Studies on cell surface conformation following injury. II. Scanning and transmission electron microscopy of cell surface changes following anoxic injury in Ehrlich ascites tumor cells.

Exposure of Ehrlich ascites tumor cells to anoxia resulted in rapid and characteristic conformational changes of cell surface topography. Combined scanning and transmission E/M studies revealed rapid alterations including simplification of the cell surface configuration with disappearance of microvilli which were replaced with formation of blebs and recesses at the cell periphery. These surface changes were accompanied by characteristic organelle alterations inside the cells which in this and other cellular systems have been shown to be reversible. Later, the cell surface topography became smoother and monotonic with small blebs and cribriform invaginations in addition to larger eruptions of the cell periphery. Combined transmission E/M studies revealed fragmentation of cellular membrane systems and lysis of organelles indicating the irreversible phase of anoxic injury. The rapid conformational surface changes encountered in Ehrlich ascites tumor cells following anoxia suggest the important role of the plasma membrane and its unfolding as a virtually instantaneous response of the cells to this injury.     

Characteristics of motor apparatus in testicular, epididymal and ejaculated spermatozoa. A study using demembranated sperm models

Morphological alterations of cytoplasmic organelles occur in the early stage of the cell fusion reaction induced by HVJ (Sendai virus) and these alterations are reversed in the late stage of the reaction. When the cells were treated with the virus at 37 °C for 3 min, the mitochondria became condensed, the cisternae of the endoplasmic reticula and Golgi stacks became highly distended, the inner space of the nuclear envelopes became enlarged, and the arrangement of 100 Å filaments became disordered. All these morphological changes were gradually reversed during further incubation at 37 °C and had been completely reversed by the end of the cell fusion reaction. These changes occurred at the time of interaction of the cell membrane with HVJ, and seemed to represent functional responses of the living cell to perturbation of the membrane resulting from its interaction with the virus.     

银杏贮粉室发生部位的珠心细胞程序性死亡的形态学观察

银杏（Ginkgo bilobaL)贮粉室的发生涉及位于珠孔端的珠心细胞的程序性死亡（PCD）,本研究观察了贮粉室发生过程中发生PCD的珠心细胞的形态学变化。这些珠心细胞在PCD过程中形态变化显著,细胞组分有序地降解,液泡在此起关键作用。在液泡化过程中,细胞质基质和一些细胞器被液泡所吞噬,此时的细胞器结构完整。当液泡膜破裂,细胞质基质消失之后。细胞器才逐步解体。最终,这些珠心细胞仅具有残留的细胞壁,随着胚珠的生长,细胞壁也被破坏,在整个PCD过程中,内膜系统发生明显改变;细胞质膜出泡,产生多泡体;形成多环膜结构;出现由膜包围的小体,其中含有细胞质基质和一些细胞器;液泡膜破裂;细胞器解体;细胞中出现大量的小膜泡。珠孔端的珠心表皮开裂形成贮粉室的开口有两种方式：一种为专一细胞的自溶,而另一种是在两个邻接细胞的中胶层处分离,没有发生细胞的自溶破裂。贮粉室开口位置的特定表皮细胞在开裂发生前就死亡,从而提前标示出表皮开裂的发生位置。这些细胞形态的变化反映出银杏珠心细胞的死亡是受发育调控的PCD过程。     

银杏贮粉室发生部位的珠心细胞程序性死亡的形态学观察

银杏(Ginkgo biloba L.)贮粉室的发生涉及位于珠孔端的珠心细胞的程序性死亡(PCD).本研究观察了贮粉室发生过程中发生PCD的珠心细胞的形态学变化.这些珠心细胞在PCD过程中形态变化显著,细胞组分有序地降解,液泡在此起关键作用.在液泡化过程中,细胞质基质和一些细胞器被液泡所吞噬,此时的细胞器结构完整.当液泡膜破裂、细胞质基质消失之后,细胞器才逐步解体.最终,这些珠心细胞仅具有残留的细胞壁.随着胚珠的生长,细胞壁也被破坏.在整个PCD过程中,内膜系统发生明显改变:细胞质膜出泡,产生多泡体;形成多环膜结构;出现由膜包围的小体,其中含有细胞质基质和一些细胞器;液泡膜破裂;细胞器解体;细胞中出现大量的小膜泡.珠孔端的珠心表皮开裂形成贮粉室的开口有两种方式:一种为专一细胞的自溶,而另一种是在两个邻接细胞的中胶层处分离,没有发生细胞的自溶破裂.贮粉室开口位置的特定表皮细胞在开裂发生前就死亡,从而提前标示出表皮开裂的发生位置.这些细胞形态的变化反映出银杏珠心细胞的死亡是受发育调控的PCD过程.     

