关于有尾类非典型胚胎表皮的传导能力

庄和戴在蝾螈胚胎的联体—正常胚胎和割除神经板的胚胎前后地接到一起—观察到刺激表皮可以引起躯体运动反应;用黑斑蛙的胚胎得到一致的结果,因此肯定地证实了Wintrebert发现的、而后有争议的两栖类胚胎表皮传导刺激的能力。范和戴用微电极记录了伴同传导的电活动。Roberts Roberts和Stirling用     

影响有尾类离体胚胎表皮细胞兴奋性的实验

It has been reported that in Cynops orientalis the cells in the atypical epidermis resulted from isolation of the ectoderm from the early gastrula and cultured in vitro possesses very low excitability. The great majority of the explants didn't display action potential (AP) with electric stimulus up to 6 V duration 1 ms). If, however, the epidermis was taken from the flank region of a neurula with the underlying mesoderm, in such explant the epidermis cells became excitable at a lower threshold of stimulus. The mesoderm seemed to exert some influence upon the epidermis. In order to study whether tissues other than mesoderm possess similar effect on the excitability of epidermis cells, different combinations of explants were made with the experimental embryological technique and their excitability was examined electrophysiologically. In all experiments the explants were stimulated extracellularly and the action potential was recorded intracellularly. The specimens were stimulated with electric stimulus at 6 V at first, and, if they displayed AP the strength was lowered to determine the threshold of stimulus to evoke AP. The duration of stimulus was fixed at 1 ms. For the control of all series, the ectoderm or epidermis was isolated at the same stage and cultured for the same length of period as the experimental explants but without any treatment. 1). The effect of calf serum. In this group the effect of calf serum was examined and following series were carried out: a) Gastrula ectoderm cultured in Holtfreter solution containing 10% calf serum; b) calf serum + agar as implant: calf serum was mixed with agar (1:1) and cut into small pieces when cooled, and the serum + agar pieces were wrapped with ectoderm; c) heated serum + agar, heated serum was mixed 1:1 with agar and the small pieces were wrapped with ectoderm. In all the experiments the excitability of the epidermis cells was raised more or less but the agar pieces containing fresh serum seemed to be more effective, perhaps due to the higher concentration of the serum and the intimate contact with the epidermis cells (Tab. 1) In the series with serum + agar as implant and in the series with heated serum + agar as implant, it occurred frequently that during cultivation the implants will be extruded and after the extrusion of the implant the remaining epidermis became less sensitive to stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)     

代谢抑制剂对有尾类胚胎表皮细胞兴奋性的影响

It has been reported that the cells in atypical epidermis, which developed from the in vitro cultured ectoderm isolated at early gastrula, showed very low excitability or were even non-excitable at 6 V when examined electro-physiologically. If non-excitable explants were treated with energy supplying substances, such as glucose, the action potential (AP) appeared quickly. It indicates that, the excitability of epidermis cells is related to their energy metabolism. In order to verify the above proposition the effects of metabolic inhibitors on the excitability of the epidermis cells were examined using electrophysiological technique. Two kinds of explants were used: explants which developed from the epidermis underlaid with mesoderm isolated at early neurula (epidermis vesicle) and explant which developed from the ectoderm isolated at early gastrula (atypical epidermis). In all experiments explants were stimulated extracellularly and APs were recorded intracellularly. The specimens were stimulated with electric stimulus at 6 V first, and, if they displayed AP, the strength was lowered to determine the stimulus threshold to evoke AP. The duration of stimulus was fixed at 1 ms. The ratio of the resting potential value during treatment to the original value was taken as index of change level of the resting potential (RP). During treatment of epidermis vesicle with 1 mM NaN3 or 1 mM NaCN or 0.1 mM 2,4-dinitrophenol (DNP), the excitability of the epidermis cells was reduced: the stimulus threshold gradually increased and the cells in most explants lost the excitability. The cells became excitable after the drugs were washed out.(ABSTRACT TRUNCATED AT 250 WORDS)     

