メダカ咽頭歯・咽頭骨にみられる硬組織間接着界面の形態学的特徴

medaka

北海道歯学会

北海道歯学雑誌

The adhesion interface between hard tissues in cement lines of bone in mammals shows a positive reaction in periodic acid-SCIFF （PAS） staining. In addition, bone sialoprotein （BSP）, osteopontin （OPN）, and glycosaminoglycans （GAGs） can be detected. It has been reported that such noncollagenous proteins participate in adhesion between hard tissues. Bone tissue phylogenically appears in Teleost fish. Therefore, it is important to understand the characteristics of the adhesion interface between hard tissues in Teleost fish when this significance in mammals is considered. The present study aims to observe the adhesion interface between hard tissues, tooth-pedicel-interface （TPI） in upper pharyngeal bone of Japanese medaka, and to clarify the morphological characteristics. The upper pharyngeal bone and teeth of Japanese medaka was used in this study. For light microscopic （LM） observation specimens were embedded in paraffin or resin （LR-white） after fixation, decalcification and dehydration. Frontal directional slices were made, stained with haematoxylin-eosin （HE）, PAS, AZAN, and observed by LM. For transmission electron microscopic （TEM） observation, specimens were embedded in LR-white resin. Ultra thin frontal directional sections were made and were observed by TEM. By LM, TPI was observed as a line-shaped structure without staining of HE and PAS. However, there were collagen fibers with AZAN straining. Cement lines were not strained with HE, PAS or AZAN, and they were observed as lines with irregular contours. By TEM, collagen fibers were observed in TPI and there were some fibers connected to those in the matrix of tooth and pedicel. On cement lines there was no structure and only exposed collagen fiber was observed on the surfaces of bone. These findings suggest that TPI have no PAS-positive materials and are made of collagen fibers. The cement lines are made of only minerals without any collagen fiber or PAS-positive materials.