中国大鲵肝脏的超微结构

应用透射电镜对中国大鲵的肝脏进行了超微结构研究.观察表明,大鲵肝不具肝小叶,与其他脊椎动物有所不同.肝细胞含有单个卵圆形的核;细胞质内含有粗面内质网、高尔基囊泡、线粒体、糖原颗粒和脂滴等细胞器和内含物.胆小管由两个相邻肝细胞质膜凹陷围成,而肝血窦则由内皮细胞的胞质构成.胆小管腔和窦周隙内浸润许多由肝细胞发出的微绒毛结构.还发现了枯否氏细胞和贮脂细胞.还讨论了中国大鲵肝脏的一般形态结构特点.     

不同生殖期鳜肝脏超微结构变化的观察

应用透射电镜对生殖季节与非生殖季节鳜肝脏超微结构的变化进行了观察。鳜肝细胞含有单个卵圆形的核,核仁清楚;细胞质内含有粗面内质网、线粒体、糖原颗粒和脂滴等细胞器和内含物。胆小管由相邻的数个肝细胞质膜凹陷围成,而肝血窦则由内皮细胞的胞质构成。还发现了贮脂细胞、枯否氏细胞和成纤维细胞。胆小管腔和窦周隙内浸润许多由肝细胞发出的微绒毛结构。鳜肝细胞的超微结构在产卵前后呈现明显变化：产卵前的肝细胞内富含线粒体、糖原颗粒和脂滴,粗面内质网发达;而产卵后的肝细胞内核仁发生迁移,部分细胞核囊泡化,糖原颗粒和脂滴排空,少数肝细胞具双核结构。非生殖期多数肝细胞核含有双核仁结构,胞质内溶酶体数量增多。     

乙型肝炎、肝硬变中一种小多角细胞的观察

我们曾在２６例肝硬变标本中发现一种小多角细胞－－肝小多角细胞（ＳＰＬＣ）,但其性质和来源仍不清。本研究在２６０例乙型肝炎、肝硬变组织中对ＳＰＬＣ的有无及其增生程度进行了观察,结果表明,急性肝炎中无ＳＰＬＣ,３７％的慢性迁延性肝炎、６４％的慢性活动性肝炎及６７％的肝硬变标本中均能见到ＳＰＬＣ,而且其数目随慢性肝脏病变的进展而逐渐增加。应用多种抗体进行的免疫组织化学染色表明,它们全为细胞角蛋白（ＣＫ）１８阳性,显示其上皮性质;界板附近的ＳＰＬＣ呈ＣＫ１９和Ｓ－１００蛋白阳性,提示它们具有增生胆小管上皮的某些表型;部分ＳＰＬＣＨＢｓＡＧ阳性,提示它们又有肝细胞的某些特点;多数ＳＰＬＣ表达胰岛素样生长因子（ＩＧＦⅡ）—一种癌胚性强致裂原,表明它们是一种幼稚细胞。我们认为,ＳＰＬＣ是一类兼有增生胆小管上皮和肝细胞性质的新型肝脏细胞,具有干细胞的性质,可能是上皮性于细胞向成熟肝细胞分化过程中的中间形态,其增生反映了非界板性肝细胞的大量损失。     

肝细胞极化的结构功能特征及在肝脏疾病时的病理表现

肝细胞极化的形成和维持是肝细胞发挥正常功能的保证。与简单极化上皮细胞不同,肝细胞在肝脏血管与胆小管间形成多个极化膜面,并由紧密连接分隔。极化肝细胞膜及细胞内骨架结构与功能复杂并有序,其分子组成及物质转运机制近年来已被逐渐认识。由于肝细胞极化与肝脏生理功能及多种肝脏疾病时的病理改变有着密切关系,该文就目前肝细胞极化分子和细胞水平研究现状进行综述,并探讨此领域研究发展方向。     

鳗鲡肝脏,脾脏显微与超微结构

经光镜和电镜观察发现：鳗鲡肝脏的肝小叶不规则。肝细胞胞质内翕含多种细胞器及包含和,胆小管由２－４个肝细胞围成,相邻肝细胞间有连接复合体封闭胆小管。血窦为有孔型,孔处无隔膜,内有巨噬细胞。窦周隙明显,未见贮脂细胞。肝猾胆小管腔与窦周隙面伸出许多指状微绒毛。脾脏内白髓中淋巴细胞聚集成群,无未见明显脾小结,淋巴鞘,红髓由脾索与脾窦组成,动脉分支末端（壁厚的毛细血管）可开放于红髓,无明显巨噬细胞中心,脾窦     