Gonadotropins and cyclic adenosine 3',5'-monophosphate (cAMP) alter the morphology of cultured human granulosa cells

Morphological changes in human granulosa cells in culture were observed by phase, fluorescent, scanning electron and transmission electron microscopy following the addition of human chorionic gonadotropin (hCG), luteinizing hormone (LH), 8-bromocyclic adenosine 3',5'-monophosphate (cAMP) and cytochalasins B and D. In response to these agents, polygon-shaped granulosa cells with granular cytoplasm became rounded, leaving fingerlike processes attached to the substratum and adjacent cells. The changes in cell shape were accompanied by a centripetal movement of mitochondria and lysosomes to a perinuclear location. The morphological alterations appeared to be mediated by cyclic AMP and to be the result of a dismantling and reorganization of microfilament-containing stress fibers. Follicle-stimulating hormone (FSH), prolactin (PRL), growth hormone (GH), and human placental lactogen (hPL) did not provoke cell shape changes. We conclude that tropic hormones capable of stimulating progestin secretion by luteinized granulosa cells cause a change in cell structure in vitro which leads to a redistribution of organelles involved in steroid synthesis. The possible relationship of the cytoskeleton to steroidogenesis is considered.     

Ultrastructure of follicular atresia in the rat

Observations were made on the sequence of morphologic changes in atresia of medium-sized preantral follicles in the rat. Ultrastructural studies indicated that in both control and hormonally treated animals granulosa cell changes, including nuclear condensation and alterations in cytoplasmic organelles, occurred prior to effects on the oocyte. In more advanced stages of atresia, extensive disruption of granulosa cell cytoplasm was associated with loss of microvilli and cytoplasmic vacuolization in oocytes. The findings are consistent with the view that follicular atresia begins with alterations in granulosa cells, effects on the oocyte occurring later in the atretic process.     

Mitochondrial remodeling in cancer metabolism and survival: Potential for new therapies

Mitochondria are semi-autonomous organelles that play essential roles in cellular metabolism and programmed cell death pathways. Genomic, functional and structural mitochondrial alterations have been associated with cancer. Some of those alterations may provide a selective advantage to cells, allowing them to survive and grow under stresses created by oncogenesis. Due to the specific alterations that occur in cancer cell mitochondria, these organelles may provide promising targets for cancer therapy. The development of drugs that specifically target metabolic and mitochondrial alterations in tumor cells has become a matter of interest in recent years, with several molecules undergoing clinical trials. This review focuses on the most relevant mitochondrial alterations found in tumor cells, their contribution to cancer progression and survival, and potential usefulness for stratification and therapy.     

马鹿卵母细胞体外培养与体外受精的超微结构

用FSH 对马鹿进行超数排卵,通过抽吸法和切割法采集卵泡卵母细胞,用M199 为基础的培养液在38.5℃、5%CO₂ 和饱和湿度条件下对马鹿卵母细胞进行体外培养与体外受精培养,利用透射电镜观察不同时期马鹿卵母细胞的超微结构,旨在揭示马鹿卵母细胞体外培养前、培养后及受精后超微结构的变化规律。结果表明,培养前卵丘细胞紧紧包围卵母细胞,卵母细胞表面的微绒毛细长,伸入透明带内,皮质区及细胞中心分布大量的细胞器。培养后卵丘细胞与卵母细胞结合松散,卵母细胞表面微绒毛短粗,倒伏于卵表面,第一极体无核,皮质颗粒在皮质区成层排列,细胞质中细胞器分布均匀。受精后卵母细胞表面的微绒毛由倒伏而竖起,第二极体有核,细胞质中细胞器丰富,主要分布于细胞中心。     

Effect of chemical carcinogens on the ultrastructure of cultured differentiating myogenic cells

The electron microscope studies have been carried out on primary monolayer tissue culture obtained from body tissues of rat and C3H mouse embryos. The cells of tissue culture were mainly myoblasts and fibroblast-like cells. The cultures were treated with two different carcinogenic substances--benz(a)-pyrene (BP) and methylnitrosonitroguanidine (MNNG). The changes were uniform and showed some alterations in formation of cell complexes, the inhibition of development and maturing of muscle elements, and distrophy of cytoplasmic organelles. The revealed distinction in morphological reaction of myogenic cells to the effect of BP and MNNG were wave-like myofibrillar structures in MNNG-treated cultures.     

