Intraspecific variation in spermoderm pattern of tribe Acacieae (Mimosoideae) using scanning electron microscopy techniques

Current research carried out in Pakistan is the first report on spermoderm ornamentation of eight species of tribe Acacieae (Mimosoidae) by using scanning electron microscopic techniques representing two genera, Fedherbia and Acacia were examined. Different spermoderm ornamentation were observed, described and discussed for their taxonomic importance. Seeds surfaces of the studied tribe possess novel variations in macro and micro morphology. Great variations were observed in both qualitative and quantitative characters of seeds. Seeds shape was oblong, ovate to elliptical and spermoderm ornamentation was levigate, rugose, polygonal and discoid, colliculate, and papillose type. These variations in the spermoderm ornamentation can be used as an aid in identification and classification of the members of tribe Acacieae.     

Macromorphological and micromorphological seed features of selected taxa of Caesalpiniaceae using light and scanning electron microscopy

Seed micromorphological and macromorphological characteristics of 12 taxa of Caesalpiniaceae from Pakistan have been studied, using light and scanning electron microscopy, to investigate the importance of seed coat features as a taxonomic tool. Great variations have been observed in color, shape, dimension, and seed surface pattern among the different genera of the family. A taxonomic key was prepared for the studied taxa. Six types of seed shapes were observed; circular, elliptical, irregular, oblong, oval, and ovoid. All examined seeds were hard except fragile seeds of Haematoxylom campechianum. Eight types of surface ornamentation have been noticed that include levigate, lugose, papillate, reticulate, reticulate irregular, reticulate regular, rhombus, and rogues. Majority of the taxa has been observed with thick ornamentation wall but thin ornamentation wall has also been recorded in few species. Fracture line of the various patterns was present in all taxa except genus Bauhinia. Three types of texture crudeness; coarse, medium, and fine have been recorded. Both micromorphological and macromorphological characters of seed are very fruitful in identification and classification of Caesalpiniaceae.     

Using microscopic techniques for taxonomic implications of seed and fruits of Delphinium L. (sensu lato) (Ranunculaceae)

In present research, micromorphological characters of the genus Delphinium L. (sensu lato) Ranunculaceae seeds and fruits were studied using microscopic techniques. A total of 37 species were studied using light (LM) and scanning electron microscopy (SEM) to evaluate seeds and fruits micromorphological characteristics for the taxonomic identification and species relationship in the genus. For each taxon, 33 characters were observed and studied. All characters were analyzed using MVSP software and UPGMA method by using dissimilarity index (average taxonomic distance). Considerable differences were observed in trichomes shape of fruit and seed color features. The results revealed that all studied taxa are separated into three clades. The first clade consists of D. pallidiflorum and D. semibarbatum, which have black seed and two types of glandular and crispate trichomes in fruit. The second clade consists of D. speciosum, D. szowitsianum, D. dasystachyson, D. aquilegifolium, D. ursinum, C. trigonelloides, and C. camptocarpa, which had a brown color seeds, two types of glandular and villous trichomes on fruits also have been observed. The remaining species were classified as third clade having various colors including yellow, black, and brown color seeds, the trichome shapes included one of the following forms strigose, villous, trichomes less, glandular, hooked, and crispate trichomes in fruits. The aim of the present study is to use micromorphological characters of seeds and fruits for the taxonomic identification and species delimitation in the genus Delphinium.     

Taxonomic significance of caryopsis in subfamily Panicoideae (Poaceae) using scanning electron microscopy and light microscopy

In recent study, 13 taxa of subfamily Panicoideae were investigated for morphological characterization of caryopsis. Light microscope (LM) and scanning electron microscope (SEM) were utilized to study macro‐ and micro‐morphological caryopsis features respectively. Caryopsis size in studied taxa was recorded as 1.5–10 mm long and 1–4 mm wide. Caryopsis color was brown, green, yellow, and whitish‐brown. Caryopsis shape studied was obovate, elliptic, linear oblate, and round shallowly obtriangular. Hilum position is grooved and depressed. Caryopsis compression type was lateral and dorsiventral. Major variations among studied taxa were observed in terms of caryopsis surface pattern and epicuticular projection types. Six types of caryopsis surface pattern were observed viz. scabrate, rugose, striate, reticulate, papillate, and scabridulous. Structures such as silica cells, bulges, spines, prickles, granules, and bicellular microhair were studied as epicuticular projections. Major variations were observed among Cenchrus pennisetiformis and Cenchrus ciliaris as both has entirely two different types of surface patterns and epicuticular projections. Anticlinal wall thickness and pattern as well as periclinal wall texture and level were investigated. The present research work emphasized on caryopsis characterization of subfamily Panicoideae and it is recommended to establish phylogeny within subfamily Panicoideae and with other subfamilies of Poaceae.     