影响有尾类离体胚胎表皮细胞兴奋性的实验

用常规电生理细胞内记录技术了解了影响蝾螈胚胎非典型表皮细胞兴奋性的一些因素。1.小牛血清、蝾螈胚胎内胚层和肌节中胚层、非洲爪蟾胚胎外胚层及嫁接于受体胚胎都提高非典型表皮显示动作电位样品的百分比。血清琼脂包饺子的作用较培养在含血清溶液明显。内、外胚层的作用更为明显。嫁接于受体胚胎的非典型表皮百分之百地显示兴奋性。2.血清、内、中、外胚层及嫁接于受体胚胎都降低表皮细胞的刺激阈值。各处理组的平均阈值均低于对照组,其巾嫁接于受体胚胎的非典型表皮细胞最低,接近于正常胚胎的表皮细胞。3.血清琼脂块和内胚层包饺子的实验表明,影响兴奋性的因素必须始终与表皮细胞保持接触,才‘能产生作用。一旦脱离接触,其作用就逐渐消失。4.胚胎表皮细胞兴奋性的产生不依赖于外来因素,是一种自主的功能分化。但是外来因素能使培养的表皮细胞的兴奋性增强,对低强度的刺激产生兴奋。这种外来因素可能是一些非专一性的与代谢有关的物质。     

代谢抑制剂对有尾类胚胎表皮细胞兴奋性的影响

离体培养的蝾螈胚胎的非典型表皮,其中的大部分在较高强度的电刺激下细胞不显示兴奋性,少量显示兴奋性的外植块所需的刺激强度也高于正常胚胎表皮。用含有能量物质(碳水化合物、氨基酸、代谢中间产物和ATP)的     

中胚层在有尾类胚胎表皮传导中的作用(简报)

从前我们报道过,从蝾螈的早期原肠胚分离培养的非典型表皮,对电刺激不产生可传播的兴奋,但是嫁接到受体胚胎则成为可能产生可传播的兴奋,并能将冲动传到后者,说明兴奋性的产生不单纯是细胞分化的后果,而是受到其它因素的影响。曾经推断这种因素可能是一种物质。根据非典型表皮与受体胚胎在嫁接中接触的情况,尤其是来自中胚层的物质可能和表皮细胞产生传导能力有密切关系。     

用异龄移植研究有尾类胚胎表皮传导能力的出现和消失

两栖类胚胎的表皮,只是在一定的发育阶段具有传播兴奋的能力。有尾类胚胎表皮显示可兴奋性的期间,从分期26(早尾芽期)开始,直到分期37末(第一对外鳃出现分枝),某些部位甚至更晚些。无尾类的爪蟾和黑斑蛙胚胎,虽然其体形以及以此为准的分期与蝾螈的有所不同,表皮传播兴奋的期间,自分期24到分期40,和后者基本一致。     

蝾螈胚胎表皮兴奋性在发育中的变化

1.蝾螈胚胎表皮在分期26动作电位刚出现时,同一胚胎不同部位表皮细胞的兴奋性不同,存在一个沿头—尾轴的梯度变化。头部细胞引起动作电位所需的阈值??最低,即细胞兴奋性最强。尾部所需阈值最高,中部在两者之间。这一梯度在分期26末消失。2.胚胎在整个传导期间(分期26至分期37),表皮细胞兴奋性也不是恒定的,呈低一高一低的变化过程。在分期32,阈值线达最低值,即此时表皮细胞最容易兴奋。3.在胚胎表皮动作电位消失过程中表皮细胞兴奋性存在一个与动作电位出现时相反的梯度。不仅头一尾、而且背、腹也存在这种兴奋性梯度。背面头部动作电位最早消失,腹面尾部可维持到分期38中期。4.表皮细胞兴奋性出现时,动作电位有一个发生、发展的过程。离体实验表明,含有头部中胚层的表皮,动作电位的出现早于含有尾部中胚层的表皮,平均早出现2.4小时。这说明表皮兴奋性按时空顺序出现可能受到其下不同部位中胚层的某些影响。5.离体实验还提出了神经嵴对表皮兴奋性的出现也有一定影响,虽然作用似乎比中胚层要弱一些。     

蝾螈胚胎表皮兴奋性和传导能力的出现和消失

两栖纲中有尾目和无尾目胚胎表皮在一定发育阶段都具有兴奋性并能传导兴奋的问题,经过一番争论之后终于被肯定了下来。有尾目中蝾螈的胚胎在发育分期26阶段出现前肾隆起时,表皮出现兴奋性和传导能力;但这时胚胎的肌肉还处于不具有收缩能力的时期。胚胎表皮的兴奋性和传导能力一直维持到分期37。至于     

