The effects of bilateral adrenalectomy on the fine structure of the rat myocardium

The subcellular effects of bilateral adrenalectomy on the rat myocardium were examined on 50 male rats. The animals, divided into groups of ten, were killed 3, 17, 18, 19 and 21 after adrenalectomy. The early changes consisted of moderate intracellular edema of many cardiac muscle cells and disarrangement of their myofibrils. The late changes consisted of prominent intracellular edema of many cardiac muscle cells, destruction of numerous myofibrils, dilatation of the sarcoplasmic reticulum and accumulation of numerous irregular mitochondria in subsarcolemma areas of the sarcoplasm. The lipofuscin granules seemed to be increased in number. Many endothelial cells were edematous and platelet aggregations filled the lumen of some small vessels.     

Myocardial ultrastructure and electrocardiograms of the hummingbird under normal and experimental conditions

Ventricular myocardium from several adult specimens of hummingbirds (Eupetomena macroura macroura) were subjected to study by electrocardiography and by light and electron microscopy under normal and experimental conditions as provided by injection of 2,4-dinitrophenol (DNP) and ether anesthesia. The birds were captured in Brazil, and were studied because of their high heart rates 428/460 minute on the average, seeking correlations of structure and function under normal conditions as well as after pharmacological stimuli. Under normal conditions, the hummingbird showed a highly developed sarcoplasmic reticulum, many gigantic mitochondrial with numerous tightly packed parallel mitochondrial cristae and tubules, and few small, dark bodies. The amount of sarcosomes is approximately equivalent to that of myofibrils. As seen in longitudinal sections of muscle fibers, often the junctions between successive mitochondria and both indentations of mitochondria and of the nuclear envelope occurred at the level of the Z bands. This gave the impression that contraction of the myofibrils shortened the nucleus and caused it to wrinkle. Most mitochondrial bulged at their middle as if they had been compressed between successive Z bands, suggesting a more resistant area at the level of these bands than in the rest of the myofibril. Almost no glycogen granules were found, probably because the high metabolic rate of the heart did not allow free storage of such carbohydrates. The administration of DNP was responsible for changes in the ECG (tachycardia and other alterations) and in the structure of the myocardium: large dilations in the sarcoplasmic reticulum and the appearance of small spaces in the mitochondria.     

单甲氧基聚乙二醇—超氧化物歧化酶减轻低氧对兔心肌超微结构损伤

用雄性日本大耳兔（２．５￣３ｋｇ）每组５￣１２只，除常氧对照组外，其余各组分别模拟海拔高度５０００ｍ低压性低氧２４ｈ，左右心室肌超微结构损伤明显，主要表现为线粒体膜破损，嵴部分消的。肌丝间隙增大，肌原纤维断裂。溶酶体增多，糖原颗粒减少，氏氧前由股静脉注入单甲氧基聚乙二醇－超氧化物歧化酶的兔，肌原纤维排列整齐。线粒体含量丰富嵴密集，与肌原纤维基本呈平行。另测定低氧不同时间左右心室肌超氧化物歧化酶活性     

Electron microscopic observations on the development of S-A and A-V nodal tissues in the human embryonic heart

Summary Electron microscopy of the S-A and A-V nodes in the 15 human embryonic hearts revealed specific morphological characteristics of the tissue. In the embryonic S-A node muscle, a diffuse distribution of abundant mitochondria and ribosomes as well as of slim myofibrils was noted, while in the adjacent atrial myocardium glycogen occupied a vast area of the cytoplasm so as to leave myofibrils and scanty mitochondria in the peripheral part of the cell. Intrasarcoplasmic smooth-surfaced membrane system appeared in the S-A node muscle first at the 4 months stage. Embryonic A-V node muscle was characterized by its enormously rich content of fat droplets, which were in close association with glycogen. Extremely scanty nerve supply in the embryonic A-V node region examined was in a peculiar contrast to an earlier, abundant invasion of nerves into the S-A node.This research was suggested and consulted by Dr. I. Asami, Department of Anatomy, University of Tokyo.     

