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Figure 3. NOS immunoreactivity in the distal side of the disto-palatal root of the maxillary first molar. Endothelial NOS immunostaining sections in normal, hypofunction, and recovery groups (A,B,C). (A) Blood vessels in PDL were observed clearly in general. Endothelial NOS was noted only in blood vessels. (B) The diameters of periodontal blood vessels appeared to be smaller, and the number of eNOS-immunopositive cells decreased. (C) The recovered periodontal blood vessels increased in diameter and number compared with the hypofunction group. In addition, the number of eNOS-immunopositive cells increased close to that of the normal periodontal group. Mononuclear phagocyte lineages were observed at the border of the PDL and alveolar bone.
Inducible NOS immunostaining sections in normal, hypofunction, and recovery groups (D,E,F). (D) Inducible NOS-immunopositive cells were observed in vascular smooth-muscle cells, fibroblasts, and mononuclear phagocyte lineage. (E) The PDL displayed a decrease in thickness and disorientation of PDL fibers. The diameters of periodontal blood vessels appeared to be smaller, and the number of iNOS-immunopositive cells decreased. (F) Vascular smooth-muscle cells and fibroblasts recovered to close-to-normal levels. Mononuclear phagocyte lineage was observed at the border of the PDL and alveolar bone, especially in the rugged profile area. 
, blood vessel; 
, fibroblast; 
, mononuclear phagocyte lineage. Bar: 100 µm.