Charging control using pulsed scanning electron microscopy

This paper describes a novel method to observe highly charging specimens at high-beam voltages without specimen preparation. It is found that the technique greatly reduces charging artifacts such as image shift, astigmatism, and defocussing without sacrificing image quality. Images obtained of uncoated specimens are found to be comparable to gold-coated specimens and without exhibiting charging effects. The technique also allows the study of charge distribution effects in specimen charging of which very little understanding exists, particularly as far as the spatial and time-dependent properties of charging are concerned.     

Observations of snow crystals using low-temperature scanning electron microscopy

Low-temperature scanning electron microscopy (SEM) was used to observe precipitation particles commonly known as “snowflakes.” The snowflakes were collected in Beltsville, Maryland, at temperatures ranging from ?6° to +1°C, mounted on SEM stubs, frozen in liquid nitrogen (LN₂), and then transferred to a cryosystem mounted on a field-emission SEM. Neither sputter coating with platinum nor irradiation by the electron beam affected their delicate fine structure. SEM observations revealed that snowflakes consisted of aggregations of snow crystals that occurred as hexagonal plates, prismatic columns, needles, and dendrites. In some cases, the snow crystals contained minute surface structures that consisted of rime, microdroplets, short prismatic columns, and amorphous films. Snow crystals from wet snow, which were collected at temperatures of 0° and +1°C, exhibited varying degrees of metamorphism or melting. The discrete crystalline faces and their sharp intersecting angles were gradually replaced by sinuous surfaces that tended to exhibit more spherical shapes. This study indicates that low-temperature SEM is a valuable technique for studying the formation and metamorphosis of snow crystals. The results suggest that combining low-temperature SEM and x-ray analysis could also provide qualitative elemental information on the nucleation particles of snow crystals as well as on the composition of acid snow.     

Detailed macro and micromorphology of grasses caryopsis using scanning electron and light microscopy

Micromorphology of 15 grass caryopsis was investigated through scanning electron microscopy for its implications in the identification of grasses. Both macro and micromorphological characters especially caryopsis shape and surface morphology were found significant in the taxonomic diagnosis. Shape morphology of caryopsis varied among the species and lanceolate, fusiform, narrow ellipsoidal, ovate, elliptical, plano-convex, fusiform, linear ovate, broadly elliptical, broadly pllipsoidal, plano-convex, oblique ovate, and subglobose shapes were recorded. Digitaria nodosa (3.31 × 0.7 mm) and Echinochloa crus-galli (3.26 × 1.44 mm) had the largest caryopsis size, while Acrachne racemosa (0.76 × 0.54 mm) and Eragrostis minor (0.62 × 0.38 mm) had the smallest caryopsis size. Macro and micromorphological characters were useful for the diagnosis of genus and species. Utilizing both qualitative and quantitative character taxonomic key at generic and species level were made.     

The effect varied scanning electron microscopy desiccation techniques has on demineralized dentin

The study objective was to assess (a) the effect of a rubbing‐application of ethylenediaminetetraacetic acid (EDTA) or citric acid (CA) has on the ultrastructure of surface dentin and (b) the effect of two scanning electron microscopy (SEM) desiccation preparation techniques have on the collagen surface produced. Treatment regions on proximal root surfaces of extracted human teeth were root planned to expose dentin. Cotton pellets soaked in either 30% CA or 24% EDTA solution were rubbed on the treatment region then processed for SEM using one of two desiccation techniques, that is, (a) critically point dried from liquid CO₂ (control) or (b) air‐dried from tetramethylsilane (experimental). Specimens were coated with gold/palladium and viewed/photographed with an SEM. Specimens of the control groups displayed tufted fibrils (CA > EDTA) with many dentin tubules being partially obscured by overhanging fibrils. Air‐dried specimens of both treatment groups displayed a flat intact monolayer devoid of a matted meshwork of fibrous collagen. Discrete fibril “sprigs,” emanating from the surface monolayer, were characteristic of the EDTA group only. The rubbing‐application of EDTA on dentin produces a tufted fibril surface somewhat similar to that produced by CA. Air‐drying desiccation of both resulted in marked distortion with fibril collapse/coalescence of the tufted collagen matrix.     