Effect of a Transient Period of Ischemia on Myocardial Cells: II. Fine Structure During the First Few Minutes of Reflow

Changes produced in the posterior papillary muscle of the dog following 40 minutes of circumflex artery occlusion and 0 to 20 minutes of blood reflow were studied by electron miroscopy. With no reflow of blood, myocardial cells were modestly swollen, contained amorphous matrix densities in the mitochondria, had aggregation and margination of nuclear chromatin and relaxation of myofibrils. With as little as 2 minutes of blood reflow, cells developed contraction bands and were greatly swollen due to a generalized increase in sarcoplasmic space, formation of vacuoles and swelling of mitochondria. Frequently, cell membranes were lifted away from the myofibers, forming large subsarcolemmal blebs which appeared capable of compressing adjacent capillaries. The extracellular space did not appear to be enlarged, and the marked tissue edema found after reflow was due primarily to accumulation of intracellular fluid. In addition to explosive cell swelling, there was, over the 2- to 20-minute period of reflow, a progressive increase in size and number of granular mitochondrial dense bodies of the calcium accumulation type. No significant changes in lysosomes were observed. The speed with which the morphologic changes developed during very early reflow periods suggests that irreversible ischemic injury produces a defect in cell volume regulation during the phase of ischemia and that this defect becomes manifest if arterial flow is restored to the affected cells.     

Ultrastructural damages in rat myocardium induced by hydrogen peroxide injection

Rat myocardium was examined by electron microscopy after hydrogen peroxide injection through the tail vein. At the initial stage (1–6 hr after injection of hydrogen peroxide), ultrastructural damages included slight edema of the myocytes, dilation of the sarcoplasmic reticulum, disruption of the myofibrils, interstitial edema and the disappearance of elastin. At the early stage (1–7 days), in addition to the ultrastructural damages of the myocardium in the initial stages, swelling and fusion of mitochondria, irregularly-arranged collagen networks and type III bleb formations were observed. At the later stage (14–28 days), tissue damages had recovered. There was little ultrastructural damage in the normal control myocardium. The relationship between oxygen-derived free radicals and early ischemic or ischemia-reperfusion injury is discussed.     

LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS OF THE MYOCARDIUM OF DOGS IN HEMORRHAGIC SHOCK

Morphologic change of the myocardium of the dog were observed in oligemic and normovolemic shock produced by Wiggers' standard method.
Subendocardial hemorrhages, usually superficial and located mostly in the ventricular aspect of the septum, were remarkable in the normovolemic shock group, but rare in the oligemic shock group. The zonal lesion appeared in the early period of oligemic shock becoming more apparent with lapse of time. Ultrastructural studies revealed some differences of the findings of the zonal lesion between oligemic and normovolemic shock. In oligemic shock, the zonal lesion was identical to the supercontraction of myofilaments and dislocation of mitochondria. Supercontraction of myofibrils was usually unilateral, and herniation of damaged myocytes was frequently noticed in the unilateral lesion. In the normovolemic shock, supercontracted areas near the intercalated disc were usually stretched and the myofilaments became irregular in arrangement. In addition, the accumulation of glycogen granules and presence of clear flocculent areas were observed in the cytoplasm of some myocardial cells.
Cell edema, swelling and destruction of mitochondria and contraction bands were found in the damaged myocyte, especially in the terminal stage of normovolemic shock. Swelling of the capillary endothelial cell was already observed in the early period of oligemic shock. In addition, the pathogenesis of the zonal lesion and the mechanism of cardiac depression in hemorrhagic shock were discussed.     

THE FORMATION OF ENLARGED AND GIANT MITOCHONDRIAIN THE AGING PROCESS OF HUMAN HEPATIC CELLS

Measurement of area, circumference and total length of membrane profile of mitochondria of hepatic cells in 61 human biopsy materials (age range 21 to 81 years) have been ultramicrometrically performed on electron micrographs, supplemented by electroncytochemical examination of cytochrome c oxidase activity in some cases. The mitochondria decreased in number after 60 years of age. The first stage of compensation for the numerical loss of mitochondria was achieved by an increase of cristae in each mitochondrion, followed with a five year lag by an increase in their size. Formation of enlarged and giant mitochondria in aging process following the significant decrease in their number, may be considered to be of similar mechanism to polyploidization of the nucleus, whose division is interfered.     

