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Biomedical subjects

A Hirashita

Publications and source records attributed to A Hirashita.

8 recordsLinked to original sources
PubMed1985

Phagocytosis of collagen by fibroblasts incident to experimental tooth movement.

The upper molars of adult Wistar rats were moved lingually by a wire spring for 5 and 9 days. Collagen-containing fibroblasts in the pressure zone caused by the tooth movement were investigated morphologically (forms characterized by type A and type B compartments) and cytochemically (location of acid and alkaline phosphatase activity). The following results were obtained: The distribution of collagen-containing fibroblasts with type A or type B compartments could not be distinguished clearly in either 5-day or 9-day specimens; Acid phosphatase activity was recognized in the Golgi apparatus, lysosomes, and elliptical bodies associated with type B compartments; Alkaline phosphatase activity was positive in the plasma membrane of collagen-containing profiles and in both intracellular and extracellular collagen fibrils. These results suggest that fibroblasts are capable of phagocytosing collagen fibrils in all areas of the cytoplasmic membrane and that digestion of collagen fibrils in fibroblasts may be associated with acid and alkaline phosphatase.

Acid Phosphatase↗
PubMed1976

The aspect of ultrastructural changes of the osteoblasts and surface areas of alveolar bone appearing in experimental tooth movement.

Molars of mature Wistar rats were moved experimentally by orthodontic elastic for four days. Then, the aspects of ultrastructural changes of the osteoblasts and structure of the alveolar bone surface which appeared in experimental tooth movement were studied. The following results were obtained. 1) These osteoblasts are classified into three groups according to their position. 2) The most active response to the orthodontic force is exhibited by the second group of cells with the ability of rapid production of abundant acid polysaccharide; i) Abundant rough surfaced endoplasmic reticulum with markedly dilated cisternae. ii) Well developed Golgi apparatus and electron opaque granules with a limiting membrane are found in the cytoplasm. Large granules are frequently seen to be secreted out of the cell. iii) The mitochondria are of large size and round shape with well developed cristae. 3) The surface of the new alveolar bone is covered with a belt-shaped structure consisting of small dense spherical-shaped structures. 4) Osteoclasts are rarely seen, but the original function of the cells appears to be almost inactive.

Alveolar Process↗