Scanning electron microscope study of epidermal surface of six ectosymbiotic Temnocephala species (Platyhelminthes) from Argentina

The epidermis of six ectosymbiontic Temnocephala species (T. axenos, T. chilensis, T. digitata, T. microdactyla and T. pignalberiae from freshwater crustaceans and T. iheringi from a mollusc) from Argentina examined using scanning electron microscopy revealed characters indicating their relationships with other members of the Platyhelminthes and with the congeneric Australian and New Zealand species. In all species, the whole surface is covered with microvilli and no locomotory cilia were observed. Aggregates of monociliated receptors are on the tentacles of all species and on the ventral surfaces of three. Furthermore, T. axenos and T. chilensis show other ciliated structures interpreted as collar receptors, such as those described for some turbellarian groups (e.g. Proseriata and Rhabdocoela). Two species (T. digitata and T. iheringi) show structures that are probably related to the duo-gland adhesive system.     

A parvo-like virus in cultured redclaw crayfish Cherax quadricarinatus from Queensland,Australia

In the summer of 1999/2000, an epizootic occurred in cultured juvenile redclaw crayfish Cherax quadricarinatus on one commercial crayfish farm in northern Queensland, Australia. Mortalities occurred over 4 wk, with up to 96% cumulative mortalities in 2 earthen ponds stocked with juveniles. The crayfish were weak, anorexic and lethargic. A transmission trial was conducted, using filtered, cell-free extract prepared from infected crayfish as inoculum. The disease was reproduced, with on-going mortalities occurring in inoculated crayfish over 55 d. Experimentally inoculated crayfish showed gross signs of malaise, anorexia and disorientation before dying. Two types of intranuclear inclusion bodies (INIBs) were seen in tissues of endodermal, ectodermal and mesodermal origin by light microscopy with haematoxylin and eosin (H&E) stained sections. 'Early'-stage INIBs were eosinophilic, rounded and located centrally within slightly enlarged nuclei while 'late'-stage INIBs were well-rounded and deeply basophilic. The gills, cuticular epithelium and epithelial cells of the foregut, midgut and hindgut were the most heavily infected tissues. By transmission electron microscopy, virions with an average diameter of 19.5 nm were seen within electron-dense granular inclusion bodies within enlarged nuclei of both naturally and experimentally infected crayfish. The size of the virions and cytopathology are consistent with characteristics of viruses in the Family Parvoviridae. This is the first reported case of mass mortality caused by a parvo-like virus infection in C. quadricarinatus.     

Temnocephalan symbionts of the freshwater crayfish Cherax quadricarinatus from northern Australia

Four species of turbellarian temnocephalan symbionts (Platyhelminthes: Temnocephalida) are reported for the first time from the external surfaces of Cherax quadricarinatus, a freshwater crayfish from northern Australia. Three of these species — Temnocephala rouxii Merton, 1913, Notodactylus handschini (Baer, 1945), and Diceratocephala boschmai Baer, 1953 — are known previously from related crayfish in New Guinea. The newly discovered fourth species, Decadidymus gulosus n. gen., n. sp., has an unusual combination of characters linking it with both the Temnocephalidae and the Scutariellidae. Together the four species possess an array of characters that challenges current concepts of families in the order. D. boschmai has an almost completely ciliated epidermis, a feature otherwise unknown in the order.     

Cosmos pollen ontogeny: A scanning electron microscope study

Summary Ontogenetic data concerning pollen not only clarifies the mode of deposition of the elaborate walls but has considerable functional and taxonomic relevance. Hitherto such studies have used optical or transmission electron microscopy but here a recently devised preparative technique has enabled pollen development inCosmos bipinnatus to be studied using the scanning electron microscope. The technique involves freeze-fracturing of osmium fixed, cryoprotected anthers, maceration in dilute osmium tetroxide, critical point drying, sputter coating and examination. The processes of pollen wall development can then be observed in three dimensions, an important aid to understanding the spatial relationships involved in the determination of ornamentation and apertures. Details of the pollen and tapetum are described at various stages between meiosis and anthesis. A close conformity is demonstrated between the results obtained and those of earlier transmission electron microscopic studies of the same and related species although very different interpretations are made.     

