Compositional changes of the xiphoid process and costal cartilage with aging

Because zinc attenuates endothelial cell dysfunction that proceeds atherosclerosis, depressed zinc status may be involved in the initiation of endothelial dysfunction. However, before recommending a zinc-enriched diet to reduce the risks for atherosclerosis, the effect of excess zinc on endothelial cell functions in normozincemic status should be known. Therefore, in this study, the effect of dietary zinc on normal endothelial cell functions in animals subjected to a diet containing 334±58 ppm zinc for 30 d was studied to see whether supplemented zinc has an effect on endothelial cells. Despite a slight increase in blood zinc, unaltered aortic and kidney zinc contents were associated with unchanged blood pressure in rats subjected to a zinc-enriched diet. Increased basal nitric oxide and prostacyclin were accompanied by a normal response to phenylephrine. Dietary zinc influenced neither endothelial-dependent nor endothelial-independent relaxations significantly. However, it elevated the share of M1-type cholinoceptor response as well as dilator prostaglandin release, which seems to be nitric oxide dependent. There was a strong correlation (r=0.826, p<0.05) between M1-type cholinoceptor response and prostacyclin release in zinc-treated rings. These results suggested that zinc ions increases M1-mediated prostacyclin release in normal endothelial cells without altering intracellular pathways.     

Light and electron microscopical investigations on shell pores (caeca) of fissurellid limpets (Mollusca: Archaeogastropoda)

The organic content (caecum) of the shell pores of five species of fissurellid (key-hole) limpets was investigated by means of light and electron microscopy. Fissurellid caeca are unbranched, polycellular extensions of the mantle epithelium, which penetrate the whole shell and contact the periostracum via organic fibres called 'brush'. They are built up by two cell-types, which enclose a central lumen, and are formed concurrently with the shell itself. Because of fundamental structural and developmental differences, the superficially similar shell pores of bivalves (caeca) and polyplacophorans (aesthetes) are considered as analogous rather than homologous organs. Similarities are found with brachiopod caeca, probably owing to similar functions.     

Effects of ionizing radiation and preservation on biomechanical properties of human costal cartilage

Tissue banks around the world store human cartilage obtained from cadaveric donors for use in diverse reconstructive surgical procedures. To ensure this tissue is sterile at the time of distribution, tissues may be sterilized by ionizing radiation. In this work, we evaluate the physical changes in deep frozen costal cartilage (?70 °C) or costal cartilage preserved in high concentrations of glycerol (>98 %) followed by a terminal sterilization process using ionizing radiation, at 3 different doses (15, 25 and 50 kGy). Tension and compression tests were carried out to determine the mechanical changes related both to the different preservation methods and irradiation doses. For both methods of preservation, tension strength was increased by about 24 %, when cartilage tissue was irradiated with 15 kGy. Deep frozen samples, when irradiated with 25 or 50 kGy, had a decrease in their mechanical performance, albeit to a lesser extent than when tissues were preserved in high concentration of glycerol and equally irradiated. In conclusion, processing in high concentration of glycerol did not increase tissue protection against radiation damage; while cartilage preserved in high concentrations of glycerol withstands radiation up to 25 kGy, deep frozen human costal cartilage may be sterilized with a doses up to 50 kGy without significant mechanical impact.     

Mallomonas transsylvanica,spec. nova (Chrysophyceae), light and electron microscopical studies

The new speciesMallomonas transsylvanica is described in detail. Its silica armour has been examined by light and electron microscopy. Differences and possible relationships with other species are discussed.     

Areas of asbestoid (amianthoid) fibers in human thyroid cartilage characterized by immunolocalization of collagen types I,II, IX,XI and X

The distribution of type I, II, IX, XI and X collagens in and close to areas of asbestoid (amianthoid) fibers in thyroid cartilages of various ages was investigated in this study. Asbestoid fibers were first detected in thyroid cartilage from a 3-year-old male child. Areas of asbestoid fibers functionally appear to serve as guide rails for vascularization of thyroid cartilage. Alcian blue staining in the presence of 0.3 M MgCl₂ revealed a loss of glycosaminoglycans in areas of asbestoid fibers. In addition, the fibers reacted positively with antibodies against collagen types II, IX and XI, but showed no staining with antibodies to collagen types I and X. Territorial matrix of adjacent chondrocytes showed the same staining pattern. In addition to staining for type II, IX and XI collagens, asbestoid fibers showed strong immunostaining for type I collagen after puberty but not for type X collagen. However, groups of chondrocytes within areas of asbestoid fibers reacted strongly with antibodies to type X collagen, suggesting that this collagen plays an important role in matrix of highly differentiated chondrocytes. The finding that these type X collagen-positive chondrocytes also revealed immunostaining for type I collagen confirms previous studies showing that hypertrophic chondrocytes can further differentiate into cells that are characterized by the synthesis of type X and I collagens.     

