Starvation induces the formation of giant mitochondria in gastric parietal cells of guinea pigs

Mitochondria occasionally increase in size in response to metabolic injury. Numerous studies have reported giant mitochondria in patients with various diseases and animals with metabolic injuries, but there are few reports on giant mitochondria in normal cells under physiological conditions. Here, we report giant mitochondria in normal gastric parietal cells. Stomachs of guinea pigs fed freely, fasted or fasted and then injected with histamine were processed for electron microscopy. Giant mitochondria >2 microm in the diameter of their major axis were observed in resting-type parietal cells in the gastric glands of animals fasted for 60-72 h, whereas acid-secreting-type parietal cells found in those fed ad libitum did not contain giant mitochondria. Giant mitochondria showed unusual structures, especially in their cristae: they contained closely packed, tubular and concentric cristae as well as amorphous and pleomorphic inclusion bodies in their matrix. We observed giant mitochondria consisting of several segments, suggesting the fusion of several normal-sized mitochondria. Histamine injection decreased in a frequency of giant mitochondria in accordance with a decrease in a frequency of resting-type parietal cells. This is the first report of giant mitochondria in gastric parietal cells under physiological or near physiological conditions. Gastric parietal cells might be a good model for examining mitochondrial fusion and fission in a physiological state accompanied by the morphological change of the cells in the membrane system from an acid-secreting to resting type.     

毒黄素对小鼠肾脏毒性作用的超微病理观察

观察毒黄素对小鼠肾脏的超微病理改变,探讨毒黄素中毒的机理。小鼠腹腔注射毒黄素（1.5 mg/kg）,2 h后取其肾皮质,应用电子显微镜观察其超微结构改变。电镜下可查见毒黄素主要损伤肾近曲小管上皮细胞的线粒体和毛细血管内皮细胞基底膜,表现为大量线粒体空泡化和毛细血管基底膜不匀性增厚。毒黄素可造成肾近曲小管上皮细胞和肾小球毛细血管内皮细胞的超微结构损伤,以线粒体和基底膜的损伤更为突出,为毒黄素的毒性作用提供超微形态学依据。     

利用快速共聚焦显微镜观察花粉管中线粒体的分布及其动态变化

线粒体是真核细胞中高度动态变化的一种细胞器。但目前有关植物细胞,尤其是花粉管中线粒体的分布及其动态变化的信息还比较少。本文应用Zeiss 5 live快速共聚焦显微镜结合线粒体荧光探针Mitotracker Green对百合花粉管中线粒体的分布及其动态变化进行了观察和测定。结果显示,正常培养的百合花粉管中线粒体呈倒喷泉式移动,即花粉管基部的线粒体移动到亚顶端后即发生回流,因此花粉管顶端锥形区域内很少观察到线粒体的存在。对单个线粒体进行跟踪分析结果表明花粉管中的线粒体分为快速运动和锚定状态两种。快速移动的线粒体在花粉管两侧质膜下及花粉管中央沿着与花粉管长轴平行的方向运动,在花粉管亚顶端则沿着一定曲线移动;锚定在细胞质中的线粒体则随着胞质环流而被动移动。低浓度的微丝骨架抑制剂Jas处理时间依赖性地引起花粉管亚顶端的线粒体逐渐前移,并最终充满整个花粉管顶端,同时花粉管中快速移动线粒体的比例逐渐减少。上述结果表明,花粉管中的线粒体主要沿着微丝骨架进行快速移动,而花粉管亚顶端精细微丝组成的领区(Collar)在花粉管线粒体的分布和动态变化中起重要作用。     

Correlative light and electron microscopic observations on ectopic neurons in the cerebellum of dreher mutant mouse

The structure of ectopic neurons in the cerebellum of dreher mutant mouse was investigated by correlative light and electron microscopic observations. Tissue blocks were fixed in buffered aldehyde and embedded in a mixture of 2-hydroxypropyl methacrylate, Quetol 523, and methyl methacrylate. Sections at 0.4-0.5 microns in thickness were examined by electron microscopy after observation under a light microscope. By comparing the electron images with those of light microscopy in the same sites, the structures of ectopic cells were confirmed. Ectopic Purkinje cells were arranged with cell bodies that contained an oval, spherical or wrinkled nucleus without deep invagination and the thin layers of endoplasmic reticulum at the perinuclear regions. Granule cells were ectopically matured in the external granular layer and within the cluster at the cortical region. This method provides a useful procedure for understanding structures of the cerebellar neurons of the mutant.     