The life history and biology of Diceratocephala boschmai (Platyhelminthes; Temnocephalida), an ectosymbiont on the redclaw crayfish Cherax quadricarinatus

Adults of the temnocephalan Diceratocephala boschmai, an ectocommensal on the crayfish Cherax quadricarinatus, deposited eggs on the host carapace. After 15 to 20 days at 28 °C, the eggs hatched into ciliated miniature adults with undeveloped reproductive organs, that remained attached to the host alongside the eggs. They grew and became gravid within 53 to 70 days if they were not dislodged. Most oviposited on the host on which they had hatched. Although larval temnocephalans have been described from in vitro work, this is the first temnocephalan life history to be described in vivo.Juvenile worms frequently changed their position on the carapace. Adult worms were sedentary just prior to, and during oviposition, and were frequently found at the base of the large chelae, the ventral surface of the antennae and antennules, and at the base of the walking legs. The ventral margins of the abdomen, the mouthparts, and the interorbital-rostral area were secondarily inhabited.It was calculated using an indirect regression that adult Diceratocephala boschmai survived on average 91 days when removed from the host but they did not produce eggs in vitro. On the host, adult worms lived an average of 48 days after the commencement of oviposition.Abbreviations C cilia - E eyespot - Es ejaculatory sac - Ex excretory canal - G gut - Gl glands - I intertentacular flange - M muscular peduncle - O ovary - P penis - Pg pharyngeal glands - Ph pharynx - R rhabdites - S seminal vesicle - T tentacles - Te testes - U uterus - Vd vas deferens - Vit vitelline glands     

The ultrastructure of the lens of the cephalopod Sepiola: A scanning electron microscopic study

The ultrastructure of the eye lens of Sepiola atlantica was investigated using scanning electron microscopy. The main lens elements in both the anterior and posterior half of the Sepiola lens are plate-like configurations with fiber-like extensions at their margins. Anteriorly the plates are plano-convex, posteriorly subspherical. The central, primordial, posterior plates are spherical with no marginal extensions. The plates are mutually anchored by protrusions and invaginations and by push-button attachments. The posterior and anterior halves are separated by a septum which consists of concentric zones of radially orientated elongated cells. The marginal extensions of the plates and the septal elements are closely associated. The unique structure of the septum makes it a good candidate for the high resistance barrier between the posterior and anterior halves of the Sepiola lens (Jacob and Duncan, 1981).     

Observation of Protoplasts from the Conidia of Arthrinium Aureum by scanning electron microscopy

Protoplast formation from conidia of Arthrinium aureum was achieved with Lysing Enzyme L-2265 (Sigma Chemical) from Trichoderma harzianum. Scanning electron microscopy of conidia protoplasts showed the acquired spherical shape.     

Antifungal activity of allylamines on Epidermophyton floccosum: scanning electron microscopy study

The action of allylamine antifungal agents on Epidermophyton floccosum was studied using scanning electron microscopy. After 7 days of culture on Sabouraud dextrose agar, Epidermophyton floccosum samples were brought in contact with concentrations of 0.2 and 2 g ml^–1 and 0.01 and 0.1 g ml^–1 of naftifine and terbinafine, respectively. Lesions observed after 24 h, 3 and 7 days of contact were mainly on the structure and rigidity of the mycelial and macroconidial wall. They were characterized by hyphal ballooning and twisting and by apical bulbous bulges. Deterioration of macroconidia was characterized by wall exfoliation. The intensity of the deterioration depended on the dose and only slightly on the length of time that the sample and the antifungal drug were in contact.     

Renal microvasculature in the adult pipid frog,Xenopus laevis: A scanning electron microscope study of vascular corrosion casts

We studied the opisthonephric (mesonephric) kidneys of adult male and female Xenopus laevis using scanning electron microscopy (SEM) of vascular corrosion casts and light microscopy of paraplast embedded tissue sections. Both techniques displayed glomeruli from ventral to mid-dorsal regions of the kidneys with single glomeruli located dorsally close beneath the renal capsule. Glomeruli in general were fed by a single afferent arteriole and drained via a single thinner efferent arteriole into peritubular vessels. Light microscopy and SEM of vascular corrosion casts revealed sphincters at the origins of afferent arterioles, which arose closely, spaced from their parent renal arteries. The second source of renal blood supply via renal portal veins varied interindividually in branching patterns with vessels showing up to five branching orders before they became peritubular vessels. Main trunks and their first- and second-order branches revealed clear longish endothelial cell nuclei imprint patterns oriented parallel to the vessels longitudinal axis, a pattern characteristic for arteries. Peritubular vessels had irregular contours and were never seen as clear cylindrical structures. They ran rather parallel, anastomosed with neighbors and changed into renal venules and veins, which finally emptied into the ventrally located posterior caval vein. A third source of blood supply of the peritubular vessels by straight terminal portions of renal arteries (vasa recta) was not found.     

