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Biomedical subjects

H Dalen

Publications and source records attributed to H Dalen.

At least 73 records · Page 4Linked to original sources
PubMed1981

An ultrastructural study of primary cilia, abnormal cilia and ciliary knobs from the ciliated cells of the guinea-pig trachea.

Single primary cilia are found in developing as well as mature ciliated cells of guinea-pig tracheal epithelium. A few biciliated cells were observed, and in a rare case one cell had developed four such processes. Primary cilia are characterized by a 9 + 0 microtubular arrangement near the base, while a transition to an 8 + 1 pattern occurs at a slightly more distal position. Spokes are lacking, and dynein arms are absent or incompletely developed. The function, if any, of primary cilia remains unknown. In the population of the motile 9 + 2 cilia atypical forms are very rare, i.e. less than 0.1%. Of the various abnormalities cilia with supernumary microtubules are most common. Only one atypical basal body was observed. Although some of the aberrant forms undoubtedly are non-motile, their very low number suggests that they have no practical influence on the muco-ciliary clearance. Local extrusions of the ciliary membrane, here named ciliary knobs, are believed to be fixation artefacts. It is suggested that they represent circumscribed regions of the ciliary membrane which are sensitive to changes in the environmental osmotic pressure.

Animals↗
PubMed1981

Patterns in quench-frozen, freeze-dried, blood proteins.

Scanning electron micrographs of whole blood prepared with cryotechnics demonstrated patterns assumed to be artifacts of the freezing process. A SEM investigation of the effects of freezing and freeze-drying on columns of purified blood proteins has been carried out using quench-freezing and cryo-fracturing followed by freeze-drying. Correlative studies with a light microscope and a transmission electron microscope are included. The resulting patterns depended on the type and concentration of protein as well as on the position within the sample and the orientation of the fracture plane relative to the column axis.

Blood Proteins↗
PubMed1980

A correlative transmission and scanning electron microscopic study of the pigeon myocardial cell.

A comparative study of the pigeon ventricular myocardial cell has been performed by transmission electron microscopy (TEM) and by scanning electron microscopy (SEM). Three-dimensional access to the cell interior was obtained by cryo-fracturing paraffin-embedded tissue immersed in liquid nitrogen. The TEM studies revealed parallelly arranged myofibils separated by rows of mitochondria. The sarcoplasmic reticulum is represented by a well-developed network of tubules which, at the Z- and H-band level of the sarcomere, expands to form belt-like cisternae. The cisternae at the Z-band level lie in close proximity to both myofilaments and mitochondria. Transverse tubules are absent and thus only peripheral couplings are present. SEM observations of the fractured tissue revealed the spatial relationship between the different cell organelles, the most important of these being the parallel myofibrils and the mitochondria. The conspicuous ridges transversing the myofibril at the Z-band level consist mainly of expanded Z-bands, but overlying SR-tubules also contribute to these ridges. Traces of the SR can sometimes be seen covering the myofibrils. The close proximity between the SR and the mitochondria was also confirmed in the SEM. Preparation and examination of SEM prepared tissue in the TEM confirmed that no essential damage or reorganization of cell organelles had taken place during tHE SEM procedure. On the other hand some shrinkage of the tissue, which was probably caused by critical point drying, was noticed.

Animals↗
PubMed1979

Middle ear mucosa in cleft palate children. A scanning electron microscopic study.

Twenty-three promontory mucosal specimens from cleft palate children were studied by scanning electron microscope. Comparative studies were made, using light and transmission electron microscopy. The mucosal lining was pseudostratified columnar with microvilli, a few ciliated cells with secretory granules and numerous goblet cells. A few mucous glands, could be seen in certain areas. Microvilli with bulging tips and cilia with microknobs were common phenomena. The submucosa were inflamed, with leukocytes, macrophages, plasma cells and lymphocytes, indicating the presence of both cellular and humeral defence mechanisms.

Child↗
PubMed1978

Cryofracture of paraffin-embedded heart muscle cells.

A comparative study of internal cellular structures of the sheep ventricular myocardium has been conducted by scanning electron microscopy (SEM) and by transmission electron microscopy (TEM). Access to the cell interior for three-dimensional studies was obtained by cryofracturing paraffin-embedded tissue frozen in liquid nitrogen. For accurate localization of structures of special interest thick paraffin sections were examined in the light microscope (LM). Based on the information gained, it was possible to fracture the block in a desired plane. The fracturing was carried out by a light blow to a precooled scalpel held against the surface of the block, which was immersed in liquid nitrogen. After thawing and deparaffinizing at room temperature in several baths of xylene, the tissue pieces were critical point dried using CO2. As xylene was found to be miscible with CO2, it also served as an intermediate fluid. This method resulted in good preservation fo the myofibrils, mitochondria, sarcoplasmic reticulum and transverse tubules (T-tubules), which was confirmed by TEM studies of conventionally prepared tissue and of tissue originally prepared for SEM.

Animals↗
PubMed1975

A comparative study in the transmission electron microscope and scanning electron microscope of intracellular structures in sheep heart muscle cells.

The internal cellular structures of the sheep ventricular myocardium have been comparatively studied in the transmission electron microscope (TEM) and in the scanning electron microscope (SEM). For TEM studies the tissue was prepared according to standard methods. Thick sections (10 mum) of paraffin embedded material were, after they had been deparaffinized in toluene, critical point dried, coated with gold and examined in the SEM. The comparative TEM and SEM investigations revealed very good correspondence, and it is evident that the described preparation procedure for SEM has preserved the fine structures of myofibrils, mitochondria, T-Tubules and sarcoplasmic reticulum in an excellent life-like pattern. Of special interest was the three-dimensional demonstration of triads and circumferentially arranged T-tubules.

Animals↗