Electron-microscopic observation of mouse spleen tissue infected with Orientia tsutsugamushi isolated from Shandong, China

Low-virulent Orientia tsutsugamushi (Ot) were successfully isolated from scrub typhus patients in Shandong, China, and the isolates were similar to the Kawasaki type identified by nested polymerase chain reaction (PCR). To identify the morphological characterization of the low-virulent Ot, and elucidate the pathological changes on host cells, mouse spleen tissue infected with the Ot isolated from Shandong was used for the ultrastructural study. Transmission electron microscopy showed that the Ot parasitized in the spleen were different in size, shape and electron density and many significant changes occurred in cytoplasmic organelles of the inoculated mouse spleen cells. Swollen perinuclear cisterna was observed in the nuclear membranes of mononuclear cells and a multivesicular body was found in the intracytoplasm of the macrophage. In the phagosome of the macrophage, many Ot enveloped with an additional membrane were found to push the phagosomal membrane outward from inside. The results indicated that the low-virulent Ot and the spleen cells suffered various damages.     

Cytochrome c oxidase activity in preosteoclasts induced by experimental tooth movement

Cytochrome c oxidase activity was detected in preosteoclasts induced by experimental tooth movement. Mitochondria with reaction products of the enzyme in the inner membrane and outer compartment, which we classified as type 1 mitochondria, were observed in preosteoclasts. The number of type 1 mitochondria in the preosteoclasts, however, was distinctly fewer as compared with those in active osteoclasts described in our previous studies. Also, some of preosteoclasts adjacent to the bone surface contained more type 1 mitochondria than preosteoclasts separated from the bone surface. These results suggest that cytochrome c oxidase activity is closely related to functional differentiation of preosteoclasts, and additionally can be used as an indicator of functional differentiation from preosteoclast to osteoclast.     

Two types of the enlargement of mitochondria related to apoptosis: simple swelling and the formation of megamitochondria

Our recent finding that free radical-induced formation of megamitochondria (MG) is followed by apoptosis has prompted us to investigate the correlation between the MG formation and the swelling of mitochondria which is considered to play a key role in early stages of apoptotic processes of the cell. Mitochondria of rat hepatocytes or RL-34 cells and those isolated from rat livers became enlarged up to three times in their diameters when they were exposed to a hypotonic medium. MG induced in the liver of rats placed on a 1% hydrazine-diet for 4-5 days or those induced in the liver of mice placed on a 2% chloramphenicol (CP)-diet for 9-10 days were endowed with a dense matrix whereas those fed with the toxic diets for longer periods of time became enlarged further and their matrix became extremely pale indicating that MG in the latter animals became swollen secondarily. The membrane potential, the content of cytochrome c and the rate of the generation of reactive oxygen species (ROS) of MG in the former animals were almost unchanged compared to those of mitochondria in control animals whereas those of MG in the latter animals became distinctly decreased. These results may suggest that free radical-induced MG possibly cause apoptosis via their secondary swelling.     

