Scanning Electron Microscope Observations of Amoeba proteus During Phagocytosis*

SYNOPSIS. Phagocytosing Amoeba proteus at different stages of forming foodcups have been observed by scanning electron microscopy. A nonphagocytosing ameba is characterized by dorsal and lateral ridges running longitudinally over the posterior half of the cell and its attachment to the substrate over small areas. When stimulated by prey organisms, the ameba loses polarity and ridges, and adheres to the substrate more firmly over a wider area of contact. Then it forms broad pseudopods to surround its prey and this results in the formation of foodcups. The surface of all amebae is covered with small projections, and membranous blebs are often seen on the surface of phagocytosing organisms.     

A Study of the Structure and Gliding Movement of Gregarina garnhami

SYNOPSIS The structure and gliding movement of Gregarina garnhami Canning, a eugregarine found in the midgut of the desert locust, Schistocerca gregaria , have been studied by light microscopy and transmission and scanning electron microscopy (EM). Ultrastructural studies revealed that the cytoplasm of G. garnhami is separated from the epicyte folds by a basal lamina. The pellicle consists of 3 membrane layers. At the tips of the epicyte folds there are 2 sets of longitudinally oriented filaments. An ectoplasmic network is present in the ectoplasm and the endoplasm contains numerous paraglycogen granules. The effect of cytochalasin B on G. garnhami was studied. Examination of scanning EM preparations of gliding and stationary gregarines yielded inconclusive results. In some instances the epicyte folds were thrown into waves; in others the folds were straight, regardless of treatment before fixation. Gregarina garnhami glides through its environment without any apparent deformation in shape. As it moves, a mucus trail is left behind it. Phase-contrast observations were made of centrifuged gregarines in which the endoplasm was displaced. Centrifuged gregarines continued to glide. Displacement of the endoplasm allows visualization of the epicyte folds in gliding animals. No lateral waves were seen in the epicyte folds of gliding centrifuged animals.     

Conjugation in the Hypotrich Ciliate,Paraurostyla weissei (Stein): A Scanning Electron Microscope Study*

SYNOPSIS. Conjugation in Paraurostyla weissei has been investigated by scanning electron microscopy. In the course of conjugation, one member of each conjugating pair is resorbed. An organism that is being resorbed always lies to its partner's left and is always fused to its partner's oral region. A mechanism for the development of this asymmetry is proposed, based on the asymmetry of individual Paraurostyla. After resorption is complete, exconjugants enter a rounded, nonmotile stage which lasts several days. Exconjugants at this stage have been compared with cysts and have been found to be dissimilar.     

Three-Dimensional Structure of Macronuclei from Paramecium Determined by Scanning Electron Microscopy*

SYNOPSIS. Macronuclei of Paramecium primaurelia were isolated and examined by scanning electron microscopy. These nuclei consisted of a closely packed array of chromatin bodies measuring ～ 0.2 μm in diameter. We estimated there were ～ 30,000 such bodies/macronucleus, 20 times more than the number of unit genome equivalents. This suggests that a unit genome is physically shared by several chromatin bodies.     

大鳞副泥鳅鳞片表面结构的扫描电镜观察

对大鳞副泥鳅的鳞片作了扫描电镜观察。结果表明,大鳞副泥鳅具圆鳞;基区、侧区和顶区均具有辐射沟及环沟,二者交织成网状,将鳞片分割成块状,可增加鳞片的柔软度;次级辐射沟发出部位可作为确定年轮的主要依据。     

东方沙蟒显微皮纹结构与功能

对隶属蟒科的东方沙蟒唇鳞的光学显微结构和扫描电镜下的超微结构的观察发现了类似小窝的结构,可能是原始的鳞片感受器官;对鳞片感受器的大小做了测量;同时观察了头部其他鳞片和身体中部背鳞和腹鳞的显微皮纹结构。所有鳞片的角皮层细胞平坦,没有大的表面特征结构,除了后缘齿状结构、微孔和窄而短的边界。考虑到穴居种类减少反光不是主要的选择因子,而主要选择是减少摩擦和清除污物,显微皮纹特征很好地符合这一假说。不同部位鳞片的差异主要表现在角皮层细胞的形状和的大小,微孔的有无,细胞后缘齿状结构的有无和大小以及细胞边界重叠的程度。首次描述了鹅卵石样多孔细胞这一微饰类型。     

Scanning Electron Microscopy of the Cortex of the Ciliate Stentor coeruleus. A View from the Inside*

SYNOPSIS. A microdissection procedure was developed which permits the viewing of the inside surface of the cortex of Stentor coeruleus with scanning electron microscopy. Parallel bands of myonemes cover the entire inner surface of the cortex. The myonemes of the stalk region are ribbon-shaped and lack cross connections. The myonemes of the anterior cortex are flattened against the surface and are interconnected by an extensive system of cross branches. The inner surface of the frontal field is covered with a regularly cross-branched myoneme system which follows the curved pattern of frontal field kinety. The observed branching patterns and shapes of the myonemes support the hypothesis that they cause contraction of the cell. The membranellar root system was examined. Each membranellar root makes a 90° counterclockwise twist along its vertical axis (viewed from the inside) as it descends into the cell. The outer edge of each root fuses with the inner edge of the adjacent one, forming a continuous fiber sheet linking the roots together.     

