トノサマ蛙の下顎発育時における下唇軟骨とメッケル軟骨との関係ならびに下顎骨の骨化について
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概要
- 論文の詳細を見る
Growth phases of Meckel's cartilage and subsequent appearance and development of the mandible were studied with reference to the patterns of ossification using frogs as materias- 1. Appearance and Disappearance of Meckel's Cartilage The lower lip cartilage and Meckel's cartilage made their appearance as respective anlage when the head-tail length of frog reached 8-mm. At about the time when the length was 38-mm, both organs showed hyaline ossification and at the same time lost clearness of boundary separating them. At 42-mm stage of the animal a part of the lower lip cartilage disappeared, but the remaining part continued to grow and took a horizontal posi. tion. Meckel's cartilage, on the other hand, extended itself toward outer-posterior direction in company with the backward turn of palatoquadratum, and the tapering end of the cartilage became fused with the rear end of the lower lip cartilage. When the frog lost its tail and the body was 20-mm long, the cartilage had completed its general shape with cylindrical, slender U-curve. Although the cartilage continued to elongate and expand thereafter, the foremost part became almost lost in the adulthood of the frog and even the posterior part showed the trend of degeneration. 2. Generation and Development of Mandible At 42-mm stage of head-tail length, there started the formation of mentale in the region where the lower lip cartilage and Meckel's cartilage were fused. At 40-mm stage of body length when the frog started losing its tail, anlages of both dentale and angulare made their appearance and these organs showed ossification with progressive development and body enlargement. With 20-mm stage of body length, vigorous growth of mentale, dentale and angulare was taking place around Meckel's cartilage as central axis of the mandible, the first near the tapering end, the second in the posterior lateral side and the third in the posterior inner side, and at this stage the tapering end of dentale was already fused with mentale by means of its outer posterior branch. With 45-mm stage of body length, ossification of respective bone proceeded further and altogether gave an approximate appearance of adulthood mandible. The mandible of frog, therefore, is constituted from the bony components of mentale, dentale and angulare. 3. Pattern of Ossification Dentale and angulare are formed by the desmoid ossification, while mentale is completed by the metaplastic ossification where Meckel's cartilage is directly converted into bone tissue.
- 九州歯科学会の論文
- 1972-11-30