Thesis or Dissertation 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

松村, 馨

 哺乳類における骨接合線やセメント象牙境などの硬組織間接着界面は脱灰標本で過酸化ヨウ素シッフ反応(periodic acid-SCIFF)(PAS)陽性反応を示し, bone sialoprotein, osteopontin, glycosaminoglycansが局在し, これら非膠原性タンパクは硬組織間の接着に関与すると報告されている. 骨組織は系統発生学的に硬骨魚類よりみられることから, その骨接合線の構造を理解することは哺乳類におけるその意義を理解する上で重要である. しかしながら, その報告はない. 硬骨魚類の歯は骨性結合あるいは歯足骨を介在して骨と線維性結合しているが, そこでの非膠原性タンパクの存在は不明である. 本研究はメダカ咽頭骨にみられる骨接合線と咽頭歯・歯足骨界面の構造を明らかにするものである. 試料としてメダカ咽頭歯・咽頭骨を用いた. 試料は固定, 脱灰, パラフィン・樹脂(LR-white)包埋後, 前頭方向から切片を作製しHE・PAS・AZAN染色を行い光学顕微鏡で観察した. 透過型電子顕微鏡観察には試料を固定, 脱灰, LR-white包埋し, 前頭方向から超薄切片を作製し, 透過型電子顕微鏡で観察した. 光学顕微鏡では上咽頭歯・歯足骨界面はHE・PAS染色に染まらない線状構造を示し, AZAN染色では膠原線維が観察された. 下咽頭歯では上咽頭歯で見られたような歯・歯足骨界面は観察されなかった.骨接合線はHE・PAS・AZAN染色のいずれの染色にも染まらない線状構造として観察された. 透過型電子顕微鏡による観察では, 上咽頭歯・歯足骨界面には横紋構造をもつ膠原線維が存在し, これら線維の幾つかは歯と歯足骨を構成している基質線維と連続していた. 骨接合線は無構造領域として観察され, この領域が骨に面する部には露出した膠原線維が観察された. 以上の結果から, メダカの硬組織間接着界面である上咽頭歯・歯足骨界面と骨接合線はPAS陽性物質を含まず, 上咽頭歯・歯足骨界面は膠原線維から, 骨接合線は無機質から構成されていることが示唆された.
Adhesion interface between hard tissues like cement lines of bone in mammals shows positive reaction of periodic acid-SCIFF (PAS) staining, and bone sialoprotein (BSP), osteopontin (OPN), and glycosaminoglycans (GAGs) are also detected there. 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 characteristisc of adhesion interface between hard tissues in Teleost fish when the significance of that in mammals is considered. The present study aims to observe adhesion interface between hard tissues, tooth-pedicel-interface(TPI) in upper pharyngeal bone of Japanese medaka, and to clarify the morphological characteristics of them. Upper pharyngeal bone and tooth of Japanese medaka were used in this study. For light microscopic (LM) observation, specimens were embedded in paraffin or resin (LR-white) after fixation, decalcification and dehydration. Slices were made in frontal direction, stained with haematoxylin-eosin(HE), PAS, AZAN, and observed by LM. For transmission electron microscopic (TEM) observation, specimens were embedded in LR-white resin. Ultrathin sections were made in frontal direction and were observed by TEM. By LM, TPI were observed as 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 and 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 and and that cement lines are made of only mineral without any collagen fiber and PAS-positive materials.
Hokkaido University(北海道大学). 博士(歯学)

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