鳗鲡肝脏、脾脏显微与超微结构

经光镜和电镜观察发现：鳗鲡肝脏的肝小叶不规则。肝细胞胞质内富含多种细胞器及包含物。胆小管由２—４个肝细胞围成，相邻肝细胞间有连接复合体封闭胆小管。肝血窦为有孔型、孔处无隔膜，内有巨噬细胞。窦周隙明显，未见贮脂细胞。肝细胞向胆小管腔与窦周隙面伸出许多指状微绒毛。脾脏内白髓中淋巴细胞聚集成群，未见明显脾小结、淋巴鞘。红髓由脾索与脾窦组成，动脉分支末端（壁厚的毛细血管）可开放于红髓，无明显巨噬细胞中心。脾窦及脾小动脉内皮细胞通常为长杆状、沿血管纵向平行排列。脾窦为有孔型，孔处可见薄的隔膜。脾小动脉内皮外为２—５层平滑肌（多数为纵行）。     

体外诱导骨髓间充质干细胞向肝细胞分化的研究

肝脏是体内最重要、最复杂的器官之一,是机体物质代谢的核心,具有生物分化和免疫等重要功能;同时,肝脏也是一个极易受损伤的器官,病毒、肿瘤等会导致肝脏功能的缺损甚至累及生命;而随着肝移植技术的发展,肝细胞移植有望成为治疗肝功能衰竭的一种新方法。干细胞是一类具有自我更新、增殖和分化能力,特别是具有向肝脏干细胞、肝细胞及血管内皮细胞分化潜能的一类细胞,因而干细胞有望成为肝组织工程新的种子细胞来源。因此,本文对骨髓间充质干细胞的分离、培养,定向诱导肝细胞的影响因素以及应用前景等几方面的内容进行了总结。     

稀土元素铈铕钆铽在小鼠肝脏中的分布与沉积的电镜与X射线微区分析术研究

本实验分别给小鼠腹腔与静脉隔日交替注射稀土元素化合物氯化铈、氯化铕、硝酸钆、葡萄糖酸铽,共五次,总剂量为300～630mg/kg。电镜观察显示,四种元素均于枯否细胞和肝细胞中形成凝集体,枯否细胞中尤多。应用X射线微区分析术于凝集体分别探测到四种稀土元素的特征性X射线能谱峰。两种细胞的溶酶体内含较多高电子密度微粒。于胆小管腔亦发现高电子密度微粒群,提示肝细胞中的稀土元素可随胆汁排出。本文描述了四种稀土元素引起的肝脏形态学变化。     

钐在小鼠肝脏细胞中的动态观察

本实验给小鼠一次静脉注射氯化钐(70mg/kg体重)后15min至48h中的不同间期,应用电镜与X射线微区分析术对钐在肝脏枯否细胞与肝细胞中的运转进行了动态追踪。于15min 至2 h,两种细胞均以胞吞方式摄入含钐微粒,在胞质中形成吞噬体。在吞噬体中,微粒群处于由稀疏至密集的浓缩过程。小吞噬体亦互相融合。这种胞吞作用于枯否细胞极为活跃。于4—24 h,很多枯否细胞胞质充满吞噬体,细胞已经或趋于变性、崩解。肝细胞内的吞噬体则汇集于胆小管周围。于胆小管腔中可见到高电子密度微粒群,表明体内钐可经胆汁途径排出。于48 h,两种肝脏细胞巾仍见钐吞噬体沉积。     

肝缺血再灌流损伤和复方丹参保护作用的实验研究

观察大鼠肝脏缺血后再灌流时酶组织化学及超微结构的变化,同时观察复方丹参的保护作用。结果显示：肝缺血２小时后再灌流３小时,肝ＳＤＨ、Ｍｇ２＋－ＡＴＰａｓｅ、Ｇ－６－Ｐａｓｅ的活性明显降低,ＬＤＨ、ＡＣＰ的活性明显增强。超微结构变化表现为肝细胞内线粒体肿胀、嵴断裂、空泡样变,粗面内质网颗粒明显减少,肝窦扩大、窦壁内皮细胞肿胀,胆小管扩张,微绒毛减少、断裂。复方丹参对肝细胞的缺血再灌流损伤有明显的保护作用     