Scanning Electron Microscope Studies of Steinernema anomali Kozodoi, 1984

This paper presents SEM micrographs of portions of the male, female, and infective-stage juvenile of Steinernema anomali. Included are micrographs of the cephalic and caudal region, spicules, and gubernaculum of the male, the cephalic and vulval region of the female, and the cephalic region of the infective-stage juvenile. Males have six labial and four prominent cephalic papillae and small amphids. There are 11-14 pairs and one single genital papillae; of these, 6-9 pairs are preanal and subventral, one pair preanal, lateral, one pair adanal, and three pairs postanal. Spicules have a short head, a long blade, and a reduced shaft. The distal end is enlarged and bears a dorsal aperture. Gubernaculum much shorter than spicules; cuneus of gubernaculum short and bifurcate anteriorly. Females have six labial and four cephalic papillae and small amphids. Vulva with a thickened posterior lip. Infective juveniles have a smooth head, prominent amphids, and four cephalic papillae. Labial papillae, if present, are not evident.     

Scanning Electron Microscopy of Tintinnopsis parva: Studies on Particle Accumulation and the Striae*

SYNOPSIS. Lorica building was studied experimentally for Tintinnopsis parva Merkle, an agglutinated tintinnid. This species incorporated either siliceous or Ca-rich particles. Evidence of agglutination was seen within 30 min after the addition of particles to cultures of the protozoa. Fully agglutinated loricae were produced by the proter; partially incrusted loricae attributed to an opisthe were also recovered. The cytoplasmic evaginations of unknown function called striae were seen in the scanning electron microscope in better relief than ever before. They may provide the mechanism whereby the enclosed capsules are brought into contact with prey organisms.     

Chronologie des Modifications Ultrastructurales au Cours de la Croissance de Gregarina blaberae*

SYNOPSIS. In an ultrastructural study the development of the sporozoite as well as the growth and development of the trophozoite of Gregarina blaberae were followed in the course of experimental infections of larvae of the cockroach Blaberus craniifer. The spectacular growth involved the transformation within 18 days of the sporozoite, measuring 15 × 1 μm, to a cephaline—trophozoite affixed to the intestinal epithelium—of 250 μm length and 65 μm diameter. The sporozoite's ultrastructure is not different from that of sporozoites of other Sporozoa studied to date—the conoid and dense bodies are present. The pellicle consists of 3 membranes, but there are some interruptions in the internal membrane complex. The first dictyosomes are formed from the nuclear envelope. The migration of the nucleus and of the dense bodies, followed by the regression of all the structures characteristic of the sporozoites, and the establishment of a cortical zone that comes to cover the epimerite, take place within 48 hr after infection and mark the transformation of the sporozoite into the trophozoite. Development of the cephaline involves the formation of the epicytic folds, which occurs at the base of the deutomerite, starting on the 3rd day of development. A regular system of longitudinal or epicytic folds is formed over the entire surface of the gregarine. On the 4th and 5th days of development, a vacuolar system and a chondriome become differentiated in the epimerite, while a fibrillar septum separates the protomerite from the deutomerite. The next stage, starting on the 6th day, is characterized by distribution of polysaccharide reserves between these 2 segments. The model studied allows us to determine the role of the epimerite in the parasite's nutrition, as well as the development of the chondriome and of the cortical membranes in the course of the vegetative growth phase of the cephaline gregarine.     

