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Biomedical subjects

A Köling

Publications and source records attributed to A Köling.

At least 19 recordsLinked to original sources
PubMed1990

High-resolution scanning electron microscopy of the murine olfactory receptor.

The anatomy of the murine olfactory receptor was analyzed using high-resolution scanning electron microscopy with the aldehyde-osmium-dimethyl sulfoxide-osmium method. A good three-dimensional image of the receptor cell architecture was obtained. Within the olfactory vesicle, a complex tubular network was found that seemed to be physically associated with adjacent organelles, the basal aspect of cilia, and the lateral plasmalemma. It is assumed that these structures may be of significance during the olfactory transduction process.

Animals↗
PubMed1987

Freeze-fracture electron microscopy of simultaneous odontoblast exocytosis and endocytosis in human permanent teeth.

Replica preparations of dental pulp revealed membrane specializations indicating both exocytosis and endocytosis in the apical part of the odontoblast cell body and the proximal part of the odontoblast process. In tangential fractures, the plasmalemma exhibited protruding spheroids, considered to be the final stage in exocytosis. Other stages observed were plasmalemmal elevations covering underlying vesicles and surrounded by particle-free zones and fusion between vesicles and the cell membrane. Features indicative of endocytosis were plasmalemma studded patchwise with small circular craters 60-70 nm in diameter, often in association with intramembranous particles, and clusters of particles, probably constituting the sites of initiation of endocytotic vesicles in the plasmalemma.

Adolescent↗
PubMed1985

Membrane architecture of myelinated nerve fibres in the human dental pulp studied by freeze-fracturing.

The outer surface of the myelin sheath was well visualized in electron micrographs of replicas and the distribution of its cytoplasm-containing portions could be analysed. Numerous caveolae, probably representing the surface stomata of endo- or exocytotic vesicles were found on the plasmalemmal surface overlying organelle-rich cytoplasmic regions. Membrane specializations of the tight-junction type were found at the outer and inner mesaxons of the myelin sheath as well as at the Ranvier node and Schmidt-Lanterman incisures. Presuming that so-called leakiness is related to the junctional morphology, these junctions would be classified as moderately leaky. The morphological features of the Schwann-cell nuclear envelope were essentially as described for other mammalian cells.

Adolescent↗
PubMed1985

Freeze-fracture electron microscopy of non-myelinated nerve fibres in the human dental pulp.

Freeze-fracture replicas from the subodontoblast region gave a good three-dimensional comprehension of the structure of non-myelinated nerve fibres. Each Schwann cell ensheathed 1-15 axons with a mean diameter of 0.4 micron (0.1-1.2 micron). Many axons were not entirely ensheathed but were exposed to the extracellular space to various degrees. Tightening membrane specializations were not found in the mesaxons. The Schwann-cell plasmalemma exhibited caveolae with necks surrounded by evenly-sized intramembranous particles, typical of endocytosis. The nuclear envelope of Schwann cells showed a few typical pores and perinuclear cisterna. In tangential fractures, the axolemma displayed intramembranous particles evenly distributed over the axolemmal fracture planes. There was a marked difference in particle density between the P (600-650/micron2) and E (150-200/micron2) faces.

Adolescent↗
PubMed1985

Freeze-fracture electron microscopy of the nuclear envelope of the human odontoblast.

The nuclear envelope was studied in several planes on freeze-fracture replicas. The inner and outer nuclear membranes were similar. Each presented two fracture faces, one with a higher intra-membranous particle density than the other. The perinuclear cisterna was bounded by outer and inner nuclear membranes about 40 nm apart. The nuclear pores of 85 nm diameter were evenly distributed over the nuclei. The pore density (5/micron2) was low compared with that in many other cells, but was of the same magnitude as is reported for the rat odontoblast.

Adolescent↗
PubMed1985

The ultrastructure of the human antral mucosa as demonstrated by freeze-fracturing.

The fine structure of the normal mucous membrane in the human maxillary sinus was investigated by means of the freeze-fracture technique. Special interest was directed to membrane structures in the epithelial cells. The morphology of tight junctions could be analysed. According to morphological criteria these junctions might be classified as "very tight". So called ciliary necklaces were well distinguishable. Their morphology seemed to be in concordance with the structure reported in other mammalian respiratory epithelia. Abluminally the epithelial cells frequently displayed abundant caveolae or micropinocytotic vesicles. The present investigation was performed as a preface to later studies on pathologically altered antral mucosa.

