The presence of intracytoplasmic confronting cisternae of the endoplasmic reticulum in osteosarcoma cells in interphase

Confronting cisternae of the endoplasmic reticulum recognized in tumor cells of 7 cases of osteosarcoma were presented. They were found in the mitotic cells as well as in the cytoplasms of interphase cells. The more the mitotic cells were observed in 1 micron-thick sections, the more frequently those membranous structures were encountered in the corresponding ultrathin sections. In the interphase cells, such structures were located around Golgi apparatus or close to the nucleus. Occasionally, they were composed of a pair of closely apposed cisternae of the nuclear membrane and the rough endoplasmic reticulum. These results seem to indicate that the nuclear envelope which is disrupted and reformed during mitosis in rapidly proliferating cells takes part in the formation of the confronting cisternae of the endoplasmic reticulum.     

Tubuloreticular inclusions and paired cisternae induced in human lymphocytes cultured with Staphylococcus aureus Cowan 1

Tubuloreticular inclusions (TRI) and paired cisternae (PC) were induced in lymphocytes of normal individuals after incubation with Staphylococcus aureus Cowan 1. TRI were initially detected in lymphoid cells on day 2 (48-h culture). The frequency of TRI-positive cell sections on day 5 increased about twofold over those on days 2-4. On day 7, TRI were predominantly seen in lymphoplasmacytoid cells or plasmacytoid cells, with an incidence of up to 18% of sections. The regions in these cells were most extensive and anastomosed with the cisternae of adjacent well-developed rough endoplasmic reticulum (RER). TRI formation appears not to be essential for mitogen-induced B-cell differentiation to plasmacytoid cells, because pokeweed mitogen (PWM) failed to induce TRI. The diverse expressions of TRI induction between these two mitogens may be due to a difference in B-cell activation mechanisms. Paired cisternae were observed in a great majority of mitotic cells at various stages. These were encountered most frequently on day 4. PC were also seen in the PWM-stimulated culture. Our observations suggest that PC formation may be related to new formation of RER as well as to reconstruction of the nuclear envelope.     

Viruses and annulate lamellae in Friend erythroleukemia cells

Virus formation in a clone of murine undifferentiated Friend erythroleukemia cells was examined by electron microscopy. Budding C-type particles were present at the cell surface. The principal site of intracisternal particle production was in elements of rough-surfaced endoplasmic reticulum disposed about the periphery of stacks of annulate lamellae. Serial sections demonstrated that these virus-laden cisternae were in direct continuity with the annulate lamellae. In addition, intracisternal particles occurred in membranous honeycomb structures present in the cytoplasm of many cells. Viral elaboration also was associated with stacks of cisternae of endoplasmic reticulum that were devoid of ribosomes, but that were coated with an extensive and continuous layer of dense material. In some instances, the outer nuclear membrane was coated with the same dense substance. It appears that in Friend erythroleukemia cells, a very substantial portion of their cytomembranes is devoted to synthesis of intracisternal particles.     

Tubuloreticular Inclusions and Paired Cisternae Induced in Human Lymphocytes Cultured with Staphylococcus Aureus Cowan 1

Tubuloreticular inclusions (TRI) and paired cisternae (PC) were induced in lymphocytes of normal individuals after incubation with Staphylococcus aureus Cowan 1. TRI were initially detected in lymphoid cells on day 2 (48-h culture). The frequency of TRI-positive cell sections on day 5 increased about twofold over those on days 2–4. On day 7, TRI were predominantly seen in lymphoplasmacytoid cells or plasmacytoid cells, with an incidence of up to 18% of sections. The regions in these cells were most extensive and anastomosed with the cisternae of adjacent well-developed rough endoplasmic reticulum (RER). TRI formation appears not to be essential for mitogen-induced B-cell differentiation to plasmacytoid cells, because poke-weed mitogen (PWM) failed to induce TRI. The diverse expressions of TRI induction between these two mitogens may be due to a difference in B-cell activation mechanisms.

Paired cisternae were observed in a great majority of mitotic cells at various stages. These were encountered most frequently on day 4. PC were also seen in the PWM-stimulated culture. Our observations suggest that PC formation may be related to new formation of RER as well as to reconstruction of the nuclear envelope.     