Lysosomal uptake of isolated cell organelles microinjected into HeLa cells

Lysosomes and microsomes were isolated from rat liver and microinjected into the cytoplasm of HeLa cells. The fate of the transplanted organelles and their effects on the recipient cells were followed in the electron microscope at various time intervals after administration. Needle injection with buffer or sucrose did not seem to evoke any ultrastructural alterations, such as induced autophagy or other signs of sublethal cell injury. Recipients of microinjected cell organelles elicited a rapid and conspicuous increase in membrane-bounded cytoplasmic vacuoles, concomitant with the disappearance of the injected material. Golgi complexes became abundant with many small vesicles clustering around their cisternae. The volume density of the lysosomal compartment increased 2-3-fold after organelle injection as compared with control-injected (0.3 M sucrose) or noninjected cells. Our preliminary results show that isolated cell organelles can be microinjected into cells n culture and indicate that the microinjected organelles were segregated from the cytoplasm into membrane-bounded vacuoles probably through autophagolysosome formation. Thus, this technique offers an additional approach for studies on the segregation and degradation of cell organelles in somatic cells and may enable more detailed analyses on the mechanisms of autophagic sequestration of specific cell organelles.     

The influence of cryopreservation on the ultrastructural morphology of human thyroid cells

The purpose of this study was to investigate the effects of the freeze-thaw procedure on the ultrastructural features of human thyroid cells. Four different stages of thyroid cell preparation were compared: (1) fresh surgical tissue, serving as control, (2) cell suspension before freezing, (3) cell suspension after thawing, and (4) monolayer cell culture, obtained from cells after thawing. Electron microscopic examination of cells from each stage showed that the freeze-thaw procedure used caused only minor intracellular alterations restricted to mitochondria. Some of these organelles showed low-amplitude swelling or occasionally appeared condensed. These ultrastructural changes were not paralleled by a decrease in the vitality or sensitivity of the cryopreserved cells to stimulating agents.     

Changes in cell structure during the formation of root aerenchyma inSAGITTARIA LANCIFOLIA (Alismataceae)

In many wetland species, root aerenchyma is produced by the predictable collapse of root cortex cells, indicating a programmed cell death (PCD). The objective of this study was to characterize the cellular changes that accompany this PCD in the marsh species Sagittaria lancifolia. Structural changes in membranes and organelles were examined during development of root cortex cells to compare with previous examples of PCD. The organization of cortical microtubule (CMT) arrays in root cells from S. lancifolia was also evaluated as a possible predictor of cell lysis. Nuclear fragmentation and condensation were the earliest changes observed in cells undergoing lysis. Breakdown of the tonoplast and other organelles and disruption of the plasma membrane followed. After loss of cytoplasm, cells collapsed to form gas spaces. These results were compared to collapse of root cortical cells of Zea mays and Oryza sativa during aerenchyma development. Changes in the appearance of the cytoplasm of all three species were similar at later stages of aerenchyma development. The relative timing of disintegration of the tonoplast and middle lamella appeared to differ among the three species. Changes in the organization of CMT arrays did not appear to be a predictor of PCD in S. lancifolia. Aerenchyma production in plants involves a type of PCD that is morphologically distinct from PCD described from many animals.     

Biomphalaria glabrata (Gastropoda): effect of urethane on the morphology and function of hemocytes, and on susceptibility to Schistosoma mansoni (Trematoda)

