PubMed Health⌕ Search

Biomedical subjects

N Piret

Publications and source records attributed to N Piret.

5 recordsLinked to original sources
PubMed1976

Bone in dermatosparaxis. I. Morphologic analysis.

Normal (N-) calf bone consists of lamellae regularly spaced and oriented parallel to the periosteum. The lamellae increase in thickness from the periosteum to the medullary cavity, by apposition of layers of cells and a calcifying matrix on either side of a hypercalcified primer. In the dermatosparactic (D-) bone, the hypercalcified primer is barely visible and the cells are irregularly arranged within the lamellae. The poorly defined vascular spaces are partly filled with an acellular calcified material. In the D-bone, the collagen fibers are sparse and radiate from the vascular space, while in the N-bone they are abundant and laid down concentric with the blood channels. In the D-bone, only a few weeks old, the outer lamellae are radially oriented with respect to the medullar cavity, while haversian remodeling already occurs in the inner part of the diaphysis. At 6 months, the inner half of the diaphysis is made up of normal haversian secondary bone, while the outer half is made up of radial lamellae. The alteration of the mechanical properties of procollagen fibers in the D-bone might be responsible for its defective organization. A resistant fibrous framework, therefore, seems required to ensure the spatial organization of the cells in the calcifying matrix and to maintain its cohesion.

Age Factors↗
PubMed1976

Tetracyclines, doxycycline and calcified tissues.

The use of radioactive isotope techniques has led to a thorough re-assessment of our knowledge of bone histology. It is known that tetracyclines faithfully follow the pattern of calcium metabolism in the body. Fluorescence microscopy, after double labeling with tetracyclines and alizarin red S, is very useful for collection of qualitative and quantitative data on compact and spongy bone remodeling. Two illustrations are presented which demonstrate how oxytetracycline and doxycycline administered in therapeutic doses to growing dogs, become deposited in the dentine. The significance of these findings is discussed.

Animals↗
PubMed1975

[Notes on osteoclastic resorption].

Microradiography of transverse sections in diaphyseal compact bone of old dogs shows many osteons with irregularly delimited haversian canals, very similar to a resorption cavity (fig. 1). Microradiography of longitudinal sections in the same material reveals that the enlargement of the canal affects only a fraction of its length (fig. 2). After methylene blue staining, no osteoclasts have been observed but only small mononucleated cells (fig. 3 and 4). The signification of these observations is discussed.

Animals↗
PubMed1975

[Morphometric study of the dog radial diaphysis].

Cross sections in the midshaft of the radius bone from various dogs show an important polymorphism (fig. 1). However, calculation indicates that all these sections are comparable and of elliptical surface (fig. 2). The mean thickness of the cortex increases with total area (fig. 3) but is independant of the age of the animals (fig. 4).

Age Factors↗