Tubuloreticular Inclusions and Paired Cisternae Induced in Human Lymphocytes Cultured with Staphylococcus Aureus Cowan 1

Tubuloreticular inclusions (TRI) and paired cisternae (PC) were induced in lymphocytes of normal individuals after incubation with Staphylococcus aureus Cowan 1. TRI were initially detected in lymphoid cells on day 2 (48-h culture). The frequency of TRI-positive cell sections on day 5 increased about twofold over those on days 2-4. On day 7, TRI were predominantly seen in lymphoplasmacytoid cells or plasmacytoid cells, with an incidence of up to 18% of sections. The regions in these cells were most extensive and anastomosed with the cisternae of adjacent well-developed rough endoplasmic reticulum (RER). TRI formation appears not to be essential for mitogen-induced B-cell differentiation to plasmacytoid cells, because poke-weed mitogen (PWM) failed to induce TRI. The diverse expressions of TRI induction between these two mitogens may be due to a difference in B-cell activation mechanisms.

Paired cisternae were observed in a great majority of mitotic cells at various stages. These were encountered most frequently on day 4. PC were also seen in the PWM-stimulated culture. Our observations suggest that PC formation may be related to new formation of RER as well as to reconstruction of the nuclear envelope.     

大白鼠心脏小强荧光细胞超微结构研究

本文采用醛诱发荧光的荧光组织化学方法,首先定位小强荧光细胞,在电子显微镜下观察它们的超微结构。心脏的小强荧光细胞体积小,胞质含大量两种不同电子密度的颗粒泡。它们的线粒体丰富,每个沿核水平切面有20个线粒体;高尔基复合体发达,每组为4～7个扁囊构成;粗面内质网一般呈单独扁囊,散布在胞质。小强荧光细胞与胆碱能神经末梢形成传入性突触,相邻小强荧光细胞常形成粘合斑结构和相嵌联结。它们相邻的毛细血管,多为有孔型毛细细管。它们在相邻细胞之间、邻近血管和细胞间隙部位有胞吐现象。结果提示,这种细胞可能以内分泌或旁分泌方式,起局部调节作用。     

大鼠睾丸Sertoli细胞外质特化结构生后发育的超微结构观察

本研究采用透射电镜法,对生后1～8周和成年期大鼠睾丸Sertoli细胞外质特化结构(ES)的发育过程进行观察。结果表明,生后第1周ES处于初建阶段,质膜下见高电子密度物质聚集,并见有间断排列的内质网短池。第2周时微丝束开始出现,沿质膜下伸展,内质网池逐渐融合。第3周时微丝密度增加;相邻细胞膜间开始出现紧密连接。随生长发育ES亦逐渐完善,至生后第5周时已于Sertoli细胞基底部周缘广泛伸展。此后直至成年,其形态结构和分布未见有显著改变。本研究认为,大鼠在出生后5周内是ES的重要发育期,与血-睾屏障的形成和完善相一致。     

Fine structural localization of RNA in myeloma cells detected by the enzyme-gold method.

The ultrastructural localization of RNA in myeloma cells was studied by the RNase-gold method. Gold particles indicating the presence of RNA were observed in large numbers, particularly in the granular component of the nucleolus and periphery of the rough endoplasmic reticulum, but not in the Golgi area, mitochondria, intranuclear inclusion bodies, cytoplasmic inclusion bodies, dense bodies, or cisternae of the rough endoplasmic reticulum. In the nuclear chromatin and nucleolus, gold particles were more numerous as these structures were less mature. They were found in larger numbers also in the cytoplasm of immature cells. In plasma cells from patients with macroglobulinemia, gold particles were fewer than in myeloma cells of multiple myeloma, but there was no difference in their distribution pattern.     

