Sensilla on the aedeagus of the ground beetle Carabus (Ohomopterus) arrowianus arrowianus (Breuning) (Coleoptera: Carabidae)

Sensilla on the aedeagus of the ground beetle Carabus (Ohomopterus) arrowianus arrowianus (Breuning) were investigated by scanning electron microscopy. On the aedeagus, a total of six types of sensillum were confirmed: five basiconic and one coeloconic. The external features and distributional patterns of the sensilla are described.     

A STRUCTURAL AND FUNCTIONAL STUDY OF THE COORDINATED REACTIONS OF INDIVIDUAL COMMELINA COMMUNIS L. STOMATA (COMMELINACEAE)

Opening and closure movements of individual stomata were analyzed by light microscopy, scanning electron microscopy, and time-lapse photomicrography. Turgor-pressure-induced changes in pore shape of Commelina communis L. stomata were observed in vivo and in fixed material. The ventral wall of the guard cells undergoes three-dimensional alterations during opening and closing. Stomatal aperture increases with increase in light intensity and with decrease in CO₂ concentration as previously described, while reactions to relative humidity and anaerobiosis are somewhat divergent from common experience. Low humidity induces opening rather than closure of stomata in well watered greenhouse plants, and lack of oxygen induces consecutive opening and closure movements. Individual stomata characteristically open by three distinct steps: (1) rapid opening; (2) immobility or slow closure; (3) relatively rapid opening. Since the timing of the second step varies for individual stomata, it is obscured by methods that integrate the responses of several stomata. The movements of individual stomata are well synchronized, but active communication between stomata in different areas can not be confirmed.     

ULTRASTRUCTURE OF PRYMNESIUM NEMAMETHECUM SP. NOV. (PRYMNESIOPHYCEAE)1

Based on material collected from Cape Town, a new sand-dwelling, marine species of Prymnesium is described. Using light and electron microscopy, Prymnesium nemamethecum sp. nov. has been found to resemble other species of the genus in size, organelle arrangement, and swimming behavior. It differs from other described species in that it has three types of scales, one of which is confined to the region of appendage insertion and forms a sheath of simple plate scales over the haptonema. In addition, the scales constituting the proximal body scale layer(s) are unusual because they are not simple plate scales but are specifically ornamented.     

Cymbella Agardh属(硅藻门Bacillariophyta)的一个新化石种的发现及其微细构造

新化石种Cymbella taicuonensis Li et Zheng sp.nov.是在研究西藏西北部日土县台错古湖剖面沉积物中硅藻植物群时发现的,剖面沉积物中保存了非常丰富的硅藻化石,Cymbella taicuonensis就是这些硅藻化石中的一个新化石种。对标本采用光学镜(LM)和扫描电镜(SEM)观察和照相,并对其微细构造进行深入的研究。     

ORGANIZATION OF ISOLATED EMBRYO SACS AND EGGS OF PLUMBAGO ZEYLANICA (PLUMBAGINACEAE) BEFORE AND AFTER FERTILIZATION

The organization of isolated embryo sacs and eggs of Plumbago zeylanica was described before and after fertilization using microscopic cytochemistry and scanning electron microscopy. Major developmental events of fertilization, including preferential fertilization and early embryogenesis, are described in isolated embryo sacs. The two sperms, one unassociated with vegetative nucleus (S_ua) and the other physically associated with the vegetative nucleus (S_vn), fuse with nuclei of egg and central cell, respectively. The zygote divides asymmetrically to form a two-celled embryo, consisting of a massive suspensor occupying most of the micropylar portion of the embryo during early embryogenesis. Plastids are distributed in the perinuclear and micropylar regions of the egg cell and in cytoplasmic strands of the central cell before fertilization. Calcofluor white-positive fibrillar material in the filiform apparatus (presumed β-1,4 linked glucans) was investigated using scanning electron microscopy. The egg of P. zeylanica can easily be divided into three cytologically distinct regions: 1) perinuclear cytoplasm, 2) lateral cytoplasm, and 3) micropylar cytoplasm. Cytological differences are evident in the organization of the cell walls, general degree of vacuolization, and the distribution of heritable organelles, storage bodies, and microtubules. The present study supports the concept that the egg of P. zeylanica plays combined synergid and gamete functions.     

Description of the glochidium of Margaritifera auricularia (Spengler 1793) (Bivalvia,Unionoidea)

The glochidium of Margaritifera auricularia is described for the first time by using light microscopy, scanning electron microscopy and histological techniques. The larval mantle is formed by only two layers of cells; the inner one being much thicker, with microvilli. All cell masses of the glochidium are temporary aggregations that are the rudiments of organs of the subsequent juveniles which will be released after metamorphosis in the host tissues. In the glochidium there are three main masses of cells: (i) the muscle, which is in an anterior position; (ii) the oral plate in the centre of the larva; and (iii) the more ventrally and posteriorly situated ventral plate, or foot rudiment, flanged with lateral pits all bearing dense cilia. No rudimentary organs such as the pericardium, the kidney, the heart or nerve ganglia have developed. There are no visible hooks in the valve margins, but by using light microscopy we observed minute teeth covered by a rim of the periostracum. Near the margin of the shell there are two pairs of sensory hair tufts only observable by scanning electron microscopy. The glochidium of M. auricularia is the largest of the family Margaritiferidae and intermediate between the glochidium of the known species of this family and those of Unionidae.     