Scanning Electron Microscopy of Stomatogenesis Accompanying Conjugation in Euplotes aediculatus*

SYNOPSIS. The succession of morphologic changes in the feeding apparatus (peristome) accompanying conjugation and postconjugant development in the hypotrich Euplotes aediculatus has been examined by scanning electron microscopy (SEM). The details of stomatogenesis inferred from earlier light-microscopic studies of silver-stained preparations have been confirmed and extended. The elaborate peristome is the dominant surface feature of vegetative Euplotes. In conjugation, the ciliates are joined in their peristomial regions; as the conjugants separate, the old feeding apparatus is seen to be disrupted and partially resorbed. In its place is the crescent-shaped primordium of a new peristome, which develops as part of a general cortical reorganization. This primordium expands anteriorly, unfurling a new crown of ciliary membranelles that soon replaces the remaining preconjugant membranellar band. The resulting “exconjugant peristome'’is characterized by a greatly reduced number of adoral membranelles and the absence of paroral membranelles, buccal cavity, and cytostome. Exconjugants thus cannot feed for 2–3 days, until the missing peristomial components are replaced. This occurs by means of a 2nd cortical reorganization, during which new membranelles, developing from another peristomial rudiment, are added directly to the abbreviated exconjugant set. A new buccal cavity is concurrently sculpted as the primordial depression enlarges, and the cells can resume feeding sometime during the 4th day after separation. The implications of this mode of stomatogenesis and the nonfeeding condition are discussed, as are the advantages of SEM for studies of ciliate morphogenesis.     

Sphaeromyxa maiyai sp. n. (Protozoa: Myxosporidea), Coelozoic Parasite of the Pacific Tomcod,Microgadus proxiimus*

SYNOPSIS. Sphaeromyxa maiyai sp. n. (Myxosporidea: Myxiidae) is described from the gall bladder of the Pacific tomcod Microgadus proximus Girard, from Newport, Oregon. The plasmodial stage is discoid averaging between 1 and 2 cm. The spore averages 27.6 × 5.6 μm in breadth, with pyriform polar capsules measuring 9.3 × 3.7 μm. Scanning electron microscopy reveals the presence of numerous longitudinal striations.     

Ultrastructural and Cytochemical Observations on Sporogenesis of Myxobolus sp. (Myxosporida: Myxobolidae) from the Common Shiner Notropis cornutus*

SYNOPSIS. The structure and cytochemistry of spores of Myxobolus sp. from plasmodia which occur in the gill filaments of the common shiner Notropis cornutus were studied by light microscopy and by scanning and transmission electron microscopy. The thin-walled valves of the pyriform spores are thickened in the lateral sutural and apical regions. Mucous material is associated predominantly with the posterior end of many spores. The plasmodium is surrounded by a syncytial wall bounded by 2 membranes. Pinocytotic channels are formed by the inner membrane and numerous dense vesicles are pinched off at the distal ends of the channels. Sporogenesis is initiated by the envelopment of one vegetative cell by another. The larger, enveloped cell divides to form a disporous pansporoblast, which contains 2 pairs of capsulogenic and valvogenic cells and 2 binucleate sporoplasm cells. Each capsular primordium and connecting external tubule gives rise to a polar capsule which houses a helically coiled polar tubule. The apical end of each polar capsule is plugged by a stopper. The valvogenic cells surround the capsulogenic and posteriorly situated sporoplasm cells to form the spore valves. Iodinophilic (glycogen) inclusions were not seen in spores stained with iodine or Best's carmine. A darkly stained band was observed around the posterior region of most spores stained with Best's carmine. In the electron microscope large aggregates of β glycogen particles were seen in the cytoplasm of sporoplasm cells in mature spores.     

一种用于观察纤毛虫表膜下结构的扫描电镜样品制备新方法

该实验摸索出通过扫描电镜观察纤毛虫表膜下三维结构的新方法:用适当浓度的KMnO_4作为固定剂,固定虫体细胞表膜,调整固定液的渗透压使细胞在低渗溶液中胀破、细胞质溶出,表膜剥落下来、内外翻转,经脱水、冷冻干燥、喷金后,在扫描电镜下对爽口虫(Climacostomumsp.)、尾草履虫(Paramecium caudatum)及拟尾柱虫(Paraurostyla weissei)的表膜下结构进行了观察。结果表明:利用此方法能够观察到表膜下层次分明而又清晰的三维立体构象。此方法可为纤毛虫表膜及其它细胞质膜的研究提供可借鉴的样品制备新方法。     

Ultrastructure of Red-Sore Lesions on Largemouth Bass (Micropterus salmoides): Association of the Ciliate Epistylis sp. and the Bacterium Aeromonas hydrophila*

SYNOPSIS. Epizootic outbreaks of red-sore disease in several reservoirs in the southeastern United States have been reported to cause heavy mortality among several species of fish having sport and commercial value. The etiologic agent is said to be the peritrich ciliate Epistylis sp.; secondary infection by the gram-negative bacterium Aeromonas hydrophila produces hemorrhagic septicemia which results in death. However, in recent studies on the largemouth bass Micropterus salmoides, Epistylis sp. could be isolated from only 35% of 114 lesions from 114 fish, while A. hydrophila was found in 96% of the same lesions. Transmission and scanning electron microscopy of lesions associated with red-sore disease indicate that neither the stalk nor the attachment structure of Epistylis sp. have organelles capable of producing lytic enzymes. Since other investigators have shown that A. hydrophila produces strong lytic toxins, and in absence of evidence to the contrary, it is concluded that Epistylis sp. is a benign ectocommensal and that A. hydrophila is the primary etiologic agent of red-sore disease.     