Three-dimensional demonstration of the intracellular structures of mouse mesothelial cells by scanning electron microscopy

Intracellular structures of mouse mesothelial cells lining the small intestine were studied by scanning electron microscopy. Specimens were prepared by the freeze-polishing method which permitted demonstration of the attenuated thin layered organization of the intracellular structures. When the surface cell membrane had been partially turned over during the specimen preparation procedure, many pinocytotic vesicles were observed attached to the cytoplasmic side of the cell membrane. We also demonstrated the external side of the basal cell membrane on which many openings of the pinocytotic vesicles were clearly shown as those recognized on the free cell surface. Two adjacent pinocytotic vesicles often appeared fused together. The multivesicular vacuole formed by the congregation of the pinocytotic vesicles were sometimes recognized on the cytoplasmic side of the surface and basal cell membrane. On the nuclear surface, nuclear pores and polysomes were visible. From our SEM findings, we classified the rough endoplasmic reticulum into three types: type I, II and III. The type I rough endoplasmic reticulum was composed of flat cisternae with fenestration, the type II of polygonal flat cisternae without fenestration, and the type III of vesicular cisternae. Polysomal formation is evident in the type III, but less in the type I and II. All of the endoplasmic reticulum appeared connected each other forming a continuous system in the cell. Two kinds of the Golgi apparatus were recognized: a stretched type with highly extended Golgi cisternae and a shrunken type with less developed Golgi cisternae. In the latter, lots of Golgi vesicles were attached on the periphery of the cisternae, and the outermost cisterna was commonly fenestrated.     

NSF/SNAPs and p97/p47/VCIP135 are sequentially required for cell cycle-dependent reformation of the ER network

The endoplasmic reticulum (ER) has a characteristic polygonal structure with hallmark three-way junctions. In a previous paper, we reconstituted the disruption of the pre-existing ER network using mitotic cytosol from HeLa cells in streptolysin O (SLO)-permeabilized CHO-HSP cells (stably expressing GFP-HSP47). In addition, we found that interphase cytosol induced reformation of the disrupted ER network into a continuous network structure. Here, we show that the reformation of the ER network is accomplished through two sequential fusion reactions. The first process is mediated by NSF/alpha and gamma-SNAPs, and involves the generation of typical membranous intermediate structures that connect the disrupted ER tubules. A subsequent fusion is mediated by p97/p47/VCIP135, which has been shown to be required for homotypic fusion events in Golgi cisternae regrowth after mitosis. In addition, we also found that both fusion processes involve the t-SNARE, syntaxin 18.     

Intermembrane bridges within membrane organelles revealed by quick-freeze deep-etch electron microscopy

Intracellular membrane–bounded organelles, such as the endoplasmic reticulum, Golgi apparatus, and mitochondrion, possess and maintain their shape and intrinsic relationship due to the nature of their membrane organization. To reveal the membranous attachments that support these shapes and relationships, we examined various kinds of cells by quick-freeze deep-etch electron microscopy. In the cisternae of the endoplasmic reticula, we found intermembrane bridges linking opposite membranes of the cisternae. Membranes of adjoining rough endoplasmic reticulum cisternae were linked by intermembrane bridges crossing a narrow cytoplasmic gap between cisternae. Intermembrane bridges were also found in and between the Golgi cisternae and in nuclear envelopes. Three kinds of intermembrane bridges were found within mitochondria: one linking between outer and inner mitochondrial membranes and the other two spanning the intracristal space and intercristal matrix space. The presence of intermembrane bridges within membrane organelles, except for those between rough endoplasmic reticulum cisternae, was seen in all cell types examined. Intermembrane bridges within membrane organelles provide a structural basis for the membrane organization of the organelles and thus may contribute to the functional integrity of the organelles. Anat. Rec. 251:339–345, 1998. © 1998 Wiley-Liss, Inc.     

Fenestrae in the rough endoplasmic reticulum of Xenopus laevis hepatocytes

The rough endoplasmic reticulum (RER) of Xenopus laevis hepatocytes was examined by freeze-fracture and by conventional thin section electron microscopy. Much of the RER was present as stacks of cisternae at the cell periphery but, in addition, large whorls of cisternae were seen in the cytoplasm in most sections. Freeze-fracture replicas revealed fenestrae in both stacked and whorled cisternae, although the fenestrae were more numerous in the whorls. The role of these fenestrae is unknown, but such structures would facilitate access of precursors to the protein synthetic machinery in this highly metabolically active cell type. This would be particularly important in RER whorls, where the innermost cisternae would otherwise be isolated from the rest of the cytoplasm.     

