ビタミン A の過剰が歯胚の発育におよぼす影響に関する神経組織学的研究

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概要

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• The effect of hypervitamin A on the development of rat tooth germ was investigated in this study. Pregnant rats were treated with intraperitoneal injection of 100, 000 units or 150, 000 units of vitamin A on the 12th day of pregnancy. After macroscopic observation of rat embryos and young rats from 14 days of fetal life to 4 days after birth, a histological observation was made of the maxillary first molars. I. The general findings 1) In the macroscopic findings, the malformations in the vitamin A treated group were microstomia, micromelia, oligodactylia, etc. The degree of malformation was more intense in the group administered 150, 000 units than in the 100, 000 unit group. In the oral cavity, cleft palates were frequently observed and the degree of the defect was greater in the group administered 150, 000 units than in the 100, 000 unit group. 2) Hypervitamin A induced retardation of development and growth of dental anlage. The group administered 150, 000 units was more retarded than the 100, 000 unit group. 3) Hypervitamin A induced proliferation of blood vessels at the outer enamel epithelium and extreme hemorrhage at the enamel pulp of the developing enamel organ. Additionally, it induced retardations of the differentiation of the inner enamel epithelium and formation of the enamel matrix. Furthermore, it induced retardation of the differentiation of odontoblast and formation of dentin. 4) An increase in blood vessels by hypervitamin A was observed in the dental papilla. II. The neural findings 1) The innervation to the basement of the dental primordin was delayed by hyper-vitamin A. In addition, the nerve fibers were finer in comparison to those of the control groups and the nerve fiber bundles were diffusedly organized. 2) The small nerve fiber bundles which were observed in the mesenchymal tissues of the basement of the dental papilla were frequently seen in the areas near the epithelium diaphragm of the periphery of tooth germ, but they were scarce in the center of tooth germ. 3) In the control groups of 4-day-old rats, the fine nerve fibers entering the dental papilla were first seen in company with blood vessels. Conversely the nerve fibers entering the dental papilla were not recognized in the experimental groups.

• 九州歯科学会の論文
• 1986-02-25

著者

• 江 耀亭

  福岡歯科大学口腔病理学講座

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• ビタミン A の過剰が歯胚の発育におよぼす影響に関する神経組織学的研究
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