Pollen morphology and its taxonomic potential in some selected taxa of Caesalpiniaceae observed under light microscopy and scanning electron microscopy

Pollen micromorphology is not only used to check the functional and structural evolution in plants but also to solve the taxonomic problem related to the classification of plants. Therefore, keeping in view the significance of pollen traits, selected taxa of the subfamily Caesalpiniaceae was collected from different geographical regions of Pakistan. The species were then analyzed under both light microscopy and scanning electron microscopy techniques to investigate the importance of micromorphological characters of pollen in the identification and classification of species. Great variation was recorded in equatorial shape, surface ornamentation, tectum, polar diameter, equatorial diameter, and exine thickness. However, little variation was observed in pollen type, polar shape, and fertility of pollen. The equatorial shape of five types was observed: prolate, prolate-spheroidal, spheroidal-subprolate, subspheroidal-prolate, and subspheroidal. Four types of surface ornamentation, psilate, granulate, clavate, and perforate, were recorded. Tectum of five types, intactate, reticulate regulate, medium reticulate, tactate, and striate, was observed. Sexine was thicker than nexine in all studied species. The largest polar diameter was observed in Caesalpinia pulcherrima 64.1 μm while the smallest in Parkinsonia aculeata 26.1 μm. The largest equatorial diameter was found in C. pulcherrima of 70.25 μm whereas the smallest in P. aculeata 27.57 μm. All the pollens analyzed were tricolporate. All studied species have a fertility ratio of more than 90%. A taxonomic key was developed to show the variation in pollen features and delimit species for the correct identification. In conclusion, the pollen traits were found useful to define species boundaries at various taxonomic ranks and will strengthen the taxonomy of this subfamily. Besides, this study also explored the palynological traits and their implication in the taxonomy of the subfamily Caesalpiniaceae.     

Functional and comparative study of lingual papillae in four species of bear (Ursidae) by scanning electron microscopy

The eight current species of bear (Ursidae) are widely distributed throughout Europe, Asia, and America. They are mainly encountered in the northern hemisphere, except for the spectacled bear and the sun bear, which are also found in the south of the equator. Adaptations of the masticatory apparatus (teeth, tongue, and musculature) to diet are one of the factors that imply the greatest structural changes in the cranium. This diet may be carnivorous, herbivorous, melliferous, or insectivorous, with one type of food predominating according to the time of year. The way in which food is eaten determines the morphology of the lingual surface; generally speaking, all bears put their mouth to the food, which, initially, they lick or they let the food stick to their tongue, as occurs when insects are eaten. As in all mammals, a distinction can be made between mechanical and gustatory papillae and the development and distribution of which depend on the species and their eating habits. In this study of the complete tongues of four species of adult bears, we describe the morphology of the lingual surfaces, the different types of papillae, their characteristics, and topographic distribution. It was seen that there were five main types of lingual papillae: filiform, conical, fungiform, foliate, and vallate. Morphology of the microgrooves and pores was similar to that observed in other mammals. In general, there were no great differences among the four species of bears studied, perhaps due to the similarity in the kind of food they consume in captivity.     

A procedure for rupture-free preparation of confluently grown monolayer cells for scanning electron microscopy

Monolayers of PtK-1 and HeLa cells grown on glass or plastic supports are extremely susceptible to lacerations, e.g., splits and cracks caused mainly by shrinkage when prepared for scanning electron microscopy (SEM). We find that a four-step fixation procedure including glutaraldehyde, OsO₄, tannic acid, and uranylacetate application, in combination with critical point drying, drastically reduces these structural damages. In addition, the conductivity of the specimens is enhanced, so that they can be investigated without gold coating. Transmission electron microscopy (TEM) investigation of perpendicular sections in the area of lacerations provides evidence that the subcortical cytoskeletal elements are of crucial importance in maintaining cell membrane stability during the preparations. Our relatively quick and simple procedure results in an improved structural appearance of the cells.     