Endoplasmic reticulum-Golgi apparatus relationships in the rat spermatid

The appearance of the spermatid Golgi apparatus was studied, both in thin sections of rat testes fixed in glutaraldehyde and treated with either tannic acid or ferrocyanide-reduced osmium, and in relatively thick sections (0.25-0.5 μm) of glutaraldehyde fixed tissue impregnated with uranyl acetate followed by lead and copper citrate. With any one of these three procedures, the Golgi apparatus of young spermatids examined at the Golgi and cap phases appeared as a compact hemispherical mass whose base was located next to the developing acrosomic system. The cortical region of the hemisphere was composed mainly of several stacks of saccules. The central core or medullary region contained numerous vesicular and tubular membranous profiles. Numerous cisternae of the endoplasmic reticulum (ER) were closely applied to the surface of the Golgi apparatus. In thin sections, the ER cisternae were separated from the stacks of saccules by small spherical or elongated membranous profiles. In thick sections, most of these elements formed a network of tubules, some of which being continuous with ER cisternae. Cisternae of the endoplasmic reticulum near the cis-face of the Golgi stacks also branched and traversed the cortical region of the Golgi apparatus through gaps seen between the stacks of saccules to reach the central core region. Some of these were closely applied to the trans elements of Golgi stacks although never in continuity with them. Finally, ER cisternae were found located within the stacks themselves between Golgi saccules; here the membranes of the closely apposed cisternae of the endoplasmic reticulum and Golgi saccules remained separated by a space of about 12 nm. Thus, in the spermatid, the endoplasmic reticulum was closely related with all components of the Golgi apparatus.     

Hepatitis B core and surface antigens in liver tissue. Light and electron microscopic localization by the peroxidase-labeled antibody method.

Hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg) were localized in human liver tissues by the peroxidase-labeled antibody method at the light and electron microscopic levels. Several methods of fixation, staining, and inhibition of endogenous peroxidase activity were studied. The periodate-lysine-paraformaldehyde fixative effectively preserved the tissue structure and the antigenicity of both antigens, and the peroxidase-labeled Fab' fraction of IgG penetrated well into hepatocytes. HBcAg was present in nuclei, or cytoplasm of hepatic cells, or both. In nuclei, the antigen was found both in virus-like particles of approximately 20 nm. diameter and in nuclear ground substance. In the cytoplasm, the antigen was found on membrane-bound ribosomes and free polysomes, and also in the ground substance of the cytosol near ribosomes and around nuclear membranes, especially near nuclear pores. HBcAg-positive virus-like particles were also demonstrated sparsely or in clusters in the cytoplasm. HBsAg was not present in nuclei but was found in the perinuclear space and in cisternae of endoplasmic reticulum, and on nuclear, endoplasmic reticulum, and cell membranes of hepatic cells. HBsAg-positive 25- to 30-nm. wide tubular forms, round particles (probably cross-sections of tubular forms), and a few large particles of 40 to 50 nm. diameter were seen in cisternae. Such HBsAg-positive particles were also present in the intercellular space and in Disse's space. These findings suggest that HBcAg produced on the cytoplasmic ribosomes migrates through nuclear pores to the nucleus and is assembled into core particles there. These particles may then move through nuclear pores to the cytoplasm where they are invested with HBsAg-positive membrane in cisternae of endoplasmic reticulum or as they enter the endoplasmic reticulum. These virus particles are then released together with other HBsAg-positive forms into the intercellular space by reversed phagocytosis.     

ANNULATE LAMELLAE OBSERVED IN HUMAN PROSTATIC CARCINOMA

Annulate lamellae (AL) were observed in only three out of 40 cases of human prostatic carcinoma, but not in 20 cases of benign prostatic hyperplasia and 11 cases of presumably normal prostatic tissues. AL showed the continuity with the rough endoplasmic reticulum and seemingly the nuclear membrane consisting of lamellar or concentric arrangement of stacked membranes and occasionally annular structures. In addition, annuli were detected in the rough endoplasmic reticulum near the stacked membranes which were devoid of ribosomal attachment. These results disclosed that in human prostatic tissues, AL could be only rarely detected in actively dividing cancer cells, and were seemingly the temporary transitional structures transforming from the nuclear membrane to the rough endoplasmic reticulum.     