不同月龄虹鳟肝显微及超微结构特征

应用多种组织化学方法和透射电镜技术,对同一生长条件下8月龄、20月龄及30月龄虹鳟（Oncorhynchus mykiss）肝显微结构和超微结构特征进行研究。结果表明：不同月龄虹鳟肝被膜均为单层扁平上皮,厚度变化明显;肝细胞为单核,8月龄细胞排列不明显,20月龄及30月龄形成完整双层管式排列,胆管及其周围结缔组织随月龄发育尤为明显,血窦分支吻合成网状,窦壁内皮细胞扁平,胞质孔较多,窦腔内巨噬细胞具有典型胞质突,但并没有观察到Kupffer细胞;各月龄组肝星状细胞发育完善,胞突彼此相连;汇管区分为胆管孤管型、胆管动脉型、胆管静脉型、胆管动静脉型4种,8月龄以胆管孤管型为主,20月龄以胆管动脉型为主,30月龄以胆管动脉型、胆管动脉静脉型为主。因此,性成熟前虹鳟肝组织结构与其生理发育密切相关,胆管系统结构形式随月龄变化明显,肝细胞排列逐渐完善,Disse间隙胶原纤维及网状纤维含量逐渐增加,与被膜、中央静脉及汇管区结缔组织互相延伸,构成肝完整骨架,有利于调节肝细胞正常生理功能。     

Scanning electron microscopy of normal rat liver: the surface structure of its cells and tissue components.

Scanning electron microscopy (SEM) allows the surface ultrastructure of intrahepatic cells and other tissue components of liver to be delineated. Excellent depth of focus of the SEM makes it possible to visualize surfaces of intact cells in their native configurations. This report details the surface characteristics and inter-relationships of hepatocytes and hepatic plates, sinusoidal endothelial cells and sinusoids, presumed Kupffer cells, vessels, bile ducts, connective tissue, and the capsule of rat liver. Hepatocytes present three structurally distinctive faces--the intercellular face containing flat surfaces and bile canaliculus, the sinusoidal face, and the connective tissue face which abuts portal tracts and hepatic veins. Sinusoidal endothelium is penetrated by large (1 to 3 mum) and small (0.1 mum) fenestrae, the latter occurring in clusters of up to 50. The width of bile canaliculi and distribution of large fenestrae vary proximodistally along hepatic plate or sinusoid. The cells of portal bile ductules contain microvilli located in linear rows and sparse cilia. Endothelium of hepatic artery and of portal vein is sparsely fenestrated.     

Analysis of the sinusoidal endothelial cell organization during the developmental stage of the fetal rat liver using a sinusoidal endothelial cell specific antibody, SE-1

The sinusoid organization during the development of fetal rat livers was studied using a SE-1 antibody, which we have previously established as a specific monoclonal antibody against rat sinusoidal endothelial cell (SEC). Expression and localization of the SE-1 antigen in the liver tissues of 13- to 21-day-old fetuses were immunofluorescently and immunoelectron microscopically examined. The first positive fluorescence was observed in the immature liver of 15-day-old fetuses. The initial positive staining was randomly distributed in the liver parenchyma and showed no direct relation to the large vessels which may be derived from the fetal vitelline veins. The positive linear staining increased in number and connected with each other during the course of development. The SE-1 staining pattern and the sinusoidal arrangement became similar to those of the adult liver after 20th day of gestation. Immunoelectron microscopically, the immature SEC showed a weak positive reaction for the SE-1 antigen at their membrane and was observed together with immature hepatocytes and hematopoietic cells in the 15-day-old fetal liver. Along with the liver development, SEC formed a sinusoid structure closely associated with hepatocytes and came to strongly express the SE-1 antigen. These results indicate that the organization of the hepatic sinusoid may start at around 15th day of the gestation and occurs randomly in the fetal liver parenchyma. It is also suggested that the expression of SE-1 antigen is possibly regulated by the intimate association with hepatocytes.     

大鼠肝脏水通道蛋白7的表达

目的研究水通道蛋白7(AQP7)在大鼠肝脏中的表达和分布。方法选用成年健康SD大鼠,采用免疫组织化学的方法对肝脏中AQP7蛋白的表达进行定位检测。结果AQP7阳性免疫反应产物集中位于大鼠肝脏毛细胆管面的肝细胞质膜上,肝细胞的基膜面和血窦面未见阳性免疫反应产物。结论AQP7在肝脏中的表达及其空间上的分布提示其可能参与胆汁的分泌。     

Ultrastructural changes in rat livers perfused in vitro and in vivo with a high dose of methotrexate

