Ultrastructure of lipid bodies in Tilletia caries teliospores.

The ultrastructure of lipid bodies within developing, dormant, and germinating Tilletia caries (DC). Tul. (race T-16) teliospores was studied by freeze-etching and thin-sectioning techniques. When teliospores were prefixed in sodium cacodylate-buffered glutaraldehyde-acrolein for 24 h before further processing, most of the lipid bodies appeared to have a uniformly osmiophilic matrix. Some of these lipid bodies were surrounded by thin electron-dense lines that appeared to be half-unit membranes. Occasionally this membrane seemed to be absent, allowing for a direct interface between lipid and cytosol. Irregular electron-dense patterns were occasionally observed in lipid bodies of developing, dormant, and germinating teliospores. A lamellar substructure with 6- to 10-nm center-to-center spacing was visible in the electron-dense patterns at high magnifications. Irregular fracture patterns were visible in freeze-etch replicas.     

Ultrastructural pathology of leaf cells of ryegrass (Lolium multiflorum) infected with ryegrass mosaic virus.

Ryegrass mosaic virus particles and virus induced lamellar inclusions were found in mesophyll and epidermal cells of virus infected ryegrass leaves. The lamellar inclusions were occasionally found in phloem cells also. Virus particles occurred in cytoplasm, inside plasmodesmata and often in membrane bound sacs embedded in a matrix between plasmalemma and cell wall at or near plasmodesmata. Electron dense plugs protruding from plasmodesmata, finger-like cell wall outgrowths and cell wall deposits usually at plasmodesmata were also observed. Cytopathological changes in organelles in infected cells included dense deposits in the cisternae of endosplasmic reticulum and Golgi apparatus, mitochondria with electron-dense or opaque matrix, proliferating cristae and deteriorating unit membrane; and disintegrating chloroplasts.     

Nonviral Microbodies with Viral Antigenicity Produced in Cytomegalovirus-Infected Cells

Masses of homogeneous electron-dense material accumulate in the cytoplasmic inclusions of cultured fibroblasts which have been infected with "wild" and "adapted" strains of human cytomegalovirus. The substance appears to be produced by microtubular membranes and the Golgi apparatus; ultrastructural histochemistry suggests that it is not lysosomal in nature nor is it comprised of lipids or polysaccharides. The dense material "buds" into cytoplasmic tubules forming circumscribed bodies having an investing membrane similar to the viral envelope. After transport to the extracellular milieu in cytoplasmic tubules and vesicles, virions and dense bodies can be demonstrated by immune electron microscopy. The homogeneous dense body appears to be a unique product of the cytomegalovirus-infected cell which possesses a limiting membrane having antigenic determinants common with the viral envelope.     

Cytologic and ultrastructural findings of a peculiar alteration in cervical cells from patients with human papillomavirus infections

Inclusion bodies were previously found in Papanicolaou smears of patients infected by the human papillomavirus (HPV). To ascertain their origin, 12 biopsies from patients with colposcopic evidence of papillomatous lesions were studied by cytology and electron microscopy. In several instances, koilocytotic atypias and electron-dense masses included within epithelial cells were observed. Some of these epithelial cells appeared to be surrounded by other cells in a sort of concentric arrangement. The electron-dense masses were composed of intermediate filaments, vacuoles and electron-dense material. They seemed to be dyskeratotic cells. They can be compared with apoptotic bodies and may be related to a disturbance of the involucrin expression caused by the HPV infection.     

