蒽对蝾螈中胚层分化的影响

前言对哺乳类有引瘤作用的物质,在两栖类的成体中,不论是有尾类(Breedis,1951,1952;和,1954)或者无尾类(曾弥白,1956a),都可以引起恶性瘤肿,虽然瘤肿形成的频率远没有在哺乳类高。对于两栖类幼体,或者正在发育中的胚胎组织,引瘤物质却表现了不同的作用。它们可以引起形态建成的变化。Waddington 和 Needham(1935)将多种多环碳氢化物塞入早期原肠胚的囊胚腔,发现其中几种诱导了神经组织的发生。为了避免塞入法可能引起的机械的影响,沈诗章(Shen,1942)用二苯骈蒽内琥珀酸钠(Na-dibenz-anthracene-endo-succinate)的水溶液处理早期原肠胚的预定表皮,也得到了同样     

小鼠胚胎组织、成体组织和胚胎癌细胞酯酶同功酶谱的比较研究

本文比较了129品系小鼠几种胚胎组织及其相应的成体组织的酯酶同功酶谱。几种胚胎组织都可检测到共同的具有相同迁移率的C区酶带和E区酶带。在这些胚胎组织的功能发育过程中,C区酶带被其它区带所取代;E区酶带在成体组织中有的活性降低,有的完全消失。从这些比较分析中可以观察到酯酶同功酶从“胚胎型”向“成体型”的转变。与这些结果相对应,F9-1和B7-2胚胎癌细胞克隆株及来源于早期胚胎细胞的细胞系细胞也都具有酯酶C和E的活性。     

Noggin基因与中枢神经系统发育的研究进展

Noggin作为一种重要的胚胎蛋白,在胚胎背腹轴模式形成、神经管发育及神经诱导方面有重要功能。干细胞研究的新进展提示,中枢神经系统发育将持续至生后及成年,包括胚胎及成体干细胞的增殖与分化,而noggin通过拮抗骨形成蛋白（BMPs）参与胚胎及成体干细胞的增殖与分化。本文就noggin基因在中枢神经系统发育中的重要功能予以阐述。     

干细胞概述

干细胞是存在于胚胎和成体中的一类特殊细胞,它能长期地自我更新,在特定的条件下具有分化形成多种终末细胞的能力,不同来源的干细胞分化潜能各异。从早期胚胎内细胞团分离的胚胎干细胞能分化形成个体所有的细胞类型,并具有在体外无限增殖的能力,是最具有临床应用前景和研究价值的干细胞之一。在成体各种组织和器官中也存在成体干细胞,用于维持机体结构和功能的稳态。近期有关成体干细胞可塑性的研究和成体组织中多能干细胞存在的证据扩大了人们对成体干细胞分化潜能的认识。干细胞具有的多向分化潜能和自我更新能力使其成为未来再生医学的重要种子细胞,并成为研究人类早期胚层特化和器官形成、药物筛选以及基因治疗的最佳工具。     

瑞士发现幻龙胚胎化石

迄今爬行动物胚胎化石中被详细描述过的还只有唯一的一个例子,即鱼龙的胚胎。最近,瑞士苏黎世大学古生物学家发现了幻龙的胚胎化石,地点在瑞士南部和意大利北部,地质年代属于2.3亿年前的三叠纪。幻龙是一种小型的肿肋龙,成体总长只有230至370毫米,外形象蜥蜴,栖息于温暖的沿海浅水中。幻龙是该地区最多的化石爬行动物。目前大约有800号标本保存在苏黎世大学古生物学研究所和博物馆内。在97具制备好的标本中,24具属于幼年标本,它们从小到大,可以形成一个完整的生长序列。其中大的标本已经达到性成熟。这些标本中最小的一个,体长只有51毫米,只有成体平均体长的22%,可能为已知的最小的爬行动物化石。现在这样大小的爬行动物在达到成体体长30%     

