Natriuretic peptides (NPs), guanylin, uroguanylin, heat-stable enterotoxin type a (STa), and the cystic fibrosis transmembrane conductance regulator (CFTR) are important regulators involving water and ionic balance in vertebrates. The present report points out the evolution of osmoregulatory systems and their effector organs, including the rectal glands of eels, frogs, and sharks; the salt glands of birds; and the salivary glands of mammals, including those of humans. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and the activity of their respective receptors in the organs of vertebrates were reported as biological characteristics of heart hormone. This review focuses on Cl^-/HCO₃^- exchange activity in the salivary gland ducts and ductal basal cells that express NPs and related regulators. This report describes published histochemical findings on protein and mRNA expression in ductal basal cells and the biological significances of those findings with regard to the mammalian salivary gland duct system and a number of growth factors synthesized in the granular convoluted tubules (GCT).

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The purpose of this study was to evaluate the morphological and molecular effects of atelocollagen sponges placed in rat tooth extraction sockets in their early stages of wound healing. Right incisors of rats were extracted, and atelocollagen sponges were placed into the tooth extraction sockets. Sockets without atelocollagen served as controls. Extraction socket tissues were histologically evaluated for 3 weeks after surgery, and mRNA expression levels for type I collagen and osteocalcin were also quantified. At the time that non-specific fibrous connective tissue invaded the alveolar bone ridge area of the sockets from the outside in the control group, new bone formation was seen up to the level of the alveolar bone ridge in the experimental group. There was a significantly higher expression level for type I collagen mRNA in the experimental group, whereas there was no significant difference in the expression of osteocalcin mRNA between the two groups. These results suggest that atelocollagen plays a role in maintaining space by stimulating collagen production but does not accelerate cell proliferation or osteoinduction.

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Background: Oral submucous fibrosis (OSF) is a premalignant fibrotic oral disease. The aim of this study was to investigate the relationship between fibrosis and the expression of TGF-β1, MMP-1, and TIMP-1 and epithelial dysplasia in OSF. Methods: Forty-two tissue samples from the oral mucosa of OSF patients were histopathologically and immunohistochemically examined. The expressions of TGF-β1, TIMP-1, MMP-1 and PCNA were observed using immunohistochemistry. Results: Compared to normal oral mucosa (NOM), MMP-1 expression was attenuated in OSF while TGF-β1 expression was upregulated (P<0.05). TIMP-1 expression of OSF was slightly elevated or similar to NOM. Proliferating activity was correspondingly increased in dysplastic OSF and was found to be statistically significant (P<0.05). No significant relationship was found between epithelial dysplasia and expressions of TGF-β1, MMP-1, and TIMP-1 in OSF. Furthermore, the relationship between epithelial dysplasia and the degree of fibrosis failed to show any positive correlation in OSF. Conclusions: This study provides further evidence that the fibrotic process in OSF is not only due to excessive collagen deposition but also due to disequilibrium in the ECM remodeling process. Neither the ECM remodeling process nor tissue fibrosis of OSF directly shows any significant effect on epithelial dysplasia.

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We report a rare case of central Schwannoma, a type of nerve sheath tumor, arising in the mandibular bone of a 34-year-old man. A periapical lesion was discovered during routine dental treatment. Radiographically, the lesion was a large round-shaped and well-defined radiolucent lesion with a radiopaque rim in the anterior apical region, which extended from the right canine to the left lateral incisor in the mandible. The surgically removed mass was a relatively well-encapsulated tumor, measuring 1.5 cm in diameter. Histologically, the tumor showed a typical histology of Antoni type A of Schwannoma, focally interspersed with myxoid areas in which tumor cells had nuclear atypia. A review of the literature revealed that there have been only a total of 54 reported cases of central Schwannoma of the jaw bones including the present case, most of which were located in the posterior part of the mandible with a female/male ratio of 1.6 to 1 and a mean age of 33.9 years.

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A case of focal osteoporotic bone marrow defects (FOBMDs) with a simple bone cyst-like change arising in the bilateral anterior maxilla of a 9-year-old Japanese boy is reported. Two FOBMD lesions were simultaneously found by chance as small oval-shaped unilocular radiolucencies symmetrically located between the canines and lateral incisors on a panorama radiograph during dental treatment of the patient's right maxillary canine, which erupted obliquely as the canine tooth roots were laterally displaced by the lesions. The lesions were surgically extirpated under a clinical diagnosis of developmental jaw cysts. However, they were shown at surgery not to be cysts but instead bone-marrow-like tissues, though the right lesion contained a cavity space within it. Histopathologically, they were fatty marrow without hematopoiesis, and irregularly-shaped bony trabeculae and blood clots were seen scattered throughout the marrow. They were diagnosed as FOBMD (left) or FOBMD with simple bone cyst (right), although they did not contain hematopoietic marrows. Thus, their fully fatty change with some blood pools suggests that they were in the initial stage of developing into simple bone cysts. Based on these histological observations, we propose a new hypothesis of FOBMD as one of the histopathogenetic precursors of simple bone cyst.

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