Cilia↗
PubMed1984

Membrane structures in the pulp-dentin border zone. A freeze-fracture study of demineralized human teeth.

The membrane morphology of cells in the pulp-dentin border zone in human teeth was scrutinized by means of the freeze-fracture technique. The tissue was fractured and replicated after mild demineralization in Na-EDTA. This procedure did not seem to influence the preservation of the tissue significantly. The odontoblastic cell bodies and their long processes lying within the predentinal and dentinal tubules were exposed. The technique made it possible to analyze the structural features of the apical part of the odontoblastic layer, including the 'terminal bar' region. This area exhibited large, irregularly shaped gap junctions. In some regions clusters of many small membranous pits or caveolae apparently representing pinocytotic vesicles were seen. The odontoblastic process displayed membrane protuberances projecting outward and abutting the inner tubular wall. In the predentinal and the adjacent dentinal regions, fine-caliber fibers (approximately 0.1-0.4 micron in diameter), presumably nerves, appeared in intimate relationship with the odontoblastic cell processes. At these sites the cell membrane displayed aggregations of membrane-associated particles, presumably gap junctions.

Adolescent↗
PubMed1984

Membrane junctions between odontoblasts and associated cells. A freeze-fracture study of the human odontoblastic cell layer with special reference to its nerve supply.

The relationship between odontoblasts and adjacent cell structures within the odontoblastic cell layer was analyzed by means of the freeze-fracturing technique. Two principal forms of interodontoblastic cell structures were found. The first was tubular or thread-like in appearance, having a general diameter around 0.1-1.0 micron. From morphological criteria these were believed to represent small, unmyelinated nerve fibers. The second type of cell structure found between odontoblasts was more irregular and heterogeneous in outline, and often lamellar or branched. These slender formations sometimes proved to constitute cellular projections from adjacent odontoblasts or neighboring, subodontoblastic fibroblasts. Both the nerve-like fibers and the irregular branched cells between the odontoblasts showed morphological contact areas with odontoblastic cell bodies. At these sites the intracellular distances were reduced, and characteristic gap junctional complexes occurred. Nerve ending specialization or membrane structures indicating the presence of chemical synapses on the odontoblastic cell surface were not observed.

Adolescent↗
PubMed1983

Membrane junctions in the subodontoblastic region. A freeze-fracture study of the human dental pulp.

The morphology of the subodontoblastic region in the human dental pulp was analysed using the freeze-fracturing technique. Multiple areas of focal intercellular junctions were found between subodontoblastic fibroblasts (or Höhl's cells). The connections were of the gap junction type. Similar junctions were observed between subodontoblastic cells and small-calibre (0.10-0.20 microns) fibres, presumably nerves. Tight junctions were not observed.

Adolescent↗
PubMed1983

The blood capillaries in the subodontoblastic region of the human dental pulp, as demonstrated by freeze-fracturing.

The microvasculature of the subodontoblastic region in the human dental pulp was studied, using freeze-fracturing. This technique allows an analysis of the fine structure of the vascular endothelium with special reference to the membrane structure. The blood capillaries were noted to be of the non-fenestrated or continuous type, although a few fenestrated vessels were observed. The endothelial plasmalemma often exhibited bundles of fibrillar structures, presumably myofilaments. There was a relatively large number of micropinocytotic vesicles and the interendothelial spaces were closed juxtaluminally by tight junctions (zonulae occludentes). The junctions appeared mostly as two to four strands, seen as ridges or grooves on the cell membrane. Thin-walled, irregular, tissue channels lacking the typical, blood-vessel configuration were disclosed. These vessels were believed to represent lymphatics.

Capillaries↗
PubMedDate not supplied

A freeze-fracture study of receptor axons and Schwann cells in the human olfactory mucosa.

Electron micrographs of freeze-fracture replicas from the human olfactory mucosa were analysed regarding the structure of the axons of the olfactory receptor cells. In the lamina propria, numerous axons were generally invested with one Schwann cell. The ensheathed axons were often found in close contact with one another. Membrane specializations were not found at these sites, nor were tightening membrane junctions observed in the mesaxons. The Schwann cell plasmalemma exhibited caveolae, whose neck was surrounded by uniformly sized intramembranous particles evenly distributed over the axolemmal fracture planes. There was a marked difference in particle density between the P face (about 850/micron 2) and the E face (about 180/micron 2).

Axons↗