小鼠胚胎干细胞移植入成体大鼠脑内的区域特异性存活与分化

全能区域非特异性的胚胎干细胞是研究成体不同脑区控制干细胞分化能力的十分有力的工具。胚胎干细胞源性神经前体细胞移植入成体脑后可分化为功能性神经元,但是未分化的胚胎干细胞在成体脑内各个部位的存活、生长与分化的潜能差异尚不清楚。本文旨在探讨成体脑组织对胚胎干细胞的影响及胚胎干细胞在成体脑内的一系列行为。将少量转绿色荧光蛋白未分化的小鼠胚胎干细胞移植入成体大鼠脑内不同部位,分别于移植5、14和28d后处死大鼠,进行形态学观察及免疫组化定性,以了解未分化的小鼠胚胎干细胞在大鼠脑内不同区域的存活、生长与分化。结果发现未分化的小鼠胚胎干细胞可逐步整合入受体组织并向nestin阳性神经前体细胞分化。移植细胞及其后裔在海马生长最为旺盛,而在隔区最差（P〈0．01）;移植细胞分化为神经干细胞的效率也是在海马最高,而在隔区最低（P〈0．01）。提示只有部分脑区适合胚胎干细胞及其后裔生存,并提供促进其分化的有益环境。因此,由于位置特异的微环境因子及环境因素的存在,宿主组织特性对决定中枢神经系统疾病的细胞替代疗法策略是相当重要的。     

成年人骨髓干细胞研究

关于“胚胎干细胞”研究及其发展的伦理之争一直没有停止 ,特别是“胚胎干细胞克隆”的研究 ,因为它涉及的面更为广泛而敏感 ,争议也更为激烈。为避开这些 ,使研究工作得以健康稳步地发展 ,非胚胎干细胞的研究及其应用也不亚于胚胎干细胞而显现出它的生命力。美国明尼苏达大学研究人员发现成年人体内 (如骨髓 )有与胚胎细胞一样分化潜能很强的干细胞 ,并认为它有可能分化成任何类型的组织 ,其分化能力之强可与胚胎干细胞相媲美 ,他们把这类成体干细胞称之为“多能成体祖细胞”。所谓多能是指该“祖细胞”能分化成心肌、大脑、肝脏、皮肤和各…     

若尔盖湿地高原林蛙和岷山蟾蜍的日活动节律

2005年调查若尔盖湿地的高原林蛙（Rana kukunoris）和岷山蟾蜍（Bufo minshanicus）的日活动节律,发现阳光充足时两栖类的活动性明显高于多云天气;高原林蛙成体、亚成体、岷山蟾蜍亚成体活动的最低气温为0℃、2℃、8℃;高原林蛙亚成体日活动高峰为中午12：30左右,岷山蟾蜍亚成体日活动高峰为下午15：30左右;高原林蛙亚成体在草地、林地、河边均有一定数量个体活动,岷山蟾蜍亚成体主要集中在河边活动。在若尔盖地区,两栖类可能主要是采用晒太阳（basking）的行为来适应高海拔环境;高原林蛙成体对温度的耐受性比亚成体高,亚成体比岷山蟾蜍亚成体高;高原林蛙与岷山蟾蜍的亚成体在活动时间与活动生境上存在差异,可能是减少种间竞争的途径之一。     

Rohon-Beard细胞在东方蝾螈神经胚中的定位

自从我们观察到两栖类胚胎的表皮在一定的发育阶段能够传导兴奋性,很自然地想到表皮细胞与中枢神经系统的联系的问题,想到Rohon-Beard细胞(以下简称R.-B.细胞)。R.-B.细胞自从1860年在七鳃鳗被发现以来,在无尾两栖类的青蛙、蟾蜍、铃蛙都被找到。在有尾类的钝口螈胚胎,Coghill在1914年进行了经典的,比较系统的研究,相当精细地叙述了这种细胞的发育,联系到胚胎的早期行为,他认为这些细胞是躯干部最早的感觉细胞,在背部的感觉神经节建立之前,执行感觉的功能,尽管那时关于兴奋是怎样传入到这种细胞的,还没有定论。     