Improved demonstration of exocytotic profiles in glomus cells of rat carotid body after perfusion with glutaraldehyde fixative containing a high concentration of potassium

Extensive secretion by exocytosis was demonstrated in the glomus (type I) cells of the adult rat after perfusion of carotid bodies with a potassium-rich (high K) glutaraldehyde fixative. Similar secretory profiles were very rare with a glutaraldehyde fixative containing a low concentration of potassium (low K). The increase in the incidence of exocytotic profiles in glomus cells with the high K fixative was highly significant, whereas no statistical difference could be observed in the incidence of coated pits with the different fixatives. Exocytotic profiles were characterized by the following features: (1) they predominated in non-synaptic regions, but were occasionally observed near synapses between two glomus cells; they were not observed near synapses between glomus cells and nerve terminals; (2) extruded electron-dense material associated with coating of the cell membrane was frequent; (3) different stages of dissolution of the extruded granule material was evident. The possible role of exocytosis as a mode of secretion in the glomus cells and the characteristics of the new high K-glutaraldehyde fixative are discussed.     

种衣剂17号包衣对小麦条锈菌发育影响的超微结构研究

本研究采用电镜技术研究了种衣剂17号对小麦条锈菌发育的影响。观察结果表明,该种衣剂引起病菌和寄主细胞内发生了一系列变化。病菌菌丝和吸器内脂肪粒和液泡明显增加;菌丝壁和吸器壁呈不规则加厚;菌丝分枝处无隔膜产生或隔膜畸形;有的吸器母细胞产生的畸形入侵栓,大都不能穿透寄主细胞壁,初生吸器外间质内沉积有染色较深的物质,次生吸器可产生多个不规则分枝,但不能扩张膨大;菌丝外渗的物质可能引起寄主细胞的坏死;大多数受侵寄主细胞可分泌形成较大的胼胝质,有时寄主细胞分泌的物质可将吸器体完全包围起来。上述结果表明,种衣剂17号不仅可直接作用于条锈菌,而且也可通过影响寄主而间接地影响病菌。     

鸟类原生殖细胞的研究 Ⅰ.鸡胚生殖新月区原生殖细胞超微结构的观察

作者观察了鸡胚生殖新月区的原生殖细胞(PGC)的超微结构。PGC为圆形或椭圆形,13—16μm,有丰富的伪足和微绒毛,尚可见到相邻PGC存在桥粒样结构。细胞核为圆形、椭圆形及分叶状,并呈多处凹陷。与同期胚的其它细胞相比,胞质内细胞器相当丰富且较成熟。观察到有大量微丝。上述PGC的形态,除了细胞桥粒样结构及微丝很少见到报道外,其它特征与鸟类PGC的超微记载相一致。 作者首次观察到PGC中有一种特殊颗粒(即电子致密小体),它自核内产生,进入核周池,并借核膜破裂的方式进入胞质。这种颗粒可能就是生殖颗粒,而由该颗粒在胞质中聚集所构成的特殊高电子致密区可能就是生殖质。从而从形态学上提供了鸟类具有生殖质的证据。     

Combined Fluorescent-Antibody and Electron Microscopy Study of Marek''s Disease Virus-Infected Cell Culture

Duck embryo fibroblast (DEF) and chicken embryo fibroblast (CEF) cultures infected with Marek's disease virus were studied by combined fluorescent antibody and electron microscopy techniques. In both DEF and CEF cultures, cells containing immunofluorescent (IF) antigen also contained herpesvirus particles; conversely, cells lacking this antigen lacked herpesvirus particles. Two morphologically distinct IF antigens were detected in the cytoplasm. (i) A granular antigen in the perinuclear region was brightly stained with the conjugated antibody. This antigen was composed of a granular mass of osmiophilic material and did not contain virions. (ii) A diffuse antigen, present throughout the cytoplasm of infected cells, was less brightly stained. The area of the cell with the highest concentration of this antigen contained small vesicles, folded membranes, and fine electron-dense granules. Naked virions were occasionally seen in these areas. A diffuse nuclear IF antigen was occasionally seen in infected cells. This antigen was often separated from the nuclear membrane and the nucleolus by a clear margin. The intranuclear IF antigen was composed of a fine granular aggregate and naked herpesvirus particles which were randomly distributed throughout the nucleus. Viral capsids in antibody-treated cells were coated with fine filamentous material.     

Comparative ultrastructural study of four reticuloendothelias viruses.

