Electron Microscopy

The columella cells of soybean roots grown under gravity and simulated microgravity induced by a clinostat were examined using potassium pyroantimonate (PA) and quantitative X-ray microanalysis of cryosections to determine the role of Ca in the regulation of the gravitropic response. Amyloplasts in the columella cells were localized exclusively at the bottom under gravity, but diffusely distributed in the cytoplasmic matrix under simulated microgravity, thus supporting the statolith theory. In the columella cells, PA precipitates containing Ca were diffusely distributed in the cytoplasmic matrix under gravity. Under simulated microgravity, however, they decreased in number and size in the cytoplasmic matrix, whereas increased only in number in the vacuole, indicating that Ca moved from the cytoplasmic matrix into the vacuole. The vacuole of columella cells contained mostly electron-dense granular structures localized along the inner surface of tonoplasts, which closely resembled the tannin vacuole reported in Mimosa pulvinar motor cells. Under simulated microgravity, their configuration changed dramatically from a granular shape to a flat plate. The quantitative X-ray microanalysis of cryosections showed that the vacuolar electron-dense structures contained a large amount of Ca. Under simulated microgravity, the concentration of Ca increased conspicuously in these vacuolar electron-dense structures, concomitantly with a marked decrease of K in the vacuoles and an increase of K in the cell walls. These results suggest that the release of Ca²⁺ from, and uptake by, the vacuolar electron-dense structures is closely related to the signal transmission in the gravitropic response and that Ca movement occurs opposite to that of K.

Urolithiasis is a common diagnostic and therapeutic problem in small-animal veterinary practice. The traditional diagnostic approach usually consists of clinical, radiological and ultrasonographic examination of the patient. The main diagnostic material is still urine sediment, ignoring the fact that presence of crystalluria is not always of pathological significance. In order to establish the most effective therapeutic and preventative strategies, especially in the case of multicomponent stone, it is crucial to define the exact elemental composition of the given stone including crystallization nidus chemical contents. In the course of the research, the usefulness of scanning electron microscopy combined with X-ray-dispersive spectrometry in analysis of canine mixed and compound stones was investigated. The obtained results indicated that the tested method allows one to trace the dynamics of the crystallization process, including crystallization nucleus detection, and concurrently and quantitatively assess the elemental composition of the given urinary concrement. Moreover, the conducted research showed epidemiological data of urolithiasis occurrence in a population of dogs coming from the southern part of Poland.

Age-related morphological and anatomical changes were investigated by light and electron microscopy with juvenile and adult leaves of Dendropanax morbifera. Most juvenile leaves were glossy and palmate with five deep and narrow lobes divided nearly to two-thirds of the leaf base. Adult leaves were thick and possessed three lobes divided nearly to half of the leaf base. Stomata were ovoid and found on the abaxial surface. The epicuticular waxes of the plant included platelets, angular rodlets and threads. Platelets were attached to the surface at various angles. Distinct angular rodlets could be found on either the adaxial or the abaxial surface. Platelets on surface undulations occurred exclusively on the abaxial surface of adult leaves. Juvenile leaves were ca. 150 μm thick and had few intercellular spaces. Adult leaves were nearly two times thicker than juvenile leaves, and showed highly vacuolated cells and large intercellular spaces. The cuticle proper was apparent on the epidermis and showed distinctly alternating lamellate structures in juvenile leaves. The epidermal cell wall of adult leaves was covered with a cuticle layer for which a lamellate structure was not found. These results suggest that the species is heteroblastic in leaf characteristics with increasing leaf age.

A novel method has been developed for preparing in situ straining samples for transmission electron microscopy (TEM) to study dislocation behaviour, here transmission through phase interfaces. A dual-beam focussed ion beam microscope was used to extract oriented foils from locations with specific crystallography in a sample area which had been selected using electron backscattered diffraction (EBSD). The foil was attached to a pre-prepared substrate which was then strained in a transmission electron microscope. The method has been demonstrated successfully by studying <c + a> dislocation transmission through α/β interfaces in a commercial Ti–6Al–4V alloy. However, bending of the foil prevented the actual transmission from being further characterized.

The electron intensity of a beam from an amorphous surface layer on a crystal transmission electron microscopy (TEM) specimen has been found to have sufficient coherence to produce fringes in interferograms, created by interfering two electron diffracted beams from the crystal, using a method of electron interference referred to as diffracted beam interferometry. This interference method involves amplitude splitting of the electron beam by means of a crystal with a thin amorphous layer on its surface. The amorphous intensity is transferred along with the crystal's Bragg diffracted beams and is then self-interfered when the crystal's Bragg diffracted beams are interfered by an electron biprism. The interference fringes in the interferograms exist in low to high electron scattering angles. The spatial frequency of the amorphous intensity fringes depends on the Bragg angle of the crystal's interfered diffracted beams. It is shown that the absolute phase of the amorphous intensity is possibly obtained using a Cs-corrected TEM and two interfering diffracted beams having equal but opposite phases. This method of interference is a good step towards measuring the phase of amorphous materials that is useful in determining their complex atomic structures.