沙蒿大粒象触角感器的扫描电镜观察

应用扫描电镜技术,对沙蒿大粒象Adosomus sp.触角感器的类型、分布、数量以及雌雄之间的差异进行了详细研究。结果表明:沙蒿大粒象触角上共有5种感器类型,包括板形感器(Ⅰ、Ⅱ和Ⅲ型)、毛形感器和刺形感器。触角各节的感器类型和分布差异较大,以板形感器的分布最广、数量最多,在触角各节均有分布;刺形感器分布在索节第1亚节和棒节,而毛形感器仅分布在棒节且数量较少。雌雄触角的感器类型及分布基本一致,但分布数量上雄虫明显多于雌虫。     

The digestive tract of the amberjack Seriola dumerili, Risso: a light and scanning electron microscope study

The histology of the digestive tract of the amberjack ( Seriola dumerili , Risso) was studied using light and scanning electron microscopy. The anterior oesophagus mucosa displays primary and secondary folds lined with a stratified squamous epithelium with fingerprint-like microridges which is substituted, on the top of the oesogaster folds, by a simple columnar epithelium with short microvilli. Only primary folds are present in the stomach. The anterior portion is rich in simple tubular glands, whereas the oesogaster and the pyloric region are devoid of them. Pyloric caeca and anterior and middle intestine mucosa display the same pattern of folding. The dominant cell type is the enterocyte, which exhibits larger and thinner microvilli in the caeca than in the intestine. The columnar epithelium of the rectum is replaced, in the anal sphincter, by a stratified flattened epithelium. Goblet cells are numerous throughout the whole length of the tract with the exception of the initial part of the oesophagus, the oesogaster, the stomach and the anal sphincter. Mucosubstances have been shown to vary in the different regions of the gut: acid mucines are found in the oesophagus, pyloric stomach, caeca, intestine and rectum, whereas neutral mucosubstances dominate in the anterior portion of the stomach. The muscularis is well developed throughout the length of the tract: two layers of striated muscle at the oesophageal level; two layers of smooth muscle in the stomach wall and three at the intestinal level.     

Effects of Diazinon on bluegill sunfish, Lepomis macrochirus, gills: scanning electron microscope observations

Gills of bluegill sunfish, Lepomis macrochirus, exhibited varied degrees of structural damage following a 24-h exposure to sublethal concentrations (15 μg/l, 30 μg/l, 45 μg/l, 60 μg/l and 75 μg/l) of Diazinon [O,O-diethyl-O-(2-isopropyl-6-methyl-4 pyrimidinyl ester or phosphorothioate]. Exposure to 15 μg/l and 30 μg/l resulted in exocytosis of some material to the cell surface and perforations of the microridges. At higher doses (above 45 μg/l), the extrusion was reduced and the cells were swollen. Compared to control values, the thickness of the microridge on the gill arch and on the gill filament generally increased with exposure to Diazinon. Also, the distance between microridges decreased with increased exposure concentrations. At 60 μg/l, gill arch microridges fused and some ridges of gill filaments disappeared. At 75 μg/l exposure, epithelial cells of the gill arch became obscured with severe cellular extrusions and the lamellar surfaces swelled. The mucus extrusion, lamellar swelling and reduced microridges may be related to a defence mechanism which reduces the water surface around the gill and increases the barrier distance for diffusion of toxicants from outside to the blood capillaries. Although this mechanism protects the fish from toxicants, it also reduces the oxygen supply which leads to suffocation of the fish.     

Observation of Woronin bodies in Arthrinium aureum by scanning electron microscopy

Woronin bodies are cytoplasmic organelles of filamentous fungi that can be observed on one, or both sides of each septum. The goal of this paper is to illustrate the presence of them in hyphae of Arthrinium aureum by means of scanning electron microscopy and to show that they act as a safety plug to close septa pores in hypha. Results show that Woronin bodies as an immediate response to prevent a cytoplasm loss. Results support hypothesis proposed previously in literature. This revised version was published online in June 2006 with corrections to the Cover Date.     

A simple freeze dehydration method for studying epiphytic and epizoic communities using the scanning electron microscope

Freeze dehydration provides instant immobilisation and fixation of living materials to capture particular events and avoids the need for dehydration through an ethanol series for SEM viewing. Examples of the technique are given from freshwater epiphytic and epizoic communities. The species and community architectures found show the great need which exists for the study of the biology of these systems in their natural, undisrupted states.     