Effects of ACTH on membranous whorls in the adrenal gland of the Mongolian gerbil

The ultrastructure of whorls of rough endoplasmic reticulum in the adrenal gland of the Mongolian gerbil (Meriones unguiculatus) was examined during and after treatment with ACTH. Whorls were loosely wound after treatment for one day and consisted of only a few paired membranes. Focal areas of increased tubular smooth endoplasmic reticulum were seen throughout the cytoplasm of the cells. Whorls disappeared altogether after three days of ACTH treatment. The structures reappeared one day after stopping the ACTH injections and seemed to enlarge progressively by addition of membranes to the periphery of the structures. Numerous vesicles and sometimes parallel cisternae of rough endoplasmic reticulum were observed in the cytoplasm of adrenocortical cells containing newly forming whorls. The whorls apparently serve as a readily available reserve of rough endoplasmic reticulum, which can transform into smooth reticulum upon stimulation with ACTH.     

Organization of the Cortical Endoplasmic Reticulum in the Squid Giant Axon

The organization of the cortical endoplasmic reticulum in the squid giant axon was investigated by rapid freeze and freeze-substitution electron microscopy, thereby eliminating the effects of fixatives on this potentially labile structure. Juvenile squid, which have thinner Schwann sheaths, were used in order to achieve freezing deep enough to include the entire axonal cortex. The smooth endoplasmic reticulum is composed of subaxolemmal and deeper cisternae, tubules, tethers and vesicles. The subaxolemmal cisternae make junctional contacts with the axolemma which are characterized by filamentous-granular bridging structures approximately 3 nm in diameter. The subaxolemmal junctions with the axolemma resemble the coupling junctions between the sarcoplasmic reticulum and the T-tubules in muscle. Reconstruction of short series of sections showed that a number of the elements of the endoplasmic reticulum were continuous but numerous separate vesicles were present as well. The morphology of endoplasmic reticulum as described here suggests that it is a highly dynamic entity as well as a Ca²⁺ sequestering organelle.     

Studies on the fine structure of ovarian steroid-secreting cells in the rabbit. I. The normal interstitial cells

In terms of their light microscopic appearance and fine structure the ovarian interstitial cells of the rabbit are typical steroid-secreting cells. They are characterized by an abundance of agranular endoplasmic reticulum, spherical mitochondria with closely packed lamellar cristae, lipid droplets which appear to arise independently of the endoplasmic reticulum, conspicuous Golgi areas, a cytoplasm containing ribosomes and variable numbers of glycogen granules. A feature of the differentiation of the cells from the theca interna of atretic follicles or the stroma is the enlargement of the multiple Golgi areas and the progressive accumulation of agranular endoplasmic reticulum, possibly by “budding” from the Golgi cisternae. “Light” and “dark” cells are observed, the latter being characterized by a more closely packed agranular endoplasmic reticulum which tends to be tubular in type, that of the “light” cell being vesicular. Electron dense material (lipid?) is found in the vesicles and tubules of the agranular endoplasmic reticulum and in the Golgi cisternae; it may indicate a role of these structures in the biosynthesis of steroidal hormone. No fine structural changes specifically associated with pregnancy were observed. Degenerative changes are common and are described. The role of the interstitial cells, especially in relation to the production of 20 alpha-hydroxyprogesterone, is discussed.     

HBV-ASSOCIATED ULTRASTRUCTURES IN THE CHIMPANZEES'LIVERS WITH EXPERIMENTAL HEPATITIS B

An electron-microscopic study was carried out using chimpanzees'livers infected with experimental hepatitis B for the elucidation of intracellular development of HBV-associated ultrastructures and extracellular release of HBV. Core particles were first detected in the nucleus of liver cells at around the time of the first seropositiveness for HBsAg, and then in the cytoplasm. Subsequently, their budding into endoplasmic reticular cisterna was seen together with other core particles in the surrounding cytoplasm. Dane-like particles were seen in the cisterna, and also extracellularly nearby a liver cell with a marked proliferation of microvilli at the onset of liver cell injury. Thereafter, core-like particles were seen within electrondense amorphous material at the site of the contact between liver cell and lymphocyte. The above sequence of features suggested us the assembly of core particles and surface envelope at the cisternal membrane of endoplasmic reticulum, and a reversed pinocytosis whereby Dane or HBV particles were released extracellularly. The filamentous structures within endoplasmic reticular cisternae, which were thought to be HBsAg, were never detected. ACTA PATHOL. JPN. 35: 1333–1342, 1985.