Ultrastructure of the atrioventricular junctional area in the heart of Molossus molossus Pallas 1766 (Chiroptera: Molossidae)

The atrioventricular junctional area (AVJA) consists of a group of structures that connects the atrial and ventricular myocardium. Five hearts of an insect-eating bat were studied in light and transmission electron microscopy. In M. molossus, the AVJA consists in a mass of muscle fibers intermingled with variable amount of connective tissue and blood vessels surrounded by the adjacent myocardium and the attachment of the right atrioventricular and aortic valves in the fibrous skeleton. In light microscopy, conducting cells of the AV node and bundle can be distinguished from working cells: smaller size, paler staining reaction and the presence of e sheath of connective tissue surrounding each cell (largely composition by type I collagen fibers). Three cell types are observed in the AVJA. Nodal cells are irregular with few cytoplasmic organelles and several slender sarcolemmal modifications. Myofibrils are sparse and not clearly observable. Transitional cells are spindle-shaped and grouped together into bundles. The cytoplasm, poor in glycogen, has scarce electron-density and myofibrils organized into sarcomeres. Caveolae is observed randomly distributed at the periphery of the cell. The AV bundle cells are elongated with clusters of myofibrils organized in the periphery and a glycogen free area around the nucleus. Ventricular cells are bigger than the atrial ones and show well-developed myofibrils in alternated rows with mitochondria. Lipid droplets are seen near mitochondria and glycogen granules. Intercalated discs and T-tubules are found in working cells but not in conducting ones. The fibrous skeleton has collagen fibers intercalated with fibroblasts.     

衰老晚期海马CA1区锥体细胞线粒体改变──电镜定量分析

选用成年健康SD大鼠20只.分为青年组（3个月）和老年组（34～36个月）二个实验组，每组10只。应用透射电镜结合体视学方法观察并比较了海马CA1区锥体细胞线粒体的变化，结果如下：和青年组相比，老年组肿胀、变性线粒体增多，体视学分析显示老年组线粒体密度和平均体积增大，线粒体数密度和比表面减少，线粒体切面积大小频数分布图向右侧迁移，显示到衰老晚期较小的线粒体数减少.较大的线粒体数增多。本研究结果表明，衰老晚期海马CA1区锥体细胞线粒体严重退变，进入失代偿状态。     

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. Report of an autopsy

We present an autopsy report on a 14-year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), placing emphasis on the mitochondrial enzymatic histochemistry of the 3 types skeletal muscle and cardiomyocytes. Generalized muscular atrophy, cardiac hypertrophy, cerebral cortical laminar necrosis, basal ganglia calcification and liver steatosis were observed. In the skeletal muscles, modified Gomori's trichrome staining demonstrated scattered ragged red fibers, and histochemical staining for mitochondrial enzymes showed intense positivity in the subsarcolemmal zones of some muscle fibers. Some of the hypertrophic cardiomyocytes also showed a ragged red appearance with the modified Gomori's trichrome stain. Histochemical staining for mitochondrial enzymes showed patchy loss of enzymatic activity in the myocardium. Electron microscopically, extreme accumulation of enlarged mitochondria and severe loss of myofibrils was observed in both skeletal muscle fibers and cardiomyocytes. The arteriolar smooth muscle cells also showed a mild increase in mitochondria.     

Effects of calcium depletion and calcium paradox on the ultrastructure of the frog heart

The alterations in the ultrastructure of the isolated perfused Rana ridibunda hearts that were subjected to prolonged calcium depletion and reperfusion with calcium containing medium are described using thin section electron microscopy. Deprivation of calcium resulted in broadened intercellular spaces and in mild cell swelling. Cell to cell contact was maintained throughout calcium depletion, while myofibrils and mitochondria remained intact. Reintroduction of calcium containing buffers to calcium depleted hearts resulted in an irreversible injury of the frog myocardial cells. The main characteristics of the reperfusion induced damage were contraction band formation, distortion and degradation of the myofibrils, extensive swelling of the mitochondria and formation of intramitochondrial electron dense deposits. Mitochondrial aggregation, intermitochondrial junctions, expulsion of the mitochondria to the sarcolemmal membrane and peripheral condensation of nuclear chromatin were also observed. Our results indicate that frog myocardial cells show a marked resistance even to a prolonged calcium depletion, retaining their integrity and their contact. However, the following reperfusion greatly alters the ultrastructure of frog myocardium and the observed alterations are typical of the irreversible damage induced in calcium overload situations.     

PATHOLOGY OF EXPERIMENTAL RADIATION PANCARDITIS I.