The morphology and development of four members of the reticuloendotheliosis virus group were studied by transmission electron microscopy. Virions of duck spleen necrosis virus, duck infectious anemia virus, chicken syncytial virus, and reticuloendotheliosis virus strain T are sperical with a diameter of approximately 110 nm. They are covered with surface projections about 6 nm long and 10 nm in diameter. The center-to-center distance of surface projections is about 14 nm. The budding virions contain crescent-shaped electron-dense cores 73 nm in diameter with electron-lucent centers. After release of the virions the cores apparently become condensed to 67 nm in diameter. Virions were found budding at the plasma membrane and into smooth-walled, intracytoplasmic vesicles of productively infected cells. The distribution of budding reticuloendotheliosis viruses on cells appeared random over the cell surface, and occasionally aberrant multiple forms of budding virions were observed. The virions appear to resemble mammalian leukemia and sarcoma viruses more closely than avian leukosis-sarcoma viruses.     

Electron microscopy of Listeria monocytogenes-infected mouse spleen

Armstrong, B. A. (The University of Kansas, Lawrence), and C. P. Sword. Electron microscopy of Listeria monocytogenes-infected mouse spleen. J. Bacteriol. 91:1346-1355. 1966.-Mouse spleen infected with Listeria monocytogenes was observed during the acute phase of infection; 72 hr after infection, organisms were usually found within phagocytic vacuoles in the cytoplasm of macrophages. These vacuoles, which resembled phagosomes, often contained several organisms as well as varying amounts of amorphous electron-dense material, ferritin-like particles, membrane fragments, and vesicles of varying density. Breakdown of vacuolar membranes appeared to be accompanied by damage to the host cell cytoplasm. Nuclear membrane damage was occasionally observed when phagocytic vacuoles were close to the nucleus.     

鸭病毒性肠炎病毒强毒株的形态发生学与超微病理学研究

应用透射电镜和超薄切片技术,研究鸭病毒性肠炎病毒(duck enteritis virus,DEV)CH强毒株人工感染成年鸭后,病毒在宿主细胞内的形态发生及各组织器官的超微结构变化.结果表明,感染后不同时间剖杀及发病后死亡鸭的肝、肠、脾、胸腺、法氏囊等组织器官中,均观察到典型的疱疹病毒粒子.病毒主要的靶细胞为淋巴细胞、网状内皮细胞、成纤维细胞、巨噬细胞、血管内皮细胞、肠道上皮细胞、肠道平滑肌细胞和肝细胞等.DEV的核衣壳有空心型、致密核心型、双环型和内壁附有颗粒型四种形态,存在胞核和胞浆两种装配方式.病毒核衣壳可在核内获得皮层,通过核内膜获得囊膜成为成熟病毒;也可通过内外核膜进入胞浆,在其中获得皮层,然后在各种质膜上获得囊膜,最后成熟病毒释放到细胞外.伴随着病毒的复制、装配和成熟,细胞中出现多种核内和胞浆包涵体、核内致密病毒核酸颗粒、微管和中空短管以及胞浆内膜包裹的电子致密小体、双层管等病毒相关结构.超微研究表明,组织细胞有坏死和凋亡两种变化.坏死细胞肿胀甚至破裂,线粒体肿胀空泡化,粗面内质网扩张,核糖体脱落,有的细胞器甚至完全崩解,染色质或固缩或溶解.凋亡细胞则染色质聚集,胞浆凝聚深染,细胞膜上有大量空泡,并有凋亡小体形成.细胞坏死与凋亡往往同时存在,疾病发生过程中,脾、胸腺、法氏囊以及小肠固有层中的淋巴细胞凋亡数量明显增多.     

Residual bodies resulting from photosensory membrane degradation are taken up by pigment cells in the eyes of the flyLucilia sp.