Urethane (ethyl carbamate) anesthesia of Biomphalaria glabrata resulted in several rapid changes to the snail's blood picture. At 2 hr postexposure (PE) to the drug, there was an elevation in the prevalence of acid phosphatase (APase)-positive hemocytes, a significant increase in the number of APase granules per cell, a three fold increase in circulating blood cell number, and a decrease in the percentage of hemocytes expressing a cell subpopulation-specific surface membrane epitope (BGH₁). However, urethane had little effect on erythrophagocytosis by host hemocytes. All of the observed changes returned to control levels by 12 hr PE to the drug. Blood cells cultured with various concentrations of the anesthetic in vitro did not exhibit any alterations in the parameters described above. Since circulating hemocytes represent the primary effector component involved in internal defense reactions, the effect of urethane-induced changes in the composition of circulating blood cells on susceptibility to a larval trematode, Schistosoma mansoni, was examined. Such changes had no apparent effect on host susceptibility since the rate of infection for urethane-exposed snails (88.2%) was the same as for nonurethane-treated B. glabrata (82.4%). However, the effects of urethane-induced changes in hemocyte number and composition on other invading organisms is not known. Therefore, it is suggested that such alterations should be considered when internal defense reactions are studied in snails exposed to this drug and other commonly used anesthetics.     

Destructive and restorative processes of the liver in rats under intensive physical loading

The ultrastructure of rat liver cells after running exercise was investigated. When rats were trained for a month and sacrificed immediately after the last exercise it was revealed that the number of liver cells mitochondria increased, but many of them had alterations: mitochondria became swollen, had lucid matrix. There were some variations in degree of alterations between different mitochondria: a) in the same hepatocyte, b) in different hepatocytes of the same animal, that was connected with individual sensitivity of organelles on the levels of the cell and of the organ. Rough endoplasmic reticulum bore few ribosomes. Glycogen was absent. There were abundant vesicles of smooth endoplasmic reticulum, autophagic vacuoles and peroxisomes in the liver cell cytoplasm. Adaptation of rat liver to the exercise programme becomes evident by 1.5 month of exercise. Mitochondria and rough endoplasmic reticulum were numerous and of normal structure. There were many peroxisomes and glycogen granules in the cytoplasm of hepatocyte. The presence of large autophagic vacuoles in the cytoplasm of some hepatocytes were obviously connected with more rapid destruction of some organelles, than in control.     

Effect of hydrostatic pressure on the morphology and ultrastructure of wild-type and trehalose synthase mutant cells of Saccharomyces cerevisiae

AIMS: Saccharomyces cerevisiae was used for studying the physiological effects of hydrostatic pressure. METHODS AND RESULTS: The effects of hydrostatic pressure on the ultrastructure of wild-type and trehalose-6-phosphate synthase (tps1) mutant cells were investigated by transmission electron microscopy. Pressure induced several morphological changes in wild-type and tps1 cells, the latter showing greater structural alterations. When the cells were submitted to a preheat treatment they both acquired resistance to the pressure treatment. CONCLUSION: As the tps1 mutant was 1000-fold more barosensitive than its parental strain, it showed greater structural alterations compared with the wild-type. Microscopic images of the yeast cells suggested that hydrostatic pressure induced changes in the cytoskeleton and therefore, on the cell wall and in the dynamics of the organelles. SIGNIFICANCE AND IMPACT OF THE STUDY: This work presents the effects of hydrostatic pressure on the morphology of yeast cells and confirms the importance of several different factors in the protection of cells against stress.     

Movement of Cell Organelles and the Geotropic Curvature in Roots of Norway Spruce (Picea abies)

The geotropic development in roots of Norway spruce [(Picea abies (L.)] H. Karst, has been followed by light and electron microscopy and compared with the movement of cell organelles (statoliths) in the root cap cells. The geotropic curvature develops in two phases: (a) an initial curvature in the root cap region, which results in an asymmetry in the extreme root tip and which appears after about 3 h stimulation in the horizontal position; and (b) the geotropic curvature in the basal parts of the root tip, which after 8 h is distributed over the entire elongation zone. A graphic extrapolation, based on measurements of the root curvatures after various stimulation periods, indicates a presentation time in the range of 8 to 10 min. The root anatomy and ultrastructure have been examined in detail in order to obtain information as to which organelles may act as gravity receptors. The root cap consists of a central core (columella) distinct from the peripheral part. The core contains three to four rows of parenchymatic cells each consisting of 15 to 18 storeys of statocyte cells with possibly mobile cell organelles. Amyloplasts and nuclei have been found to be mobile in the root cap cells, and the movement of both types of organelles has been followed after inversion of the seedlings and stimulation in the horizontal position for various periods of time at 4°C and 21°C. Three-dimensional reconstructions of spruce root cap cells based on serial sectioning and electron microscopy have been performed. These demonstrate that the endoplasmic reticulum (ER)-system and the vacuoles occupy a considerable part of the statocyte cell. For this reason the space available for free movement of single statolith particles is highly restricted.     