Comparative scanning electron microscope (SEM) study of miracidia of four human schistosome species

The miracidia of four human blood flukes, Schistosoma haematobium, S. intercalatum, S. mansoni and S. japonicum, have been studied by means of the scanning electron microscope (SEM). Differences have been observed in their respective dimensions, in the configuration of their terebratoria (apical papillae), in the shape of the epidermal plates, and in the distribution of the sensory receptors. The most evident differences have been noticed on the terebratoria where two main patterns of organization of the anastomosing membrane foldings have been described: (1) a ‘rosette’ pattern observed in S. haematobium and S. intercalatum and (2) a ‘honeycomb’ pattern in S. mansoni and S. japonicum. The structure and the taxonomic importance of these morphological features are analysed.     

A scanning electron microscope study of the papilla basilaris of Gekko gecko

Summary The sensory hair cells of the ventral 2/3 of the papilla basilaris of Gekko gecko are divided into anterior (pre-axial) and posterior (post-axial) portions by a mid-axial gap or hiatus where there are no hair cells. There is no separation of the hair cells in the dorsal third of the papilla. There are three tectorial membrane modifications: an attached thickened membrane covering the pre-axial hair cells, sallets covering the post-axial hair cells, and an attached filamentous membrane covering the dorsal hair cells. The number of hair cells is greatest ventrally and decreases dorsally. There are approximately 2000 to 2100 hair cells. The kinocilia of the hair cells of the anterior halves of both the pre- and the post-axial vertical hair-cell rows are oriented posteriorly, while the kinocilia of the posterior halves are oriented anteriorly. The kinocilia of the hair cells of the dorsal third of the papilla are mostly oriented posteriorly. Thus, kinocilial orientation of the ventral 2/3 of the papilla is doubly bidirectional, and the dorsal 1/3, largely unidirectional.I would like to thank Ms. Maria Maglio for her skill in handling the technical aspects of the scanning electron microscopy as well as her artistry in achieving photographic excellence on the scope, David Akers for expert photographic assistance, and Wayne Emery for the drawings. Research sponsored by United States Public Health Service Grant NS-09231.     

Comparative studies on scanning electron microscopy of trophi of the genus Filinia Bory De St. Vincent (Rotifera)

Trophi of Filinia species from 16 South Island lakes and three North Island lakes of New Zealand were examined and compared with specimens from Australia, Austria, Belgium, and Turkey. Five species of Filinia (brachiata, longiseta, cf. pejleri, novaezealandiae, and terminalis) were positively identified from the New Zealand samples. Numbers of unci teeth are considered to be the most reliable features for identification within the genus. Numbers obtained from SEM for other species of Filinia (australiensis, grandis, and hofmanni) are also listed for the first time.     

On the presence of the Australian redclaw crayfish, <Emphasis Type="Italic">Cherax quadricarinatus</Emphasis>, in Mexico

The first reports of wild caught Australian redclaw crayfish from Mexico, in the states of Morelos and Tamaulipas, are presented. Redclaw crayfish were first brought to Mexico in 1995 to initiate experimental cultures at several research centers. In the following years a number of private ventures started commercial cultures, several of which in the states of Morelos and Tamaulipas are thought to have been the sources for the wild populations recorded in this study. The farms that acted as the original sources have not been operating for at least 2 years. In Morelos, high densities and all size classes of redclaws, including ovigerous females, were captured in natural waterways; whereas in Tamaulipas they were found at four sites occurring in irrigation canals in an agricultural district. The size attained by the wild redclaws, the abiotic conditions in which they were found and the potential for spread within the drainage systems of the Balsas and Tamesi Rivers are discussed.     

The sub-membrane reticulum of the human erythrocyte: A scanning electron microscope study

A web-like reticulum underlying the human erythrocyte membrane was studied at a resolution of 5–10 nm by means of a scanning electron microscope. The network was visualized in isolated membranes (ghosts) torn open to reveal their interior space and in residues derived from ghosts extracted with Triton X-100. It formed a continuous (rather than patchy) cover over the entire cytoplasmic surface, except where lifted off or torn away. Filaments (5–40 nm in diameter), annular figures (40–60 nm in diameter), and nodes (30–100 nm in diameter) were prominent in different networks. The dimensions of the filaments and the interstices in the reticulum varied with conditions, suggesting that the network has elastic properties. This reticulum is probably related to the erythrocyte membrane proteins spectrin and actin.