ELECTRON MICROSCOPIC STUDIES ON THE INDIRECT FLIGHT MUSCLES OF DROSOPHILA MELANOGASTER : I. Structure of the Myofibrils

The myofibrils in Drosophila have thick and thin types of myofilaments arranged in the hexagonal pattern described for Calliphora by Huxley and Hanson (15). The thick filaments, along most of their length in the A band, seem to be binary in structure, consisting of a dense cortex and a lighter medulla. In the H zone, however, they show more uniform density; lateral projections (bridges) also appear to be absent in this region. The M band has a varying number of granules (probably of glycogen) distributed between the myofilaments. The myofilaments on reaching the Z region appear to change their hexagonal arrangement and become connected to one another by Z filaments. The regular arrangement of the filaments found in most regions of the fibrils is not seen in the terminal sarcomeres of some flight muscles; the two types of filaments appear to be intermingled in an irregular pattern in these parts of the fibrils. The attachment of myofibrils to the cuticle through the epidermal cells is described.     

STUDIES ON THE CROSS-STRIATION OF THE INDIRECT FLIGHT MYOFIBRILS OF THE BLOWFLY CALLIPHORA

1. The cross-striation in the indirect flight myofibrils of Calliphora has been studied by phase contrast and polarised light microscopy. The band pattern at rest-length has been determined in flies killed in osmium tetroxide vapour while their wings remained in the resting position. All other observations have been made on unfixed fibrils. Although length changes in situ are probably very slight (about 2 per cent), isolated fibrils, by treatment with crude muscle extract or with ATP, can be induced to elongate to 104 per cent rest-length, or to shorten by 8 per cent but no more. Over the range 98 to 104 per cent rest-length, experimentally induced length changes are reversible. The fibrils can also be stretched beyond 104 per cent rest-length, but the process is irreversible. During the course of glycerol extraction the fibrils elongate to 104 per cent rest-length. 2. The changes in band pattern observed over the range 104 to 92 per cent rest-length are qualitatively the same as the changes observed over a wider range (about 130 to 40 per cent rest-length) in the skeletal myofibrils of rabbits. The earlier stages of shortening appear to be effected by retraction of the I bands into the A bands where they fill up the H zones. No evidence has been found that any changes in band pattern are due to a migration of the A substance. 3. Two components of the sarcomere can be extracted from it and a third component remains behind. These three components, which have also been demonstrated in skeletal myofibrils of the rabbit, where they behave in the same way, are: (a) the A substance which does not change its position as the fibril changes its length, and which can be extracted by the same procedures as remove myosin (shown elsewhere to be the A substance) from rabbit fibrils; (b) a material which extends from the Z lines to the borders of the H zone and which moves inwards during contraction and outwards during elongation; it can capture rabbit myosin from solution and form with it a contractile system, and it is thought to be actin; (c) a "backbone" or stroma bearing Z and M lines. 4. Since all these features of the cross-striation are the same in the insect fibrils as in rabbit fibrils, it is considered very probable that the sarcomere is similarly organised in both types of muscle and contracts by essentially the same mechanism.     

ELECTRON MICROSCOPIC STUDIES ON ACHROSOME FORMATION IN THE COCKROACH, BLATTELLA GERMANICA

The development of achrosomes in spermiogenesis of Blattella germanica was studied by electron microscopy. Achrosomes consist of an achrosomal vesicle originating from Golgi vesicles and an axial rod composed of fine fibrils.
The achrosomal vesicle, formed at the mature face of the Golgi body, migrates to the anterior of the nucleus, where it later becomes the front structures of sperm head. After attachment to the nucleus, the achrosomal vesicle changes from a round to a tapering shape, passing through a coneshape phase. During these changes, the axial rod develops in the hollow formed by indentations of adjacent parts of the achrosomal vesicle and the nucleus.
The cisternae of the Golgi body concerned with formation of the achrosomal vesicle, are made by pinching off small vesicles from both the ER and the nuclear envelope.     