一种在两栖类胚胎的免疫组织化学研究中有多种用途的方法

本文介绍了我们最近发展的一项用于两栖类胚胎的免疫组织化学研究的技术。两栖类胚胎经过适当的化学固定以后,用振动切片机可以得到50—100 μ的切片。我们用这样的切片进行免疫萤光和免疫酶标染色,均得到满意的结果,可以进行光镜(共聚焦显微镜,普通显微镜)及透射电镜的观察。由于在整个过程中避免了使用有机溶剂及包埋剂,所以最大限度地保存了抗原性。与传统的各种免疫组化技术比较,切片的各部分组织均能迅速与抗体反应,组织保存相当完好,可以满足电镜观察的要求。运用这种方法,还可以将同一胚胎的不同切片分别用于光镜和电镜观察,使结果更具说服力。     

Evidence of increased endometrial vascular permeability at the time of implantation in the short-nosed fruit bat, Cyanopterus sphinx

Early embryonic development and implantation were studied in tropical short-nosed fruit bat Cyanopterus sphinx. We report preimplantation development and embryo implantation. Different stages of cleavage were observed in embryo by direct microscopic examination of fresh embryos after retrieving them either from the oviduct or the uterus at different days, up to the day of implantation. Generally, the embryos enter the uterus at the 8-cell stage. Embryonic development continued without any delay and blastocyst were formed showing attachment to the uterine epithelium at the mesometrial side of the uterus. A distinct blue band was formed in the uterus. The site of blastocyst attachment was visualized as a blue band following intravenous injection of pontamine blue. Implantation occurred 9+/-0.7 days after mating. This study reports that bat embryonic development can be studied like other laboratory animals and that this bat shows blue dye reaction, indicating the site and exact time of implantation. This blue dye reaction can be used to accurately find post-implantational delay. We prove conclusively that this species of tropical bat does not have any type of embryonic diapause.     

Activity of embryonic mink genome during diapause (cytogenetic analysis): nucleolar and extranucleolar rna synthesis

The nucleolar and extranucleolar RNA synthesis was studied in the mink blastocysts at different stages of embryonic diapause and during the periimplantation period using cytoradioautography. The data obtained suggest a differential and stage specific activity of the embryonic mRNA and rRNA synthesis during the period of delayed implantation.     

Activity of Embryonic Mink Genome during Diapause (Cytogenetic Analysis): Nucleolar and Extranucleolar RNA Synthesis

The nucleolar and extranucleolar RNA synthesis was studied in the mink blastocysts at different stages of embryonic diapause and during the periimplantation period using cytoradioautography. The data obtained suggest a differential and stage specific activity of the embryonic mRNA and rRNA synthesis during the period of delayed implantation.     

Caveolin-1在围植入期小鼠子宫内膜组织中的动态变化

目的检测caveolin-1在胚胎植入过程中小鼠子宫内膜组织中的表达,探讨其在胚胎植入过程中的作用。方法选择成年雌性昆明小白鼠42只,随机均分为7组(处于动情期的未孕组、妊娠3.5天组、妊娠4.5天组、妊娠5.5天组、妊娠6.5天组、妊娠7.5天组、妊娠9天组),采用免疫组织化学和RT-PCR方法检测子宫内膜组织中caveolin-1蛋白及mRNA水平在围植入期的变化。结果 (1)caveolin-1在胚胎植入前期(0d、3.5d)小鼠子宫内膜组织中的表达高于胚胎植入期(4.5d、5.5d、6.5d),差异有显著性(P<0.05)。(2)caveolin-1在胚胎植入后期(7.5d、9d)小鼠子宫内膜组织中的表达高于胚胎植入期(4.5d、5.5d、6.5d),差异有显著性(P<0.05)。(3)caveolin-1在胚胎植入后期小鼠子宫内膜组织中的表达略高于胚胎植入前期,但差异无显著性(P>0.05)。结论 Caveolin-1在胚胎植入前期和后期均高表达,植入期低表达。这种变化提示caveolin-1是影响胚胎植入的重要因素之一。     

Collagen concentrations in dissected tissue compartments of rat uterus on days 6, 7 and 8 of pregnancy.