Radiation-induced heart injuries were morphologically studied by using the rabbits irradiated with a single dose of 3,000R (group I) or 300R of X-ray group II) from 1 hour until 6 months. There was no essential difference in the lesions of the hearts from group I and that of group II. Acute epicarditis was found as early as 1 hour after irradiation and it became maximum in severity at 1-2 days. In the myocardium, there were degeneration and resolution of the myocardial cell, various architectural changes of mitochondria, and disorganization of the intercalated disc. Polymorphonuclear cell infiltration and endothelial injuries of the capillaries occurred in the interstitial tissue. In addition, endocarditis with or without thrombus formation was often found. Acute inflammation was seen in the myocardium of group II rather later than that of group I, but it disappeared earlier. In the later stage, fibrosis finally occurred in the epicardium and endocardium. Glycoprotein degeneration of the muscle cells and fibrosis appeared in the myocardium. The pathogenesis of radiation pancarditis is thought to be dependent not only on the disturbance of microcirculation caused by endothelial cell damage of the capillaries, but also on alterations of the myocardial mitochondria as a result of direct injury.     

Chronic effects of ethanol on cultured myocardial cells: ultrastructural and morphometric studies

Ultrastructural alterations of the myocardium due to chronic ethanol exposure were investigated using an in vitro system-mouse ventricular myocardial cells in a monolayer culture, which were spontaneously and synchronously contracting-by chronic exposure to 12.5, 50, and 200 mM ethanol for up to 21 days. Morphometric analyses revealed that exposure to 12.5 mM ethanol for 14 days induced an increase in the number of residual bodies, which are lysosomes containing electron-dense, amorphous materials. Some cells exposed to 50 mM ethanol for 14 days contained an accumulation of glycogen granules, increasing in inverse proportion to the mitochondrial volume. The volumetric proportion of myofibrils on day 14 decreased as the ethanol dose became lower, and was in proportion to large and giant mitochondria within the limits of three ethanol groups. Dose-dependent increases in the size and volumetric proportion of mitochondria were observed after the 14-day exposure; at a low dose (12.5 mM) mitochondria of usual size tended to increase, whereas at a high dose (200 mM) giant mitochondria increased. Coincidentally with this mitochondrial increase or gigantism, all ethanol groups showed higher beat rates than the control. Consequently, it is most likely that chronic 14-day exposures to these three ethanol doses remodel the cellular function of the in vitro myocardium in different ways; the 200-mM dose induced mitochondrial hypertrophy, an adaptive response to switch myocardial energy metabolism over to some special one; the 50-mM dose was a boundary dose; and the 12.5-mM dose mostly mimicked the chronic in vivo administration of ethanol and induced slightly degenerative alterations-increased residual bodies and lysosomes, decreased myofibrils and lowered mitochondrial respiratory function.     

Giant mitochondria distinct from enlarged mitochondria in secretory and ciliated cells of gerbil trachea and bronchioles

Numerous mitochondria ranging from slightly larger than normal to several micrometers in diameter (giant) were found in about one-half the serous secretory cells in the surface epithelium of the normal gerbil trachea and proximal bronchi. Tracheal serous cells of mice also were found to contain numerous giant mitochondria. Clara cells of gerbil bronchioles contained abundant giant mitochondria in addition to normal tubular mitochondria and the second population of enlarged spherical mitochondria that have been described in Clara cells of several genera. In contrast, mouse Clara cells revealed the normal tubular and the enlarged spherical mitochondria but no giant mitochondria. A survey of a number of cell types in gerbils failed to disclose hypertrophied mitochondria outside tracheobronchial surface epithelium and bronchioles. The mitochondrial enlargement resulted from an increase of matrix but not cristae. The expansion of matrix displaced the relatively sparse cristae into small collections compressed against the outer membrane. The prevalence of giant mitochondria and of granular endoplasmic reticulum is similar among cells, and these two organelles are codistributed within cells. The megamitochondria and granular reticulum occupy a central stratum, whereas normal mitochondria occur in the apical and basal regions. The giant mitochondria are considered related to a normal biologic activity that is characteristic of respiratory tract epithelium of mice and gerbils selectively and is more prominent in secretory cells than in ciliated cells.     

An ultrastructural and histochemical study of rat atrial myocardium

A study was made of the ultrastructural and histochemical characteristics of atrial muscle cells. The myofibrils of these cells do not converge at the nuclear poles as in the ventricular cells, but leave large sarcoplasmic spaces in the central cores, which contain mitochondria, small amounts of rough-surfaced sarcoplasmic reticulum, free ribosomes and one or more well developed Golgi complexes. Numerous cytoplasmic granules, many of which are closely associated with the Golgi material, are present in these cells. These granules can be demonstrated in paraffin sections by the Bowie stain. The smooth-surfaced sarcoplasmic reticulum of atrial fibers consists of a meshwork of interconnected tubules which pass uninterruptedly from one sarcomere to another. No transverse dilatations or T tubules are present as in ventricular cells; however, there are numerous subsarcolemmal cisterns consisting of flattened dilatations of sarcoplasmic reticulum which lie in close proximity to the internal surface of the sarcolemma. There is considerable variation from one cell to another in the number and compactness of arrangement of the myofibrils, and in the abundance of other cellular components. On the basis of the above findings, we suggest that atrial muscle cells may have a secretory as well as a contractile function.     

Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like Episodes

We present an autopsy report on a 14-year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), placing emphasis on the mitochondrial enzymatic histochemistry of the 3 types skeletal muscle and cardiomyocytes. Generalized muscular atrophy, cardiac hypertrophy, cerebral cortical laminar necrosis, basal ganglia calcification and liver steatosis were observed. In the skeletal muscles, modified Gomori's trichrome staining demonstrated scattered ragged red fibers, and histochemical staining for mitochondrial enzymes showed intense positivity in the subsarcolemmai zones of some muscle fibers. Some of the hypertrophic cardiomyocytes also showed a ragged red appearance with the modified Gomori's trichrome stain. Histochemical staining for mitochondrial enzymes showed patchy loss of enzymatic activity in the myocardium. Electron microscopically, extreme accumulation of enlarged mitochondria and severe loss of myofibrils was observed in both skeletal muscle fibers and cardiomyocytes. The arteriolar smooth muscle cells also showed a mild increase in mitochondria. Acta Pathol Jpn 39: 599 606, 1989.     

小白鼠心肌肌原纤维和线粒体年龄性变化的体视学分析

本文采用体视学方法,定量研究了胚胎16日至生后13个月的小白鼠左心室肌细胞肌原纤维和线粒体含量的年龄性变化。从所获得的12个体视学参数的结果分析表明。(1)在发育过程中,心肌细胞产能结构的体积增长快于细胞体积和肌原纤维体积的增长;(2)胚胎末期,心肌线粒体体积显著增大,以满足此时期心脏功能活动增强的需要;(3)线粒体结构的发育至生后20日基本完成,功能的发育于生后60日更完善;(4)生后4日左右是小白鼠心肌线粒体结构改建的重要时期。     

卵丘细胞凋亡对体外培养卵母细胞发育潜能的影响

目的 研究体外培养中卵丘细胞凋亡对卵母细胞结构的影响,探讨体外受精中可用卵丘细胞凋亡率预测卵母细胞发育潜能的原因.方法 对GV期人卵丘-卵母细胞复合体进行体外成熟培养,用HE染色、DAPI染色和原位末端标记(TUNEL)法标记3种方法对单卵卵丘细胞凋亡率进行检测.分为凋亡率高和低的2组,用光镜和透射电镜观察卵母细胞的结构.对MⅡ期卵母细胞进行体外受精,培养2d后在光镜下评价胚胎质量.结果 卵丘细胞凋亡率低的卵母细胞结构和发育潜能良好;卵丘细胞凋亡率高的卵母细胞发育潜能差,存在各种结构异常,包括围卵周隙不均,对应不同部位的细胞质发育不同步;细胞质中出现堆积不均的细胞器团、次级溶酶体、及可能由溶酶体降解造成的大量空隙;线粒体外膜和嵴模糊、膨大,呈现凋亡迹象;第一极体碎裂;透明带异常增厚或变薄.相应的卵丘细胞微绒毛和细胞连接减少.结论 揭示了卵丘细胞凋亡对卵母细胞结构的影响,揭示了卵丘细胞凋亡率影响卵母细胞发育潜能的原因.     

Cardiomyopathy secondary to systemic triglyceride storage disease

Ultrastructural changes of a biopsied myocardium were observed by transmission electron microscopy in a patient with cardiomyopathy secondary to systemic triglyceride storage disease with Jordans' anomaly. There were many lipid droplets in the cardiocytes, and lipofuscin and mitochondria were increased. The volume fraction of myofibrils in the cardiocytes decreased because of an abundance of lipid droplets and mitochondriosis. Myocardial contractility may have been reduced by myofibrillar scarcity and low energy production resulting from an abnormality in the metabolism of fatty acids in the cardiocytes.This study was presented at the 26th Annual Meeting of The Clinical Electron Microscopy Society of Japan, Kochi, October 6, 1994. This paper was nominated by the chairperson of the annual meeting of the Society.