Retinae of blowflies (Lucilia sp.) were exposed to light for 12 h and then investigated by routine electron microscopy. Residual bodies and multi-vesicular bodies containing electron-dense structures were found in the photoreceptor cells. These structures appeared indistinguishable from material inside the pigment granules of secondary pigment cells. The residual bodies were found in interdigitations between photoreceptor and pigment cells and were often in close contact with mitochondria. Lamellar bodies and pigment granules were also found in the extracellular space between photoreceptor and pigment cells. In a second set of experiments, a membrane-impermeable reagent [sulfosuccinimidyl-6-(biotinamido) hexanoate] that should covalently biotinylate the surface of the photosensory membrane was introduced into the ommatidial cavity. The marker was detected, 4 h after application, inside the ommatidial cavity, on the rhabdomeric microvilli, and on residual bodies inside the photoreceptor cells, by streptavidin-gold binding on ultrathin sections. After 6 h of exposure to the reagent, pigment granules of the adjacent pigment cells were also labeled. The results suggest that the photosensory membrane is taken up and degraded together with the marker. Residual bodies resulting from this degradative process may thus be transported into the pigment cells; eventually material originating from photosensory membrane degradation may then be involved in pigment granule synthesis.     

SEASONAL CHANGES IN THE APICAL ZONATION AND ULTRASTRUCTURE OF COASTAL DOUGLAS FIR SEEDLINGS (PSEUDOTSUGA MENZIESII)

The apical meristems of one-year-old container-grown seedlings of coastal Douglas fir were studied in two years during embryonic shoot development, dormancy, and dormancy release by light and electron microscopy. Apical zonation was evident at all times but prominence of some zones varied. Vacuolation was an important zone-characteristic and was not an artifact created by lipid extraction. During late summer and fall the plasma membrane was relatively smooth, ER not abundant, nuclear membranes irregular, and lipid bodies sparse. Numerous autophagic vacuoles occurred in apical cells. These diminished after bud scale initiation was completed in September and reappeared again in midwinter. Maximum starch accumulation was in the fall then it decreased during the winter and remained low during cold storage. The number of lipid bodies gradually increased in late fall and was large in winter. A single night of –1 C caused an increase in the number of lipid bodies. Plastids contained electron-dense material which accumulated further under subfreezing temperatures and eventually appeared to be released during winter into the cytoplasm and arranged into small globules along the cisternae of the ER. Granular protein bodies were observed at this time as well as deposits of electron-dense material on the outer surface of the plasma membrane and in cell walls. During winter, the plasma membrane became convoluted, short cisternae of the ER abundant, the nuclear membranes evenly separated, and nucleolar components aggregated. At the end of dormancy, ribosomes and starch grains became very abundant. Most lipid bodies diminished by budbreak.     

Mast cell response during the early phase of tuberculosis: an electron-microscopic study.

Guinea pig lungs were infected with Mycobacterium tuberculosis by intratracheal route and examined under electron microscope to investigate the morphological alterations of the organisms, if any, and the response of the host tissue. The bacilli showed no changes in their morphology, while the host tissues revealed several cells containing many electron-dense intracytoplasmic granules. These cells were predominantly seen during the 1st week of infection. The electron-dense bodies of these cells may be the ones observed by earlier workers and suggested to be the altered forms of tubercle bacilli. The present investigation, however, revealed them to be the granules of the mast cells. These cells were observed to respond to tuberculous infection during the first few days by appearing in large numbers crowded with intracytoplasmic granules and soon disintegrating as the result of subsequent degranulation. The above observation is presented and its significance discussed.     