The development of the tongue of the domestic goose from 9th to 25th day of incubation as seen by scanning electron microscopy

The general development of the tongue in birds was described by Lillie ( 1908 ) in chicken. Bryk et al. ( 1992 ) also studied the tongue development in chicken and they observed development of the conical papillae of the body. Our study aims to describe the timing of the development of the tongue morphological features in the domestic goose by using SEM methods. The tongue of the domestic goose is characterized by the widest variety of shape of the particular part of the tongue and mechanical papillae. Results indicated that the formation of the apex, body, lingual prominence, and the root of the tongue take place between the 10th and 19th day of incubation. The tongue elongates rapidly between the 16th and 18th day of incubation. Simultaneously, the median groove appears on the body and the lingual prominence and elongates towards the rostral part of the tongue. The conical papillae of the tongue develop gradually. On the body, the conical papillae develop from the caudal part of the body to the rostral part and on the lingual prominence from the median part of the prominence to the lateral part. Hair‐like papillae at the caudal surface of the body of the tongue remain primordial to the end of the incubation. Our studies on the morphogenesis of the tongue in the domestic goose revealed changes in shape of the particular part of the tongue and rapid pace of the formation of mechanical papillae. The tongue is completely develop before hatching and ready to collect food. © Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.     

Morphological investigations on the lips and cheeks of the goat (Capra hircus): A scanning electron and light microscopic study

The current study was done to provide comprehensive information on the anatomical features of the lips and cheeks of the goat by gross examination and morphometric analysis in addition to scanning electron microscope (SEM). Samples from 12 normal healthy adult goat's heads of both sexes were collected directly after slaughtering. The lips and cheeks were dissected, and specimens were collected for both light and SEM. The lips of goat were soft and mobile. The free border of both lips was characterized rostrally by the presence of labial projections. The number, size, and arrangement of labial projections differed in the upper and lower lips. On the other hand, the buccal papillae were arranged into 6–8 longitudinal rows parallel to the cheek teeth. The length of these papillae decreased caudally while they were absent on the most caudal part of the cheek. Presence of several types and shapes of labial projections and papillae, and buccal papillae suggest a high degree of mechanical adaptation of the lips and cheeks of the goat. This study provides baseline data for clinical studies. This study is the first report to shed light on the morphology of the lips and cheeks of the goat by gross and scanning electron microscopy.     

Porosity variation in hydroxyapatite and osteoblast morphology: a scanning electron microscopy study

The biocompatibility of hydroxyapatite has been demonstrated by previous studies, with enhancement of osteointegration through the use of porous hydroxyapatite (pHA). Emphasis has been focused on the use of coralline hydroxyapatite or the introduction of macroporosity into synthetic hydroxyapatite. The current study investigates the role of macro‐ and microporosities in synthetic phase‐pure porous hydroxyapatite on the morphological aspects of human osteoblast‐like cells using scanning electron microscopy. Cells were seeded on four different types of porous hydroxyapatite (HA1, HA2, HA3 and HA4) and examined following 1, 2, 14 and 30 days of incubation in vitro. The results indicated that the cells had an affinity to micropores through filopodia extensions, at initial stage of attachment. Cellular proliferation and colonization was evident on all materials with cells forming cellular bridges across the macropores at day 14 with cellular canopy formation covering entire macropores observed by day 30. This study demonstrates that while the introduction of microporosity has no evident effect on cellular morphology at later time points, it seems to play a role in initial cellular anchorage and attachment.     

Deconvolution of scanning electron microscopy images

This paper describes a method of removing blurs in scanning electron microscopy (SEM) images caused by the existence of a finite beam size. Although the resolution of electron microscopy images has been dramatically improved by the use of high-brightness electron guns and low-aberration electron lenses, it is still limited by lens aberration and electron diffraction. Both are inevitable in practical electron optics. Therefore, a further reduction in resolution by improving SEM hardware seems difficult. In order to overcome this difficulty, computer deconvolution has been proposed for SEM images. In the present work, the SEM image is deconvoluted using the electron beam profile estimated from beam optics calculation. The results show that the resolution of the deconvoluted image is improved to one half of the resolution of the original SEM image.