Light and electron microscopical observations on sperm cells of Guizotia abyssinica (Asteraceae)

The sperm cells of Guizotia abyssinica were studied during pollen development by light microscopy and at anther dehiscence by transmission electron microscopy. During development, the nuclei change shape from spherical to elongate, thread-like and banded. They are straight or folded, and rarely spiral-shaped when present in the pollen tube. Electron microscopy disclosed that the elongated sperm nuclei are apparently lobate. Intermittently, they are constricted and attenuated or convoluted. The major part of the sperm chromatin is condensed and peripheral, while a minor part is dispersed and central. The scanty sperm cytoplasm contains mitochondria and starch granules. The cytoplasm is mainly restricted to spaces adjoining constricted, lobed and convoluting nuclear sites. Some cytoplasmic patches become embayed in the nucleus at these sites. The periplasm bordering the sperm cells may originate from lucid dilations of the lumen between the plasma membranes of the sperm and vegetative cells. The periplasm is sometimes partially or entirely surrounded by double-membraned endoplasmic reticulum. Folded sperm cells with less coherent periplasm possibly represent a late stage preceding discharge into the pollen tube. The sperm cells always precede the vegetative nucleus into the pollen tube.     

Brachylaima cribbi (Digenea: Brachylaimidae): scanning electron microscopical observations of the life-cycle stages

Brachylaima cribbi is a recently described species of terrestrial trematode that infects mammals and birds with helicid land snails as its first and second intermediate hosts. The adult worm is 2.5-6.0 mm long by 0.5-0.8 mm wide being a long slender cylindrical worm with oral and ventral suckers in the anterior quarter and genital pore in the posterior quarter. Scanning electron microscopy shows that there is a dense covering of tegumental spines at the anterior end which diminishes towards the posterior extremities of the worm. Development of spines was observed in juvenile and mature adult worms. In young worms 1-3 weeks post infection (wpi) spines appear as buds with a serrated edge each having 1-4 spikes per spine. As the worm ages the spines broaden and by 5 wpi the number of spikes per spine increases to an average of 8.1. The serial development of oral sucker papillae in the cercaria, metacercaria and adult worm was observed with the finding of an elongated papilla with a bifurcated tip on the cercaria becoming a shorter and thicker elongated papilla with a large central stoma on the metacercaria. In the adult worm, this papilla becomes dome-shaped with a small central stoma. For some of these papillae a cilium could be seen extended from the central stoma. Other life-cycle stages illustrated were the hatched egg with an extruded egg membrane minus an operculum and a portion of the branched sporocyst dissected from the digestive gland of the land snail Theba pisana showing a terminal birth pore. Scanning electron microscopy morphological features of the adult worm observed for the first time in a Brachylaima were the unarmed cirrus extended from the genital pore with released sperm present and the Laurer's canal opening visible in tegumental folds on the dorsal surface approximately 300 microm posterior to the genital pore.     

Light and electron microscopical studies onHafniomonas gen. nov. (Chlorophyceae,Volvocales), a genus resemblingPyramimonas (Prasinophyceae)

Based on light and electron microscopical studies ofPyramimonas reticulata the genusPyramimonas is shown to contain a number of unrelated flagellates.P. reticulata andP. montana are transferred to the new genusHafniomonas, cells of which differ fromPyramimonas in shape, in the absence of scales and hairs on the body and flagellar surfaces, in details of the chloroplast, the position of the nucleus, the Golgi apparatus, the internal structure of the flagellar apparatus, and in cell division. The prasinophytePyramimonas contains a characteristic association of a large microbody and a rhizoplast, situated on the nuclear surface. A similar association is being found in an increasing number of prasinophycean flagellates, but is absent inHafniomonas, which is considered related to chlorophycean rather than prasinophycean flagellates. The phylogenetic position ofHafniomonas is discussed, based in particular on details of the unique flagellar apparatus.     

Light and electron microscopical immunohistochemical localization of the small proteoglycan core proteins decorin and biglycan in human knee joint cartilage

Summary The distribution of decorin and biglycan was investigated at the light and electron microscopical level in adult human articular cartilage. In general, the amount of decorin and biglycan was found to decrease with the depth of the layer of the cartilage. Decorin was found in the interterritorial matrix where most of the collagen is located. This fits in well with the assumption that decorin may modulate collagen metabolism. Biglycan was found next to the chondrocytes in the pericellular matrix and is assumed to be responsible for cellular activities. At the ultrastructural level, decorin was localized in the interterritorial matrix and in vesicles in chondrocytes. Biglycan was found, usually though not exclusively in the pericellular matrix. Both small proteoglycans were detected close to and on the collagen fibres and also associated with the more globular structures of the matrix between the fibrils. A double-staining approach revealed that the two molecules could be located along the same collagen fibril. However, staining for biglycan and decorin was not observed simultaneously within the same region of the fibre.     

Electron microscopic investigations on aging and osteoarthrotic human articular cartilage

Summary The submicroscopic morphology of freeze-etched aging human articular cartilage is reported. In contrast to chemically fixed and thin sectioned cartilage tissue, chondrocytes and matrix of freeze-etched specimens exhibit new morphological aspects.The surface of superficial chondrooytes shows invaginations and bulges, producing a cauliflower-like appearance of the cell body. Finger-like protrusions as found in thin sections are absent. The matrix adjacent to the pericellular halo, the latter consisting of a fine granular material, is characterized by the presence of globular, membrane-bounded vesicles of variable size. This vesicle containing zone is called corona. The corona vesicles as well as the cellular membranes are occupied by two types of particles (85 and 135 Å in diameter). Based on the presence of these particles, the nature and possible origin of the corona vesicles are discussed.