[Ultrastructure of diatom Synedra acus subsp. radians as revealed by transmission electron microscopy after mild silica dissolution].

A diatom Synedra acus subsp. radians (Kütz.) Skabitsch. has been studied by transmission electron microscopy. Examination of ultrathin sections demonstrated that silica dissolution in ammonium fluoride pH 5 under mild conditions leaves the key ultrastructural elements intact. The ultrastructure and arrangement of the cell organelles was studied during ontogeny. Silicalemma-surrounded silica deposition vesicles (SDVs) with maturating daughter valves and forming girdle bands have been identified. This method of SDV visualization offers considerable advantages over the standard approach without silica dissolution.

Small intestine wall distribution of elastic stiffness measured with 500 MHz scanning acoustic microscopy.

Obtaining data relating intestinal mechanical properties and histology is a step towards the next level in the hierarchy of structure of living tissue, and may provide new insight into the mechanisms of intestinal function and disease such as obstruction. Due to lack of methodology, however, such data are currently sparse. Scanning acoustic microscopy (SAM) can measure the propagation speed of sound (C) and the acoustic impedance (Z) with micrometer resolution in tissue. By use of elementary theory of elasticity, the elastic stiffness (c11) can be computed from C and Z. We used 5-microm-thick transverse sections of ethanol treated guinea pig small intestine as the experimental model and measured the distribution of C and Z across the intestinal wall using SAM at 500 MHz. The individual layers mucosa, submucosa, and circular and longitudinal muscle were discerned with ease in the images and varied significantly with respect to both C and Z in most cases. The measured values (median values) of C ranged from 1550 to 1669 m s(-1), and Z ranged from 2.10 to 2.60 MPa s m(-1). c11 differed between all layers ranging from 3.25 to 4.27 GPa with the following sequence of magnitude: circular muscle >submucosa>mucosa>longitudinal muscle (p<0.001). In conclusion, we provided the first microscale mechanical data relating to the histological layers of the small intestine.

[Synovial membrane and cartilage changes in an arthrosis model. Instability and impact stress model]. / Synovialmembran und Knorpelveränderungen im Arthrosemodell. Instabilitäts- und Stoss-Belastungsmodell.

UNLABELLED: Surgical instability and repetitive impulsive loading was used to generate degenerative changes in knee joints of rabbits. Light- and electronmicroscopy was carried out at synovial membrane and cartilage samples. The instabilised joints had early synovial inflammation, preceding overall cartilage changes. Synoviocytes were activated and showed more and dilatated cytoplasmatic organells. Invaded round cells--potentially cartilage degenerative--were seen. In the loading model no initial synovial inflammation could be seen. Focal cartilage changes were located at the weight bearing zone. Two different inductive pathways may be involved in cartilage breakdown comparing the two arthrosis models. Mechanical factors seemed to trigger cartilage changes in the loading model, an inflammatory synovial pathway is likely to initiate cartilage breakdown in the instability model. CLINICAL RELEVANCE: The synovial membrane has the key-position for the cartilage degeneration in posttraumatic joint affections. The therapeutic use of antiphlogistic substances is indicated to supreme inflammatory mediators from the synovial membrane. This therapeutic concept seemed not to be useful in primary mechanical induced osteoarthrosis.