Efficient and accurate analysis of mitochondrial morphology in a whole cell with a high-voltage electron microscopy

Mitochondria in all eukaryotes are essential organelles responsible for adenosine triphosphate synthesis, calcium homeostasis and steroidogenesis. Because the structure and distribution of mitochondria are highly diverse depending on their function and cellular conditions, it is important to develop a rapid and accurate method to assess their morphology. In this study, we visualize whole mitochondria in cultured cells using high-voltage electron microscopy (HVEM). Compared with conventional transmission electron microscopic approaches, the present method does not require thin sectioning and thus requires less time for image acquisition and processing. Furthermore, compared with fluorescence-based light microscopic approaches, our method provides more accurate size information. Thus, we propose that HVEM is a useful tool for rapid and accurate analysis of mitochondrial morphology and distribution in a cell.     

自噬小体膜来源的形态学分析

目的:从形态学角度探寻自噬小体形成过程中的膜来源及自噬小体的超微结构特征.方法:应用透射电镜技术整理分析本中心收到的用于自噬研究的细胞标本,对自噬发生不同阶段及疑似自噬小体结构的图片进行分析.结果:在细胞内发现众多自噬小体结构,内质网、线粒体、细胞核和高尔基体均可形成类似自噬小体结构.结论:细胞内多种膜结构可能都是自噬小体的膜来源.     

小麦颖果发育过程中韧皮部细胞的结构变化观察

利用光学显微镜、透射电镜和扫描电镜技术．对小麦颖果发育过程中韧皮部细胞的结构变化进行了系统观察。结果表明，开花后7d颖果还没有形成完全分化的维管束。开花后12d韧皮部可见明显的筛分子。每个维管束有大约40个左右的筛分子，它们呈半圆形分布于维管束外侧。开花后14～20d，筛分子内有较丰富的线粒体、P^-型质体和许多无定型丝状物，有些筛分子有珠光壁。筛分子有典型的伴胞，并形成SE／CC复合物结构。伴胞有稠密的胞质和核质。韧皮薄壁细胞与中间细胞间有丰富的胞间连丝；韧皮薄壁细胞间的胞间连丝呈区域集中分布。开花后24-29d，筛分子内线粒体数目减少，伴胞和韧皮薄壁细胞电子染色变浅，说明它们的养分运输能力下降。中间细胞的细胞质内仍有丰富的线粒体和其它细胞器，它们沿胞壁周缘分布；此时，中间细胞形成类似筛分子的结构．因此中间细胞是一种适应于养分运输的特化伴胞，在颖果灌浆后期起重要作用。开花后39d，韧皮部细胞衰老变形，此时颖果发育成熟。     

空心莲子草对钉螺神经节及足肌超微结构的影响

研究空心莲子草（Alternanthera philoxeroides）杀灭钉螺的作用机理。将空心莲子草水浸液（1g／100ml）及去氯水分别浸泡钉螺24h后，用透射电镜观察两组钉螺神经节及足肌超微结构的变化。结果显示：钉螺经空心莲子草水浸液浸泡24h后，神经节细胞明显破坏，其细胞膜消失，细胞核固缩，胞质内细胞器变性坏死，次级溶酶体增多，神经纤维断裂；足肌纤维内细胞核肿胀，肌丝排列紊乱甚至溶解，细胞间隙明显增宽。结果提示：空心莲子草水浸液对钉螺神经节细胞有明显破坏作用，同时可引起足肌细胞变性及细胞间隙水肿。     

米酵菌酸对小鼠肝和心肌细胞毒性作用的超微结构研究

目的：观察米酵菌酸对小鼠肝、心肌细胞毒性作用的超微结构改变，探讨米酵菌酸中毒的机理，方法：小鼠腹腔注射不同剂量的米酵菌酸，2h后取其肝和心肌组织，通过电镜观察其细胞超微结构的改变，结果：电镜下可见肝细胞和心肌细胞的线粒肿胀，内嵴断裂，模糊或消失，基质局部或全部空亮，呈囊泡样变，偶见其中含髓样小体，上述线粒体内嵴和膜结构的病变随米酵菌酸剂量的增加而加重，结论：米酵菌酸对小鼠肝、心肌细胞毒性作用以线粒体的损伤较为突出，因此我们认为，线粒体内膜的破坏造成线粒体的功能障碍，影响细胞呼吸，使细胞缺氧导致小鼠中毒死亡。     

