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Biomedical subjects

P Havinga

Publications and source records attributed to P Havinga.

7 recordsLinked to original sources
PubMed1986

Collagenous network in cartilage of human femoral condyles. A light microscopic and scanning electron microscopic study.

To determine the spatial arrangement of collagen fibrils in articular cartilage of the human femoral head, three healthy femoral heads, obtained at necropsy, were examined by light microscopy and scanning electron microscopy. Light microscopic observations revealed no collagen fibril organization. Scanning electron microscopic observations showed a fine fibrillar texture throughout the articular cartilage. At the articular surface, smooth and fibrillated areas were detectable. Underneath the articular surface, the collagen network in the superficial zone showed a tighter appearance when compared with the homogeneous collagen network of the matrix in the deeper zones. The calcified cartilage zone was well demarcated from the uncalcified cartilage. The arcade model of Benninghoff [Z. Zellforsch. Mikrosk. Anat. 2: 783-862 (1925)] could not be confirmed. It was concluded that the organization of collagen fibrils in hyaline cartilage shows a three-dimensional network of randomly oriented fibrils.

Adult↗
PubMed1986

Fluid secretion in arachnoid cysts as a clue to cerebrospinal fluid absorption at the arachnoid granulation.

The morphological similarity of the lining of arachnoid cysts to subdural neurothelium and the mesothelium of arachnoid granulations suggested that the latter tissues might be the origin of arachnoid cysts. Transport Na+-K+-adenosine triphosphatase was shown by enzyme ultracytochemistry to be an indication of secretory activity in the lining of arachnoid cysts and in the endothelial lining of arachnoid granulations. This secretory activity suggests the existence of a biochemical mechanism for cerebrospinal fluid absorption at these granulations separate from the mechanisms already demonstrated.

Absorption↗
PubMed1985

Osteoarthritis of the temporomandibular joint: a light microscopic and scanning electron microscopic study of the articular cartilage of the mandibular condyle.

The aim of this study was to investigate the organization of collagen fibrils and the histopathologic alterations as well as the morphologic aspects of osteoarthritic articular cartilage of the human mandibular condyle. Nine osteoarthritic condyles, three obtained at necropsy and the other six during surgery, were examined by light microscopy and scanning electron microscopy. Light microscopic observations revealed features of progressive and regressive remodeling and the presence of clefts. Scanning electron microscopic observations showed the presence of thick, coiled fibrils at the joint surface and numerous osmiophilic lipid globules scattered between the collagen fibrils. The collagen fibrils were disordered. It was concluded that collagen fiber network disintegration and fatty degeneration comprise the osteoarthritic changes of the articular cartilage of the human mandibular condyle.

Adult↗
PubMed1984

Spatial arrangement of collagen fibrils in the articular cartilage of the mandibular condyle: a light microscopic and scanning electron microscopic study.

To determine the spatial arrangement of collagen fibrils in articular cartilage of the human mandibular condyle, ten healthy condyles obtained at necropsy were examined by light microscopy and scanning electron microscopy (SEM). Observations using light microscopy showed the existence of four different zones. The organization and alignment of the collagen fibrils were different in every zone and varied from layers to bundles of fibrils running parallel, obliquely, or radially to the articular surface. Observations using scanning electron microscopy revealed a thin, surface layer of disorganized small fibrils with a cotton-wool appearance and a well-organized architecture of collagen fibrils in every zone. It was concluded that the organization of collagen fibrils in articular cartilage shows a three-dimensional network with a special system in every zone.

Adult↗
PubMed1984

Quantitative cement solubility experiments in vivo.

The dissolution and dissolution rate of dental luting cements was measured longitudinally. Cement samples in enamel were placed in a full prosthesis and worn in the mouth for up to 6 months. At given intervals, replicas of the cement surfaces were made and quantified by means of SEM stereographic photographs. With a stereometer the distance between cement surface and original enamel surface can be determined quantitatively. The results show in vivo solubility rates for zinc-phosphate and glass-ionomer cement of about 80 microns week-1 and 2 microns week-1 respectively.

Animals↗
PubMed1984

Arachnoid cysts of the sylvian fissure. Evidence of fluid secretion.

Morphological and enzyme ultracytochemical evidence is presented to support the contention that the walls of arachnoid cysts secrete fluid. Clinical evidence has already suggested this phenomenon, including intracranial pressure elevation and expansion in some cases, and the observation that arachnoid cysts constitute closed compartments with a fluid content that cannot be derived from other cerebrospinal fluid-containing spaces. Ultrastructurally, the cyst lining showed a similarity to subdural neurothelium and the neurothelial lining of arachnoid granulations in such morphological features as intercellular clefts with sinusoid dilatations, desmosomal intercellular junctions (upon which tonofilaments may be abutting), pinocytotic vesicles, multivesicular bodies, lysosomal structures, and the presence of a basal lamina. Some of these features, together with the presence of microvilli on the luminal surface, are consistent with fluid secretion. Moreover, enzyme cytochemistry demonstrated (Na+ + K+)-ATPase in the plasma membranes lining the cavity, either directly (the apical membranes), or via the intercellular clefts (the basolateral membranes), and, with alkaline phosphatase occupying the opposite plasma membranes, this structural organization indicates fluid transport toward the lumen. It may be surmised that arachnoid cysts derive from subdural neurothelium differentiating towards arachnoid villus mesothelium.

Adenosine Triphosphatases↗