紫彩血蛤鳃的组织化学和扫描电镜研究

紫彩血蛤（Ｎｕｔｔａｌｌｉａｏｌｉｖａｃｅａ）的鳃上皮细胞核多为椭圆形,核内染色体呈丝状;结缔组织细胞的核多为圆形,部分核内有块状Ｆｅｕｌｇｅｎ阳性颗粒,ＲＮＡ在鳃丝上皮细胞最丰富,有的形成直径０．５２μｍ的颗粒,结缔组织和鳃丝上皮细胞内均有直径０．６３μｍ左右的ＰＡＳ阳性颗粒,吞噬细胞呈极强的ＡＮＡＥ阳性,鳃丝上皮细胞呈较弱的阳性。ＡＣＰ和ＡＫＰ在吞噬细胞和外缘上皮细胞中的活性较强,其它部位较弱     

银合欢根瘤细胞的光学显微镜和电子显微镜研究

银合欢接种根瘤菌形成根瘤后,应用光镜和电镜技术观察。银合欢根瘤由分生组织细胞、皮层组织细胞、维管束系统和侵染细胞区域四个不同部分组成。根瘤菌借助于侵染线侵染细胞,释放进入宿主细胞质中,转变成固氮类菌体。最初每个包被膜内只含单独的类菌体,随后较老的侵染细胞中,每个包被膜内含有一个以上的类菌体。因此,成熟根瘤的侵染细胞可见有2~5个类菌体群集包被膜里,并且明显地累积PHB物质,显示电子染色透明颗粒。本文还讨论了上述变化的意义与银合欢根瘤细胞结构和功能的关系。     

ELECTRON MICROSCOPIC STUDIES ON THE DEVELOPMENT OF VESICULAR STOMATITIS VIRUS IN KB CELLS

The development of vesicular stomatitis virus in KB cells was studied by electron microscopy. Sections of infected cells were made 1, 4, 7, 10, and 20 hours after inoculation of the cell cultures, and at the same intervals the supernatant fluid was assayed for virus titer by the plaque test in chick embryo cells. At 10, 14, and 20 hours after inoculation, virus rods were observed attached to cytoplasmic membranes, inside cytoplasmic vacuoles, and attached to the membranes delimiting these vacuoles; they were also found on the surface membrane of the cells. Besides the rods, spherical particles of different sizes and shapes were seen. The possibility that these structures are related to the development of virus rods is discussed. A similarity was noted between the site of maturation of vesicular stomatitis virus rods and that of some other arbor viruses.     

ELECTRON MICROSCOPIC STUDIES ON THE BEHAVIOR OF GLYCOGEN PARTICLES DURING OOGENESIS IN THE SEA URCHIN

The behavior of glycogen particles during oogenesis in the sea urchin was studied by electron microscopy. Before the beginning of oogenesis the nurse cells include many glycogen particles, which are spherical or multiangular in shape and about 600 A in diameter, lying within the vesicle of the large granules and also in the cytoplasm among the granules. There are few glycogen particles in the spaces among the oocytes and the nurse cells. At the early stage of oogenesis the limiting membrane of the large granule breaks locally and the glycogen particles in the vesicle are dispersed into the cytoplasm. The plasma membrane of the nurse cell also breaks in places and glycogen particles are spread throughout the intercellular space. At the beginning of vitellogenesis, β-pinosomes begin to be formed at the periphery of the oocyte; these take in glycogen particles from the outside which are progressively broken into smaller units.     