Implantation and non-implantation sites were dissected into myometrial and stromal components; a decidual/embryonic region was obtained on Days 7 and 8 of pregnancy. The concentration of collagen (as a percentage of the dry weight of tissue), measured by hydroxyproline analysis, was significantly lower in the implantation regions than in the non-implant regions in all areas studied. The concentrations in the antimesometrial myometrium and stroma of the implantation region remained the same over the days studied. In contrast, the mesometrial collagen concentration in the implantation region declined from Day 6 to Day 8 of pregnancy. Collagen concentration was low within the decidual/embryonic tissue on Days 7 and 8 of pregnancy. Remodelling of collagen within the embryonic area appears to be an important feature of the uterine response to implantation in rats.     

人胚胎干细胞向滋养层分化的研究进展

哺乳动物胚胎发育产生的第一个细胞系的分离是内细胞团和滋养层的分离,不同哺乳动物之间胚胎干细胞向滋养层细胞分化不同,滋养层细胞对胚胎的植入、促进胚胎在子宫内的生存和生长至关重要.人胚胎干细胞为研究人类胚胎发育及向滋养层分化提供了一个独特的模型.人胚胎干细胞可以在实验室条件下保持无限期稳定的培养,用于最初胚胎和滋养外胚层发生的机制研究.目前人胚胎干细胞分化为滋养层细胞在体外可以通过自发分化、基因敲除、分离EB小体和BMP4诱导等几种途径实现.不同哺乳动物之间胚胎干细胞向滋养层分化机制,主要通过信号通路如BMP4,LIF等以及某些标志基因如OCT4,CDX2,Eomes等的变化调节.人胚胎干细胞向滋养层分化的研究为临床应用提供了一定的基础.     

Cytogenetic study on the activity of the ferret embryonic genome before implantation

A cytogenetic study of the activity of the embryonic genome in ferret (Mustela putorius) blastocysts during ∼6 days after their transition from the oviduct to the uterus has been carried out. It has been found that the prolongation in the preimplantation period in the ferret is not accompanied by inhibition of mitosis or activity in nucleolus organizing regions of inner cell mass cells as occurs in species having an obligatory delay of implantation (obligate embryonic diapause). Amitosis of trophoblast cells starts at the periimplantation stage as in other species that do not have obligate diapause. The data obtained are consistent with the hypothesis that the obligatory stage of delayed implantation might occur in some mammals in different taxonomic groups as a result of chromosome mutations affecting the genetic control of the chronology of events (timing) of embryogenesis. Consequently the characteristics of delayed implantation should be different in different species.     

Cloning of leukemia inhibitory factor (LIF) and its expression in the uterus during embryonic diapause and implantation in the mink (Mustela vison)

Leukemia inhibitory factor (LIF) is essential for embryo implantation in mice. Whether LIF plays a role in termination of embryonic diapause and initiation of implantation in carnivores, especially in species with obligate delayed implantation such as the mink, is not known. The objectives of this study were to clone the LIF coding sequence in the mink and determine its mRNA abundance in the uterus through embryonic diapause, implantation, and early postimplantation. We show that the mink LIF cDNA contains 609 nt encoding a deduced protein of 203 amino acids. The homologies are 80.6, 90, 88.2, 87.6, and 86.8% in coding sequence and 79.2, 90.1, 91, 90.1 and 85.4% in amino acid sequence with mouse, human, pig, cow, and sheep respectively. Glycosylation sites and disulfide bonds present in other species are generally conserved in the mink LIF sequence. Quantitation by polymerase chain reaction amplification indicates that LIF mRNA is expressed in mink uterus just prior to implantation and during the first two days after implantation, but not during diapause or later after implantation pregnancy. The abundance of LIF mRNA was significantly higher in the uterus at the embryo expansion stage (P < 0.05) than at days 1–2 of postimplantation. By immunohistochemical localization it was shown that LIF is expressed in the uterine epithelial glands at time of embryonic expansion and in early postimplantation. The coincidence of LIF expression with implantation in this species suggests that LIF is involved in the implantation process, and may be a maternal signal which terminates obligate embryonic diapause. Mol. Reprod. Dev. 51:13–21, 1998. © 1998 Wiley-Liss, Inc.