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KMID : 0355820210420010143
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Korean Journal of Oral Anatomy
2021 Volume.42 No. 1 p.143 ~ p.153
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Morphological study on the cementum in the tooth of Xenopus laevis
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Park Byung-Keon
Lee Young-Hoon
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Abstract
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Teeth are supported by the periodontium, which is composed of cementum, periodontal ligaments, and alveolar bone. The cementum consists of acellular and cellular cementum according to the histological features. The functional tooth of Xenopus laevis is shed and formed repeatedly during its lifetime, which is called polyphyodont. Xenopus laevis has various stages of tooth germ or tooth, i.e., lamina, cap and bell stages, and functional tooth. The cementum is also resorbed and formed, reiteratedly. However, little is known about the morphological data on the cementum in the teeth of Xenopus laevis. Juvenile and adult frogs were collected at the age of three month and three years or older. Upper jaws were fixed in a 4% paraformaldehyde solution at 4℃ overnight. The samples were treated with 10% EDTA and 1x PBS solution for decalcification and then embedded with paraffin via dehydration with graded ethanol and cleared using xylene. Five μm tissue sections were stained with hematoxylin-eosin (HE), picrosirius red (PR), Masson’s trichrome (MT) staining, and IBSP in situ hybridization. Hertwig’s epithelial root sheath (HERS) was continuous without fragments and covered with root dentin. A functional tooth was attached to the (pre)maxilla. The distribution of collagen fibers is shown in 1) a layer between HERS and tooth, and 2) the ankylosis area of the apical portion of the root lacking HERS. IBSP is only expressed in the latter. We suggest that the cellular cementum might be formed in the ankylosis area of the apical portion of the tooth root by the localization of collagen fibers and IBSP RNA in Xenopus laevis. Therefore, these results could be useful for molecular genetics and ultrastructural research of the cementum in the teeth of Xenopus laevis.
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KEYWORD
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Xenopus laevis, tooth, cementum, morphological study, IBSP
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