ラット胎生期歯胚の発達に伴う三次元的観察

概要

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Using Wistar rats from 14 to 20 days gestation, we observed the three dimensional growth rates of the mandibular incisor and molar teeth, through the measurement by microphotographs and wax reconstruction of the serial sections of the tooth germs. In the incisor tooth germs, the enamel organ showed the bud-stage at 15 and the bell-stage at 16 days of fetal life. The crescentic enamel organ presented at 17 days gestation. There was a remarkable swelling toward the lingual side, and the whole tooth germ began to bend at 18 days fetus. At 19 days gestation, the deposition of the predentin was recognized in the tip of the incisor edge. In the 20 days fetus, the pulp cells around the tip of dentin formed the so-called osteodentin. At this stage the incisor was represented by a very elongated tooth germ which extends farther back on the labial than on the lingual side. On the other hand, only the tooth germs of the first and second molars were visible in the rat fetal life. The first appearance of the tooth bud was at 15 and 17 days gestation in the first and second molars, respectively. In these molars, the tooth germ primarily grew farther downward on the medial than on the lateral margin. By the 19th day of gestation, all of the positions of cusp were suggested in the first molar tooth germ, although no cusp of the second molar developed until the 20th day in utero.
鹿児島大学の論文
1987-03-26