Methotrexate is an antifolate that is widely used in the treatment of malignant tumours and other diseases. The present study was undertaken to examine the short-term effects of high doses of methotrexate (HD-MTX) on the ultrastructure and metabolic activity of isolated rat livers. The authenticity of the drug-induced changes was substantiated by the concomitant use of in vivo experiments. Isolated rat livers were infused with HD-MTX via the portal vein for 3 hours (total dose for each liver 2000 mg). For in vivo experiments, each rat received a single intravenous injection of a maximum tolerated dose of MTX (100 mg/kg body weight) that allowed the animals to survive for 3 days. At the end of each experimental period, MTX-treated and control livers were processed for light microscopy (LM), scanning (SEM) and transmission electron (TEM) microscopy. Oxygen consumption and thyroxine metabolism were measured in treated and control isolated livers. With the exception of a few minor differences, the structural changes in the hepatocytes after MTX treatment in vitro and vivo were similar. There were focal changes consisting of disruption of normal hepatic plates and swelling and vacuolation of the hepatocytes, with no clear evidence of restriction to a specific hepatic zone. SEM revealed striking changes in the plasma membrane, the microvillar system, intercellular junctions and the sinusoidal endothelium. TEM revealed disorganized endoplasmic reticulum, dispersion of the polyribosomes, a variety of mitochondrial changes, and glycogen redistribution. In MTX-treated isolated rat livers, the uptake of tetraiodothyronine (T4) was not affected, but triiodothyronine (T3) release was impaired. Oxygen consumption was increased in livers treated with MTX. Employing an organotypic liver perfusion model in conjunction with the in vivo experiment and the use of SEM, TEM and hepatic thyroxine measurements, this investigation revealed that infusion of HD-MTX induced early ultrastructual changes in cell membrane, intercellular junctions and cell organelles and disturbance in the functional integrity of the hepatocytes in isolated rat liver.     

A new technique for primary hepatocyte expansion in vitro

The current application for many potential cell-based treatments for liver failure is limited by the low availability of mature functional hepatocytes. Although adult hepatocytes have a remarkable ability to proliferate in vivo, attempts to proliferate adult hepatocytes in vitro have been less successful. In this study, we investigated the effect of coculture cell type on the proliferative response and the functional activities of hepatocytes. We show, for the first time, a robust proliferative response of primary adult rat hepatocytes when cocultured with mouse 3T3-J2 fibroblasts. Hepatocytes cultured at low density on growth-arrested 3T3-J2 fibroblast feeder layers underwent significantly higher proliferation rates than when cultured on feeder layers made of four other cell types. Increasing colony size correlated with an increase in hepatocellular functions. The proliferating hepatocytes retained their morphologic, phenotypic, and functional characteristics. Using a cell patterning technique, we found that 3T3-J2 fibroblasts stimulate DNA synthesis in hepatocytes by short-range heterotypic cell-cell interactions. When hepatocytes that proliferated in cocultures were harvested and further subcultured either on 3T3-J2 fibroblast feeders or in the collagen sandwich configuration, their behavior was similar to that of freshly isolated hepatocytes. We conclude that adult rat hepatocytes can proliferate in vitro in a coculture cell type-dependent manner, and can be serially propagated by coculturing with 3T3-J2 fibroblasts while maintaining their differentiated characteristics. Our results also suggest that one of the major reasons for the functional differences in hepatocyte cocultures may be due to the different proliferative responses of hepatocytes as a function of coculture cell type. This study provides new insights in the roles of coculture cell types and cell-cell interactions in the modulation of hepatic proliferation and function.     

Ultrastructural zonal heterogeneity of hepatocytes and mitochondria within the hepatic acinus during liver regeneration after partial hepatectomy

BACKGROUND INFORMATION: Partial hepatectomy (70%) induces cell proliferation until the original mass of the liver is restored. In the first 24 h after partial hepatectomy, drastic changes in the metabolism of the remaining liver have been shown to occur. To evaluate changes in hepatocyte ultrastructure within the hepatic acinus during the liver regenerative process, we investigated, by light and electron microscopy observations on specimens taken 0 h, 24 h and 96 h after partial hepatectomy, the hepatocyte structure and ultrastructure in the periportal and pericentral area of the hepatic acinus, with a particular emphasis on mitochondria ultrastructure. Moreover, some biochemical events that could affect the mitochondria ultrastructure and function were investigated. RESULTS: We found that, 24 h after partial hepatectomy, mitochondria with altered ultrastructure were preferentially localized in the periportal area. Periportal hepatocytes showed also an increase in the number of peroxisomes, free ribosomes, lysosomes and autophagosomes. Altered mitochondria showed swelling, an ultrastructural index of increased membrane permeability, a reduction in the number of cristae, and a rarefied, often vacuoled, matrix. Consistently, an increase in the mitochondrial oxidized/reduced glutathione ratio was found as well as calcium release from mitochondria in a manner inhibited by cyclosporin A. Interestingly, light and electron microscopy analysis showed that the hepatocytes in the periportal area were the cells with the major structural attributes to proliferate. At 96 h after partial hepatectomy, the preferential zonation of altered mitochondria was lost and the normal mitochondrial membrane permeability properties were restored. CONCLUSIONS: We suggest that 24 h after partial hepatectomy, a preferential zonation of altered mitochondria in the periportal hepatocytes could be involved in the changes of metabolic and functional heterogeneity of the hepatocytes within the hepatic acinus during the regenerative process.