凋亡神经元线粒体超微结构的形态计量学分析

目的:观察并分析人大脑皮层凋亡神经元线粒体超微结构的形态计量学变化.方法:取21例脑外科手术患者的额叶大脑皮质超薄切片中的正常神经元和凋亡神经元的电镜照片各80张,分为对照组与凋亡组.采用形态计量学方法对两组神经元的细胞体、细胞核、线粒体及细胞质基质灰度进行分析.结果:与正常神经元相比,凋亡神经元线粒体的体密度、面密度、数密度、比膜面明显增大(P＜0.01),比表面无明显改变(P＞0.05),线粒体基质与细胞质基质灰度之差明显增大(P＜0.01).结论:凋亡神经元线粒体未发生明显肿胀或增生,但其内膜和嵴的面积明显增加,基质密度降低.     

An ultrastructural study on the effect of streptozotocin on the islets of Langerhans in mice

The ultrastructural changes in the morphology of the islets of Langerhans in response to streptozotocin were studied in the mice pancreas. Male white albino CSI mice were given a single intravenous injection of 75 mg kg(-1) body weight streptozotocin, and were sacrificed at different time intervals up to 48 h following the treatment. Their pancreases were excised and randomly processed for electron microscopic examination. Hyperglycaemia and glucosuria were detected 8 h after treatment, became remarkably high at 24 h and persisted then after. Light and electron microscopic examination of the islets of Langerhans from treated mice revealed an early chromatin aggregation and cytoplasmic vesiculation in the central B cells during the first 2 h of treatment. Nuclear shrinkage and pyknosis with swelling of mitochondria and endoplasmic reticulum were evident 8 h later, and lysis of B cells occurred 12 h after treatment. The morphology of A and D cells at the margin of the islets and in between B cell debris looked perfectly unaltered. Macrophage infiltration among lytic B cells was seen 24 h after drug administration, which contained clear and large phagocytic vacuoles. The necrobiotic and phagocytic figures disappeared from the pancreatic sections of 48 h treated mice, and the islets were smaller in size and consisted entirely of intact A and D cells with occasional degranulated B cells. No features of apoptosis were ever recorded, and the exocrine pancreatic tissue was protected from the effect of streptozotocin. In conclusion, the present study illustrates the sequence of morphological changes that occurs in the islets of Langerhans of mice after streptozotocin administration. It also confirms that streptozotocin at a high single dose in mice produces a specific necrosis of B cells with no evidence of apoptotic figures as another mechanism of cell death.     

肾上腺皮质腺瘤与嗜铬细胞瘤的电镜鉴别诊断

通过对3例肾上腺皮质腺瘤和3例嗜铬细胞瘤的光镜和电镜观察,分析了这两种肿瘤的超微结构特点及电镜在其鉴别诊断中的作用.提出了肾上腺皮质腺瘤与嗜铬细胞瘤的超微结构鉴别要点：①肾上腺皮质腺瘤瘤细胞胞质内的线粒体管泡状嵴,胞质中见大量拥挤的管状和泡状滑面内质网;②嗜铬细胞瘤含肾上腺素和去甲肾上腺素两种不同类型的神经内分泌颗粒,粗面内质网发达.同时讨论了线粒体管泡状嵴发生的机理.     

心肌细胞内SOD定位的电镜观察

利用心肌组织缺氧再灌注方法，已获得心肌细胞超氧化物歧化酶（ＳＯＤ）活性定位的证据，是通过Ｂｒｉｇｇｓ等人介绍的铈方法，用电子组化来研究的。羟基过氧化铈的形成作为ＳＯＤ活性的一种指示剂，其结果表明：（１）ＳＯＤ活性位置存在于心肌细胞浆基质及一些线粒体内，而细胞核及其它细胞器内未见同类标记物。（２）羟基过氧化铈可作为心肌细胞内ＳＯＤ的一种定位指示剂。     