STUDIES ON THE STRUCTURE OF MUSCLE : III. PHASE CONTRAST AND ELECTRON MICROSCOPY OF DIPTERAN FLIGHT MUSCLE

1. The flight muscles of blowflies are easily dispersed in appropriate media to form suspensions of myofibrils which are highly suitable for phase contrast observation of the band changes associated with ATP-induced contraction. 2. Fresh myofibrils show a simple band pattern in which the A substance is uniformly distributed throughout the sarcomere, while the pattern characteristic of glycerinated material is identical with that generally regarded as typical of relaxed vertebrate myofibrils (A, I, H, Z, and M bands present). 3. Unrestrained myofibrils of both fresh and glycerinated muscle shorten by not more than about 20 per cent on exposure to ATP. In both cases the A substance migrates during contraction and accumulates in dense bands in the Z region, while material also accumulates in the M region. It is proposed that these dense contraction bands be designated the C_z, and C_m bands respectively. In restrained myofibrils, the I band does not disappear, but the C_z and C_m bands still appear in the presence of ATP. 4. The birefringence of the myofibrils decreases somewhat during contraction, but the shift of A substance does not result in an increase of birefringence in the C_z and C_m bands. It seems therefore that the A substance, if it is oriented parallel with the fibre axis in the relaxed myofibril, must exist in a coiled or folded configuration in the C hands of contracted myofibrils. 5. The fine structure of the flight muscle has been determined from electron microscopic examination of ultrathin sections. The myofibrils are of roughly hexagonal cross-section and consist of a regular single hexagonal array of compound myofilaments the cores of which extend continuously throughout all bands of the sarcomere in all states of contraction or relaxation so far investigated. 6. Each myofilament is joined laterally with its six nearest neighbours by thin filamentous bridges which repeat at regular intervals along the fibre axis and are present in the A, I, and Z, but not in the H or M bands. When stained with PTA, the myofilaments display a compound structure. In the A band, a lightly staining medullary region about 40 A in diameter is surrounded by a densely staining cortex, the over-all diameter of the myofilament being about 120 A. This thick cortex is absent in the I and H bands, but a thinner cortex is often visible. 7. It is suggested that the basic structure is a longitudinally continuous framework of F actin filaments, which are linked periodically by the lateral bridges (possibly tropomyosin). The A substance is free under certain conditions to migrate to the Z bands to form the C_z bands. The material forming the C_m bands possibly represents another component of the A substance. The results do not clearly indicate whether myosin is confined to the A bands or distributed throughout the sarcomere.     

ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE : II. The Giant Ameba Pelomyxa carolinensis

Dividing nuclei from the giant ameba Pelomyxa carolinensis were fixed in osmium tetroxide solutions buffered with veronal acetate to pH 8.0. If divalent cations (0.002 M calcium, magnesium, or strontium as chlorides) were added to the fixation solution, fibrils that are 14 mµ in diameter and have a dense cortex are observed in the spindle. If the divalent ions were omitted, oriented particles of smaller size are present and fibrils are not obvious. The stages of mitosis were observed and spindle components compared. Fibrils fixed in the presence of calcium ions are not so well defined in early metaphase as later, but otherwise have the same diameter in the late metaphase, anaphase, and early telophase. Fibrils are surrounded by clouds of fine material except in early telophase, when they are formed into tight bundles lying in the cytoplasm unattached to nuclei. Metaphase and anaphase fibrils fixed without calcium ions are less well defined and are not observably different from each other. The observations are consistent with the concept that spindle fibrils are composed of polymerized, oriented protein molecules that are in equilibrium with and bathed in non-oriented molecules of the same protein. Partially formed spindle fibrils and ribosome-like particles were observed in the mixoplasm when the nuclear envelope had only small discontinuities. Remnants of the envelope are visible throughout division and are probably incorporated into the new envelope in the telophase. Ribosome-like particles are numerous in the metaphase and anaphase spindle but are not seen in the telophase nucleus, once the envelope is reestablished, or in the interphase nucleus.     