Scanning Electron Microscope Study of the Root-knot Nematode (Meloidogyne incognita) on Tomato Root

This study examines the types of structural information that can be gained by utilizing the scanning electron microscope (SEM) and a cryofracture technique to examine the host-parasite interaction. Roots of tomato, Lycopersicon esculentum cv. Marglobe, were cultured aseptically and inoculated with the root-knot nematode, Meloidogyne incognita. Twenty-four hours to four weeks after inoculation, developing galls were removed from the cultures and processed for SEM observation. The cryofracture technique was used to reveal internal structural features within the developing galls. The results illustrate structural details concerning penetration of the roots, differentiation of syncytia, and development of the nematodes beginning with the second-stage larvae and ending with adult egg-laying females.     

Ultrastructure and distribution of sensilla on the antennae of female fig wasp Eupristina sp. (Hymenoptera: Agaonidae)

In the species‐specific and obligate mutualism between the fig (Moraceae: Ficus spp.) and its pollinator (Hymenoptera: Agaonidae), the continuity of lifecycle of both partners completely depends on the female pollinator's ability to detect receptive figs. To better understand the chemical location mechanism, we examined the antennae and their sensilla of the female fig pollinator Eupristina sp. using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The antennae of female Eupristina sp. are geniculated, and in total, there were seven types of sensilla found on the antennae: two types of multiporous placoid sensilla (type 1 is sausage‐like and type 2 is rounded), sensilla trichodea (ST), basiconic sensilla (BS), chaetica sensilla (ChS), coeloconic sensilla (CoS), and one specialized sensillum classified as sensillum obscurum (SO). We described external morphology, abundance, distribution, ultrastructure and discussed putative functions. We inferred from their ultrastructures as chemoreceptors that two types of multiporous placoid sensilla, BS and CoS, were innervated by sensory neurons. The aporous type ST, ChS, and SO were not innervated by dendrites which may function as mechanoreceptor/proprioceptor. These results were also discussed in relation to the interaction between Eupristina sp. and its host fig.     

小地老虎雄蛾触角感受器的扫描电镜观察

利用扫描电镜观察了小地老虎雄蛾触角感受器的种类、形态和分布.结果表明, 小地老虎雄蛾触角为双栉状(端半部为丝状),由1节柄节、1节梗节和82～92节鞭节组成.在触角上分布有毛形感器、刺形感器、鳞形感器、腔锥感器、腔形感器、 耳形感器、B(o)hm's氏鬃毛7种感受器,其中毛形感器数量最多.     

利用激光扫描共聚焦显微镜研究植物细胞发育形态学变化

通过激光扫描共聚焦显微镜,利用不同种类(波长)的激光研究植物细胞发育形态学变化。结果表明,利用紫外激光(351 nm)扫描可以清楚地观察到拟南芥叶片表皮细胞的形态及其变化,在已分化的叶片表皮上可观察到包括“铺垫”表皮细胞(epidermal pavement cells)、气孔保卫细胞(guard cell)、气孔伴胞(subsidiarycells)、表皮毛细胞(trichomes)和表皮毛的足细胞(socket cells)等多种形态不同的细胞种类;利用蓝光激光(488nm)辅助曙红浅染,可清晰地显示出拟南芥根生长区内部的各种原始细胞,包括静止区(quiescent center)细胞、皮层/内皮层原始细胞(cortex/endodermal initial cell)、表皮/根冠原始细胞(epidermal/root cap initial cell)和中柱/根冠原始细胞(columella/root cap initial cell)等。利用双光子激光(800 nm)连续扫描30 s可以诱发叶绿体产生自发荧光,并可观察到叶绿体在叶肉细胞中的运动轨迹。结果说明激光扫描共聚焦显微镜在植物细胞形态及发育研究上具有独特的功能。     

Eimeria diminuta sp. n. from the Ceylon Jungle Fowl,Callus lafayettei*

SYNOPSIS. Eimeria diminuta sp. n. is described from the Ceylon jungle fowl Gallus lafayettei. Its sporulated oocysts are 16.5 (16–17.5) × 14.5 (13.5 × 15.5) μm. The species produces patent infections in domestic fowl.