蝾螈胚胎表皮细胞膜的静息电位,输入电阻与其兴奋性的关系

用微电极细胞内记录技术研究了东方蝾螈胚胎表皮细胞膜的静电位、输入电阻与其兴奋性的关系,在兴奋性形成期间正常胚胎表皮细胞的静息膜电位逐渐增大,膜的输入电阻逐渐减小。与不显示兴奋性的离体非典型胚胎表皮细胞相比,显示兴奋性的膜电位较高,膜电阻较低。用葡萄糖处理非典型表皮,在兴奋性出现同时,细胞膜超极化,膜电阻减小。用哇巴因处理表皮囊泡,在兴奋性消失同时,细胞膜去极化。结果表明,细胞能量供应不足所造成的膜     

东方蝾螈早期发育过程中细胞核超微结构的观察

东方蝾螈胚胎发育过程中,从原肠早期到原肠末期无论外胚层或中胚层细胞核内都含有大量的异染色质团块,而到神经板形成后所有细胞核内染色质均呈分散状态。异染色质向常染色质的转变过程发生在原肠末期到神经板形成这段时间里,在原口闭合后4.5小时之前完成,此时期似乎是形态发生的转折点。到发育的后期,细胞核内有一些染色质又会由分散状态转变为凝聚的异染色质团块。预定神经上皮向神经组织分化的决定是个逐渐的过程,这一过程在原肠口闭合时已经开始,到神经板期完成。染色质的分散似乎发生在细胞有了初步决定之后。本文就染色质超微结构变化的意义以及染色质超微结构变化与细胞分化的关系等问题进行了讨论。     

东方蝾螈(Cynops orientalis)灯刷染色体的工作图谱

自Gall(1954)采用直接从卵母细胞胚泡取得灯刷染色体进行活体观察方法以来,对许多动物,特别是两栖类动物的灯刷染色体作了详细的研究和比较,并作出了一些工作图谱(working map)。为了在东方蝾螈(Cynops orientalis)开展工作,我们研究了它们的灯刷染色体的形态,并据此绘出了工作图谱。     

维生素A酸在东方蝾螈肢体再生过程中的出现和分布~*(简报)

有尾两栖类(蝾螈和美西螈)是脊椎功物中仅有的具备再生出失去肢体能力的动物。维生素A 酸(Retinoic Acid,简称RA)存在于鸡的发育中的肢芽,局部使用可模拟极化区的作用,因而被认为可能是形态发生素。作为     

东方蝾螈原肠形成期瓶状细胞的结构及其对胚胎发育的影响

以１００只东方蝾螈早期胚胎为材料,用ＳＥＭ和ＴＥＭ对瓶状细胞形态结构和除去瓶状细胞的胚胎进行观察,去除瓶状细胞后,胚胎的原肠形成不会中断,外包和内卷仍能正常进行,并可以发育成幼螈,但有部分胚胎原肠前端缺失,长期培养的蝾螈胚对针刺激有反应,幼虫阶段中自由活动,我们的结论是：１）东方蝾螈原肠胚的瓶状细胞除了原肠前端存在外,还有部分瓶状细胞与原肠长轴垂直,从力学角度推断瓶状细胞在原肠形成过程中不起主要作     

NPY样免疫反应在蝾螈发育过程中神经系统的定位研究

用免疫组化方法研究在蝾螈胚胎发育中神经肽Y(NPY)在神经系统中的定位.结果表明NPY最早分布在周边神经系统(尾芽晚期),之后才在中枢神经系统出现(幼虫期),而且是随着胶质细胞的出现而出现的.我们认为NPY是随着神经嵴细胞的迁移而进入周边神经系统,再分布到中枢神经系统的.     

东方蝾螈胚胎表皮细胞动作电位的离子依赖性

两栖类胚胎表皮细胞在其发育的一定阶段是可兴奋的,能传导兴奋,并伴有类似心肌细胞的动作电位。Sato等报道,蝾螈表皮细胞动作电位由两种成分组成:心肌型的慢电位和在这之前一个短时程的快电位。慢电位可以传递到其它细胞,而快电位是不传递的。他们认为,慢电位是由快电位诱导产生的。在我们以往的实验中,刺激和记录的不是同一个细胞,可能是由于快电位不能传递到被记录的细