Fine Structure of Oocyst Transformation and the Sporozoites of Leucocytozoon dubreuili*

SYNOPSIS. The sporogonic stages of Leucocytozoon dubreuili in the midgut and salivary glands of the simuliid vectors was studied by electron microscopy. Young uninucleate oocysts have a pellicle that initially resembles that of the ookinetc. Numerous electron-dense bodies and microtubules in the peripheral cytoplasm may be involved in the formation of the cyst wall. The dense bodies appear to give rise to the amorphous material of the wall. The tubules which run circumferentially beneath the oocyst's boundary probably serve as a skeletal support for the cell surface during deposition of the wall material. A subcapsular “space” which provides area for expansion of the developing sporozoites is formed in early multinucleate oocysts. The subcapsular “space” appears to be formed through a condensation of the peripheral cytoplasm, resulting in an osmotic gradient across the oocyst's limiting membrane. Consequently water diffuses out, creating a fluid-filled space. Sporozoite formation begins with localized thickenings on the oocyst's limiting membrane. Subsequent extension of the thickened regions into the subcapsular “space” marks the onset of sporozoite budding. The process is highly synchronized, and culminates with the production of up to 150 sporozoites about the sporoblastoid body. The structure of sporozoites from mature oocysts and of the salivary glands of the vector is basically similar, although salivary gland sporozoites are more elongate and have numerous electron-dense micronemes. The paired rhoptries in the latter sporozoites are more elongate and uniformly electron-dense than in oocyst sporozoites.     

Ultrastructural studies of microgametogenesis and macrogametogenesis of Eimeria truncata of the lesser snow goose

Microgamonts and macrogamonts of Eimeria truncata were observed in renal epithelial cells of collecting tubules and ducts and occasionally in macrophages of experimentally infected lesser snow geese (Anser c. caerulescens) beginning 8.5 days post inoculation. Intraparasitophorous vesicles in parasitophorous vacuoles of both types of gamonts appeared to originate in host cell cytoplasm and enter gamonts through micropores by budding of plasmalemma or by pinocytosis. Within the parasite's cytoplasm, the vesicles were broken down in Golgi-associated vacuoles. The surfaces of microgamonts were highly invaginated to facilitate extrusion of numerous microgametes. Formation and maturation of microgametes were similar to those of other eimerian species. Each microgamete had two flagella, a mitochondrion, and a peculiarly shaped electron-dense nucleus that was oval anteriorly in cross section and somewhat dumbbell-shaped posteriorly. A longitudinally arranged inner membrane complex lay between a portion of the mitochondrion and the plasmalemma. About five subpellicular microtubules extended the length of the microgamete body. Macrogametogony differed little from that described in other eimerian species. Type 1 wall-forming bodies (WFB) formed in Golgi complexes early in macrogametogony, and type 2 WFB formed in cisternae of endoplasmic reticulum in intermediate stages of macrogamont development.     

Intramembrane changes occurring during maturation of herpes simplex virus type 1: freeze-fracture study.

During the maturation of two strains of herpes simplex virus type 1 (VR3 and Patton), intramembrane changes were detected with the freeze-fracture technique in the viral envelope and the infected cell plasma membrane, and these changes were compared with data obtained from thin sections. Regardless of the strain, the inner leaflet of the viral envelope of extracellular virions was characterized by a density of intramembrane particles (IMP) three times larger than the host nuclear and plasma membrane. Addition of IMP, which probably represent virus-coded proteins, was detected in the viral envelope only after budding from the nuclear membrane, whereas it occurred during envelopment of capsids at cytoplasmic vacuoles. Fused membranes also showed one of their fracture faces covered with a high density of IMP similar to that of the mature virion envelope. The internal side of the membrane leaflet bearing these numerous particles was always characterized by the presence of an electron-dense material in thin sections. In addition, the plasma membrane of fibroblasts and Vero cells showed strain-specific changes: patches of closely packed IMP were observed with the VR3 strain, whereas ridges almost devoid of IMP characterized the plasmalemma of cells infected with the Patton strain. These intramembrane changes, however, were not observed as early as herpes membrane antigens. Thus, application of the freeze-fracture technique to herpes simplex virus type 1-infected cells revealed striking structural differences between viral and uninfected cell membranes. These differences are probably related to insertion and clustering of virus-coded proteins in the hydrophobic part of the membrane bilayer.     