革蜱未成熟期哈氏器的扫描电镜研究

用扫描电镜观察了革蜱属8种幼虫和若虫的哈氏器,并与其他属5种幼虫和4种若虫的哈氏器进行比较,以阐明其形态特征及其在分类中的意义。其中,9种幼虫和8种若虫哈氏器的结构是首次报道。革蜱属幼期哈氏器的囊孔形状、前窝感毛数目及其中孔毛的位置等与其他属不同。东洋区的金泽革蜱与古北区的革蜱种类之间,在孔毛形状、位置和幼虫近端缝孔的位置上有明显差别。而后者中,阿坝革蜱幼虫一般无近端缝孔;网纹革蜱幼虫和若虫的囊孔形状和幼虫的近端缝孔的位置与其他种类不同。但其余几种革蜱幼虫和若虫的哈氏器无显著差别。     

革蜱成虫哈氏器的扫描电镜观察

本文报道了用扫描电镜观察革蜱属8种成虫的哈氏器.其中三种成虫(阿坝革蜱D. ahaensis、金泽革蜱D. auratus和中华革蜱D. sinicus)的哈氏器结构是首次报道,并与其他属6种成虫的哈氏器进行了比较,以阐明其形态特征及其在分类中的意义.另外,还将这14种成虫哈氏器与各自未成熟期的哈氏器进行了比较.分析和讨论了同种不同时期哈氏器结构的异同.东洋区的金泽革蜱和古北区的革蜱种类间,在孔毛形状,位置及基盘数目上有明显差别,而后者中,边缘革蜱D. marginatus的孔毛位于近端外侧,草原革蜱D. nuttalli和网纹革蜱D. reticulatus的孔毛位于远瑞外侧,其余种类无明显差别.     

中华蜜蜂工蜂触角感受器的扫描电镜观察

对中华蜜蜂(Apis cerana)工蜂触角感受器的扫描电镜观察,见到在触角上有九种类型的感受器,它们是板形感器、腔锥感器、坛形感器、钟形感器、锥形感器、毛形感器A、毛形感器B、毛形感器C和D、缘感器以及各种类型的刚毛等.对于这些感受器的外部形态和分布部位进行了详细地观察和描述,发现中华蜜蜂与西方意蜂(Apis mellifera)有差异.     

ELECTRON MICROSCOPIC STUDIES ON THE OOGENESIS OF DRAGONFLY AND CRICKET WITH SPECIAL REFERENCE TO THE PANOISTIC OVARIES

The successive ultrastructural changes during oogenesis in Sympetrum frequens (Odonata, Libellulidae) and Gryllus yemma (Orthoptera, Gryllidae) were studied.
The structures of the terminal filament and boundary between the terminal filament and the germarium differed from each other in these 2 species; in Sympetrum the boundary between the terminal filament and the germarium was a special acellular transverse septum, whereas that in Gryllus was composed of several flattened cells which seemed to be similar to the prefollicular cells in the germarium.
During the previtellogenesis, the nucleolar extrusions and emissions of the outer nuclear envelope were observed frequently in young oocytes. In Sympetrum , electron dense masses were observed in the oocyte cytoplasm, which seemed to be "yolk nuclei" or "Balbiani bodies" and were composed of aggregated small particles (about 200 A in diameter). They were gradually dispersed in the cytoplasm until the onset of vitellogenesis.
In both Sympetrum and Gryllus , yolk precursors seemed to be incorporated into oocytes by micropinocytosis as observed in various animals.
The egg membranes, viz. , the vitelline membrane and the chorion, seemed to be formed by products from follicle cells which developed rough-surfaced endoplasmic reticulum and Golgi bodies. Thus, both of these egg membranes were assumed to be the secondary egg membranes.     