螽斯前肠的内部形态及其分类学价值的研究(螽斯总科,拟叶螽科,螽斯科)

前肠作为昆虫的暂时储存并初步消化食物的场所,不同的种类在内部结构上有所不同,并已证明其作为分类特征的可靠性.运用生理解剖及扫描电镜技术对螽斯总科拟叶螽科Pseudophyllidae 2属3种和螽斯科Tettigoniidae 2属3种螽斯的前肠几丁质内壁结构进行比较分析.研究表明,前肠的内部形态,属间差异明显,可以作为形态分类的一个有用特征.此外还对螽斯前肠的内壁结构同食性关系进行了初步探讨.     

成年草鱼外周血细胞的超微结构

用透视电镜技术研究了成年草鱼外周血细胞的超微结构，结果表明：在外周血细胞中可区分出红细胞，淋巴细胞，单核细胞，嗜中性白细胞，嗜酸性白细胞和血检细胞；嗜碱性白细胞无论在血涂片上或超薄切片上都没有发现。电镜图像显示，在红细胞中，仅能看到少数线粒体和液泡。淋巴细胞以短的伪足，较多的游离核糖体和滑面内质网为其特征。单核细胞的特征是具有较多的伪足和胞质液泡以及偏位核。在外周血液中发现了嗜中性白细胞生长、发育、功能成熟和衰退的全过程，描述了嗜中性白细胞的幼稚型、成熟型和衰退型细胞的超微结构。在成年草鱼外周血中，还发现了一种新型的颗粒细胞，它的特殊颗粒为大的六角形或棒状致密结晶颗粒，对上述特殊颗粒细胞的属性也进行了讨论。     

Mallomonadaceae (Chrysophyceae) from Malaysia and Australia

The Mallomonadaceae (Chrysophyceae) of Malaysia and Australia are described by scanning and transmission electron microscopy. Thirty taxa are reported from Malaysia, twenty eight for the first time. Eighteen taxa are reported from Australia, twelve for the first time. Twelve taxa are reported for the first time from the tropics. Four new taxa, Mallomonas ocellata sp. nov., M. tropica sp. nov., M. favosa f. gemina f. nov. and Chrysosphaerella astrea sp. nov. are described and the diagnosis of Mallomonas adamas Harris et Bradley is emended.     

OBSERVATIONS OF A TUBE-DWELLING DIATOM: NAVICULA HAMULIFERA (BACILLARIOPHYCEAE)1

Colonies of the tube-dwelling diatom Navicula hamulifera Grunow living on mangrove prop roots in Indian River, Florida and at La Parguera, Puerto Rico, were studied using light and electron microscopy. Observations of the tube morphology and cell structure of this diatom from fresh samples and cultures are described, as well as the ultrastructural morphology of its frustule. The formation of tubes by this diatom is reported for the first time. Comparisons are made with the closest species; Navicula delognei V.H. and Navicula pseudoco moides Hendey.     

CALCIUM PHOSPHATE GRANULES IN THE REPRODUCTIVE SYSTEM OF OXYCHILUS ATLANTICUS (GASTROPODA: PULMONATA)

The presence of connective interstitial cells in the wall ofseveral organs of the distal reproductive system in Oxychilus atlanticusis described by means of scanning electron microscopy (SEM).Connective interstitial cells extend from the distal part of thevas deferens to the penis, being the dominant cell type of large portionsof the epiphallus as well as in the whole penial caecum (=flagellum).These cells are highly mineralized and are characterized bythe presence of large amounts of solid spherules (up to 4 mmin diameter) in their cytoplasm. A semi-quantitative evaluationby X-ray microanalysis demonstrates that calcium and phosphorusare the main elements of the spherules. Their function is unknown,but they could aid in copulation or they could assist the survivalof the transferred spermatozoa. (Received 7 June 1999; accepted 8 September 1999)     

双菱藻科（硅藻门）——四个中国新纪录种

本文报道了采自新疆及云南地区的双菱藻科（硅藻门）中国新纪录植物4种,分别为耳蜗波缘藻Cymato—pleura cochlea Brun、维苏双菱藻Surirella visurgis Hustedt、盾状马鞍藻Campylodiscus clypeus Ehrenberg和莱温德马鞍藻Campylodiscus levanderi Hustedt。通过光镜（LM）和扫描电镜（SEM）观察,对其分类学特征进行了详细的描述,并介绍了他们的生境特征等。     

FINE STRUCTURE OF THE NEUROHYPOPHYSIS OF THE OPOSSUM (DIDELPHIS VIRGINIANA)