Electron microscopy of vesicular-arbuscular mycorrhizae of yellow poplar. II. Intracellular hyphae and vesicles.

Intracellular hyphae and vesicles in mycorrhizal roots of yellow poplar were examined by electron microscopy. An investing layer of host wall material and cytoplasm enclosed the endophyte within the cells. Young developing hyphae contained abundant cytoplasm and few vacuoles. As hyphae matured, they became highly vacuolated and accumulated carbohydrate (glycogen) and lipid reserves. Mature vesicles were engorged with lipid droplets, possessed a trilaminate wall and were also enclosed by host wall material and cytoplasm. Compared with uninfected cells, infected cortical cells showed an increase in cytoplasmic volume, enlarged nuclei, and a reduction of starch reserves. Host nuclei were always proximal to the hyphae during hyphal development and deterioration. While other cytoplasmic components of infected and uninfected cells were comparable large electron-dense bodies occurred in vacuoles of most cells containing hyphae. Deterioration of intracellular hyphae occurred throughout the samples examined. Septa separated functional and degenerating portions of the hyphae. Hyphal deterioration involved degeneration and ultimate disappearance of fungal cytoplasm as well as collapse of hyphal walls. Based on these observations, the authors hypothesize that deterioration of the endophyte may release significant quantities of mineral nutrients, via hyphal contents, which are absorbed by the host.     

Microfibril formation in chick notochordal cells

The central parts of the chick notochord at Hamburger and Hamilton's stages 20–22 were investigated by electron microscopy. Electron-dense bodies of various sizes and shapes and bounded by a limiting membrane were found in the central cells of the notochord. These dense bodies contained fibrous material or microfibrils which ranged from 120 to 600 Å in diameter. The large microfibrils often exhibited a typical repeating period with an interval of about 320 Å. These dense bodies were always located near the cell membrane, which is rough or irregular in the central parts of the notochord at these stages. The fibrous core material of the dense body frequently shows striking similarities to amorphous fibrous material in the intercellular space of the central parts of the notochord, where they are situated at a considerable distance from the perinotochordal sheath space. From these results, it seems reasonable to suggest that the central cells as well as the peripheral cells of the notochord are capable of forming microfibrils similar to those observed in the perinotochordal sheath space.Moreover, they may play an important role in the total fibrillogenesis of the notochord.     

Phagotrophy and two new structures in the malaria parasite Plasmodium berghei

Blood collected from rats infected with Plasmodium berghei was centrifuged and the pellet was fixed for 1 hour in 1 per cent buffered OsO(4) with 4.9 per cent sucrose. The material was embedded in n-butyl methacrylate and the resulting blocks sectioned for electron microscopy. The parasites were found to contain, in almost all sections, oval bodies of the same density and structure as the host cytoplasm. Continuity between these bodies and the host cytoplasm was found in a number of electron micrographs, showing that the bodies are formed by invagination of the double plasma membrane of the parasite. In this way the host cell is incorporated by phagotrophy into food vacuoles within the parasite. Hematin, the residue of hemoglobin digestion, was never observed inside the food vacuole but in small vesicles lying around it and sometimes connected with it. The vesicles are pinched off from the food vacuole proper and are the site of hemoglobin digestion. The active double limiting membrane is responsible not only for the formation of food vacuoles but also for the presence of two new structures. One is composed of two to six concentric double wavy membranes originating from the plasma membrane. Since no typical mitochondria were found in P. berghei, it is assumed that the concentric structure performs mitochondrial functions. The other structure appears as a sausage-shaped vacuole surrounded by two membranes of the same thickness, density, and spacing as the limiting membrane of the body. The cytoplasm of the parasite is rich in vesicles of endoplasmic reticulum and Palade's small particles. Its nucleus is of low density and encased in a double membrane. The host cells (reticulocytes) have mitochondria with numerous cristae mitochondriales. In many infected and intact reticulocytes ferritin was found in vacuoles, mitochondria, canaliculi, or scattered in the cytoplasm.