小地老虎飞行肌的超微结构与飞行能力的研究

电镜观察的结果表明,小地老虎Agrotis ypsilon Rottem。的飞行肌具有十分发达的肌原纤维与线粒体;肌原纤维的收缩率较小,说明肌纤维对翅的高频振荡有很强的适应能力;在吊飞状态下,翅振频率高达100—120赫兹,飞速为7,500米/小时,一次能持续飞行10多小时。飞行时的呼吸率较静息时增加100倍左右,胸温升高5—9℃,每小时消耗脂肪5毫克。起飞的临界温度为8℃,其飞速随温度升高而提高。     

沙冬青根瘤菌的电子显微镜研究

用透射电镜研究沙冬青根瘤中的根瘤菌。这种根瘤菌的精细结构不仅与生态环境有关,而且还随寄主细胞发育程度不同而异。在早期侵染细胞中,根瘤菌很少,一般呈圆形或椭圆形,电子密度很高,位于细胞壁附近。在成熟侵染细胞中,根瘤菌很多,布满了整个细胞,形态出现多样化。在衰老侵染细胞中,根瘤菌形状不规则,细胞质收缩,电子密度增高,内部结构模糊不清,有的甚至变成一团膜泡状结构     

莫桑比克非鲫卵黄形成的电镜观察

运用透射电镜观察了莫桑比克非鲫卵母细胞的生长.根据卵母细胞的大小和内部结构特征,将其分为四个时期:卵母细胞生长早期:卵黄泡形成期:卵黄积累期:卵黄积累完成期.本文着重研究了主要卵黄成分--卵黄球的形成过程.卵黄球属外源性卵黄,由卵母细胞通过微胞饮作用吸收肝脏合成的卵黄蛋白原后形成的.在卵黄大量积累前,卵母细胞内的线粒体和多泡体聚集成团,构成卵黄核,继而线粒体大量增殖,线粒体形状发生改变,形成同心多层膜结构,为大量的卵黄物质积累提供场所.最终形成的卵黄球由被膜、卵黄结晶体和两者之间的非结晶区三部分组成.       

ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE : I. Amoeba proteus

Individual organisms of Amoeba proteus have been fixed in buffered osmium tetroxide in either 0.9 per cent NaCl or 0.01 per cent CaCl₂, sectioned, and studied in the electron microscope in interphase and in several stages of mitosis. The helices typical of interphase nuclei do not coexist with condensed chromatin and thus either represent a DNA configuration unique to interphase or are not DNA at all. The membranes of the complex nuclear envelope are present in all stages observed but are discontinuous in metaphase. The inner, thick, honeycomb layer of the nuclear envelope disappears during prophase, reappearing after telophase when nuclear reconstruction is in progress. Nucleoli decrease in size and number during prophase and re-form during telophase in association with the chromatin network. In the early reconstruction nucleus, the nucleolar material forms into thin, sheet-like configurations which are closely associated with small amounts of chromatin and are closely applied to the inner, partially formed layer of the nuclear envelope. It is proposed that nucleolar material is implicated in the formation of the inner layer of the envelope and that there is a configuration of nucleolar material peculiar to this time. The plasmalemma is partially denuded of its fringe-like material during division.     

ULTRASTRUCTURE OF THE DINOFLAGELLATE PERIDINIUM CINCTUM F. OVOPLANUM. II. LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS ON FERTILIZATION

Fertilization in Peridinium cinctum f. ovoplamtm has been investigated at both the light and electron microscopic levels. Gamete formation occurs when vegetative cells are placed into nitrogen deficient media. The majority of gametes observed possess thin thecal plates; however, some are naked. Gametes have few chloroplasts as compared to vegetative cells, numerous membrane bounded storage bodies, many starch grains, and chromosomes which appear slightly unwound. Gamete fusion is observed to peak 7–10 days after inoculation into nitrogen deficient media. Fusion occurs in an area of the sulcus devoid of reticulate thecal plates at or adjacent to the flagellar pores. A fertilization tube is formed and proceeds to widen along the sulcus. Karyogamy occurs within the fertilization tube before plasmogamy is completed. The resulting planozygote is a two walled structure containing two longitudinal flagella. It enlarges over a 2-week period giving rise to the hypnozygote.