Effects of aluminum in red spruce (Picea rubens) cell cultures: Cell growth and viability, mitochondrial activity, ultrastructure and potential sites of intracellular aluminum accumulation

The effects of Al on red spruce ( Picea rubens Sarg.) cell suspension cultures were examined using biochemical, stereological and microscopic methods. Exposure to Al for 24–48 h resulted in a loss of cell viability, inhibition of growth and a significant decrease in mitochondrial activity. Soluble protein content increased in cells treated with Al. Using energy-dispersive X-ray microanalysis on sections of freeze-substituted cells that had no obvious disruption in cytoplasmic or cell wall structure, Al (always in the presence of P) was detected in dense regions in cell walls, cytoplasm, plastids and vacuoles after 48 h exposure to Al. Stereological quantification of spruce cell structure showed that, after 24 h of Al treatment, intact cells had increased vacuolar and total cell volume, but the nuclear volume did not change. In addition, Al treatment resulted in increased surface area of Golgi membranes and endoplasmic reticulum. The biochemical and ultrastructural alterations in red spruce cells, in combination with the presence of Al in cellular organelles of visually intact cells, suggest that Al movement occurred across the plasma membrane without major cellular disruption. Detailed short-term time course studies are needed to determine if intracellular Al in these cells results from its passage into cells through submicroscopic lesions in the plasma membrane or it is taken up into the symplast through the intact membrane by an active, but slow, process.     

Ultrastructure of epithelial cells in rat's epididymal caput in experimental hyperprolactinemia induced by metoclopramide

The aim of the performed studies has been to find out wether or not the ultrastructural alterations of the epithelial cells in the rat's epididymal caput occur in hyperprolactinemia induced by metoclopramide and to see if the observed changes are of reversible character. It has been revealed that prolactin concentration was twice as high as in control animals due to peritoneal administration of metoclopramide in a dose of 2.2 mg/kg body mass, given for 14 days. The ultrastructural alterations in the principal cells of epididymal caput affected cellular organelles being involved in proteins synthesis, glycosylation, secretion as well as energetic processes. They were manifested by decreased amount of rough endoplasmic reticulum, widening of its cisternae combined with degranulation, distension of Golgi apparatus cisternae, elevated number of vesicles in apical part of the cells, and changes in mitochondria. The termination of metoclopramide administration made prolactin concentration exhibit values being almost similar to those determined in control rats, whereas the ultrastructural changes in the principal cells were found to be reversible.     

Lysosomes and lysosomal proteins in cancer cell death (new players of an old struggle)

Death of cancer cells influences tumor development and progression, as well as the response to anticancer therapies. This can occur through different cell death programmes which have recently been shown to implicate components of the acidic organelles, lysosomes. The role of lysosomes and lysosomal enzymes, including cathepsins and some lipid hydrolases, in programmed cell death associated with apoptotic or autophagic phenotypes is presented, as evidenced from observations on cultured cells and living animals. The possible molecular mechanisms that underlie the action of lysosomes during cell death are also described. Finally, the contribution of lysosomal proteins and lysosomes to tumor initiation and progression is discussed. Elucidation of this role and the underlying mechanisms will shed a new light on these 'old' organelles and hopefully pave the way for the development of novel anticancer strategies.     

The ocellus of the cockroach,Periplaneta americana (Blattariae)

Summary The ocelli of Periplaneta americana were studied by light and electron microscopy. The view that the ocellus of the cockroach represents a degenerated structure can no longer be supported. All organelles necessary for function are present.The club-shaped retinular cells lie homogeneously distributed in the cupule of the ocellus. Rhabdoms are seen as sickle-, y-, x-or star-shaped structures with up to six cells in formation. Cells were found which had formed two rhabdomeres.The mass of cell organelles lies in the cytoplasm between the cell nucleus and the rhabdom. Smooth endoplasmic reticulum is wound into a spindle formation of considerable size at the origin of the axon in some cells. A cylindrical body in which 10–40 microtubules are packed, as yet unknown in insect retinular cells, is described.The receptory area of the ocellus terminates in a tapetum which contains granules, soluble in alcohol. The axon bundles of the retinular cells run through the tapetum and immediately thereafter make synaptic contact with dendrites of the ocellar nerve cells, while still within the ocellus.The authors are indebted to Mrs. Margaret Weber-Wood for her linguistic assistance