The neurohypophysis of the opossum (Didelphis virginiana) was studied by electron microscopy in order to amplify Bodian''s classic light microscopic observations in which he demonstrated a definite lobular pattern. The lobule of the opossum neurohypophysis is divided into three regions: a hilar, a palisade, and a septal zone. The hilar portion contains bundles of nerve fibers, the extensions of the hypothalamo-hypophyseal tract containing neurofilaments but few neurosecretory granules. In the opossum, pituicytes have a densely fibrillar cytoplasm. Herring bodies are prominent in the hilar region. They are large bodies packed with neurosecretory granules that have been described as end bulb formations of axons. From the hilar region, axons fan out into a palisade zone where the nerve terminals packed with neurosecretory granules, mitochondria, and microvesicles abut upon basement membranes. The neurosecretory granules are similar to those present in the neurohypophysis of other mammals, except for an occasional huge granule of distinctive type. Material morphologically and histochemically resembling glycogen occurs as scattered particles and as aggregates within nerve fibers. The septal zone, containing collagen, fibroblasts, and numerous small capillaries, is separated from the adjacent glandular tissue by a basement membrane.     

The spatial-temporal distribution of pico-sized (0.2–2.0 μm) detrital particles (Picodetritus) in the upper Volga reservoirs

The first data on the content of pico-sized detrital particles (0.2–2.0 μm) are obtained by epifluorescence microscopy in the upper Volga reservoirs. The spatial and temporal distributions of density and mass of picodetritus are described. The quantitative proportions between heterotrophic bacteria, picophytoplankton, and pico-sized detritus were revealed.     

POLYTENE CHROMOSOMES ISOLATED FROM NUCLEI OF TOKUNAGAYUSURIKA AKAMUSHI (DIPTERA, CHIRONOMIDAE): STRUCTURAL TRANSFORMATION CAUSED BY SALT, DETERGENT POLYANIONS AND ENZYMES

Polytene chromosomes of Tokunagayusurika akamushi (Chironomidae) were isolated from nuclei of the salivary glands. The isolated chromosomes retained their normal morphology, revealing bands by phase contrast microscopy.
Extensive structural transformations were observed when the isolated chromosomes were immersed in solutions of high salt concentration, polyanions (dextran sulfate and heparin), the ionic detergent SDS (0.01% or more) or enzymes. The morphological changes could be described in terms of combinations of the following characteristics: (1) reversible or irreversible changes, (2) expansion or no expansion, (3) disappearance of bands, and (4) appearance of new bands. The structural features of the transformed chromosomes are described.     

SOME ASPECTS OF MORPHOLOGICAL VARIATION IN STEPHANODISCUS NIAGARAE (BACILLARIOPHYCEAE)1

Valves of S. niagarae var. niagarae Ehr. and S. niagarae var. magnifica Fricke from geographically dispersed sediment and plankton collections were observed by light microscopy and scanning electron microscopy (LM and SEM). Measurements made by LM can be arranged so that means and ranges of diameter, areolar density, or strial density intergrade from one population into the next. Mean diameter is negatively related to increasing areolar and strial densities. No unique features observable by SEM distinguish the two described varieties. Thus, S. niagarae var. magnifica, having large diameter valves with low areolar and strial densities, may represent one end of a trend in overall variation in S. niagarae. At the opposite extreme are the populations with small valves and high areolar densities which are often erroneously referred to as S. astraea. Type material of S. niagarae lies intermediate to these forms. Three populations considered in this study have distinct morphological characteristics. Valves from Yellowstone Lake sediments have spine placements distinctly different from valves of all other populations. Specimens from Lake Superior have nearly flat central areas. Ribs of valves from Grand Traverse Bay (Lake Michigan) are covered with granules.     

THE MORPHOLOGY AND FINE STRUCTURE OF CERATIUM HIRUNDINELLA (DINOPHYCEAE)1

Some aspects of thecal morphology in Ceratium hirundinella are redescribed by means of scanning electron microscopy. The internal anatomy of the cell has been clearly revealed for the first time in serial sections examined by transmission electron microscopy. An unusual sulcus, termed the sulcul aperture, has been found to open into a large ventral chamber which extends toward the center of the cell. The 2 flagella are inserted at one side of the ventral chamber. The ultrastructure of the flagellar canals and root systems arc described in detail. A microtubular strand has been found to run from near the nucleus to near the flagellar bases but not to conned with either. The fine structure of the theca, trichocysts, nucleus, and chloroplasts is basically similar to that of other dinoflagellates. Food vacuoles are reported. These contain material thought to be undergoing digestion. It is suggested that the food particles enter the cell by way of the ventral chamber, which is lined only by membranes, unlike the rest of the cell, which is covered by thick plates. The new findings are discussed in relation to the earlier work on the species and to the fine structure of oilier dinoflagellates.     

OBSERVATIONS OF A TUBE-DWELLING DIATOM: NAVICULA HAMULIFERA (BACILLARIOPHYCEAE)1

Colonies of the tube-dwelling diatom Navicula hamulifera Grunow living on mangrove prop roots in Indian River. Florida and at La Parguera, Puerto Rico, were studied using light and electron microscopy. Observations of the tube morphology and cell structure of this diatom from fresh samples and cultures are described, as well as the ultrastructural morphology of its frustule. The formation of tubes by this diatom is reported for the first time. Comparisons are made with the closest species; Navicula delognei V.H. and Navicula pseudocomoides Hendey.