与利它素分泌相关的桑蚕雌蛾性附腺超微结构研究

本文用扫描电镜和透射电镜对与野蚕黑卵蜂识别利它素分泌相关的桑蚕雌蛾性附腺分泌部进行了详细的研究。表明附腺分泌部中柱形腺上皮分泌细胞的超微结构与其功能具有非常好的一致性。大量发育良好的粗面内质网、高尔基复合体及具包膜的囊泡表明这些腺上皮分泌细胞是同其蛋白质合成密切相关的,同时大量存在的线粒体和微绒毛表明由腺上皮分泌细胞中粗面内质网合成的蛋白质在此处分泌入腺腔并分泌很活跃。根据透射电镜对一系列切片的观     

Osteoclastic features of multinucleated giant cells responding to synthetic hydroxyapatite implanted in rat jaw bone.

Multinucleated giant cells (MGCs) that responded to synthetic hydroxyapatite (HAP) implanted in rat mandibles were studied with electron microscopy. HAP used in this study sintered at 200 degrees C (HAP200) and at 125 degrees C (HAP1250) after the synthesis by a wet method. One to three weeks after the intraosseous implantation of HAP, MGCs responding to HAP200 had not only well-developed ruffled border and the clear zone but well-developed perinuclear Golgi complex, many mitochondria and vesicles in their cytoplasms. MGCs responding to HAP1250 had the clear zone, but not the ruffled border although they showed similar cytoplasmic features to those of MGCs responding to HAP200. They merely extended short slender cytoplasmic processes to HAP1250. These results suggest that although osteoclast-like MGCs respond to HAP implanted in the bone, the development of the ruffled border-clear zone system depends on physicochemical properties of HAP.     

Cytochemical energy-filtering transmission electron microscopy of mitochondrial free radical formation in paraquat cytotoxicity.

The generation of oxygen free radicals was investigated using cytochemistry and its energy-filtering transmission electron microscopy in reference to the toxic mediator for the herbicide paraquat. When isolated intact mitochondria from rat livers were incubated in a medium containing paraquat and NADH, a mitochondrial NADH-quinone oxidoreductase activity generated superoxide anions to cause the destruction of mitochondria which resulted in cell death. The superoxide anions were immediately converted into hydrogen peroxide, which then formed cerium perhydroxide deposits in the presence of cerium ions and precipitated on the outer surface of the mitochondrial outer membrane. This localization was also specifically identified by energy spectral imaging and image-electron energy loss spectral analyses. Precipitation reaction was scavenged by the addition of either cytochrome c or catalase and inhibited by dicoumarol (an inhibitor of NAD(P)H-quinone oxidoreductases). These cytochemical energy-filtering transmission electron microscopic results indicated that paraquat generated free radicals from the outer membrane of mitochondria.     

Electron microscopy of pathogenic yeasts Cryptococcus neoformans and Exophiala dermatitidis by high-pressure freezing

A high-pressure freezing method was used to observe the ultrastructure of pathogenic yeasts, Cryptococcus neoformans and Exophiala dermatitidis, after freeze-substitution and ultrathin sectioning. The method well preserved the cell structure in its natural state, since the capsule, cell wall, plasma membrane, nucleus, outer and inner nuclear membranes, nuclear pores, nucleolus, mitochondria, mitochondrial membrane and cristae, vacuoles, endoplasmic reticulum, Golgi apparatus, spindle pole body, ribosomes, lipid droplets, microtubules, actin filaments, and glycogen granules were clearly visible. The method was shown to freeze cells as deep as 0.1 mm by sectioning the sample perpendicular to specimen surface. The quality of the cell image was similar to that obtained by a rapid freezing method when compared using the same materials. Thus, high-pressure freezing would be useful for making serial ultrathin sections for three-dimensional analysis of cells, which should give basic information of structure and function of pathogenic yeast cells necessary for finding an effective therapy for mycoses.