Biomaterial Database

TEM observations on the ameloblast/enamel interface in the rat incisor. 2002

S Risnes, and D Septier, and D Deville de Periere, and M Goldberg

Department of Oral Biology, Faculty of Dentistry, University of Oslo, PO Box 1052, Blindern, 0316 Oslo, Norway. steinar_risnes@hotmail.com

The structure of rat incisor enamel is established at the topographically complex interface between secretory ameloblasts and forming enamel. The aim of this study was to gain additional information on this interface by sectioning parallel with the rows and the long axis of Tomes' processes and prisms. Rats were sacrificed and fixed by glutaraldehyde/paraformaldehyde perfusion. After dissection, demineralization and embedding transverse jaw/incisor segments were cut, reembedded, and reoriented. Sections were prepared for and observed in the transmission electron microscopy (TEM). The intraenamel part of Tomes' process was about 18 microns long. The forming prism occupied a longitudinally grooved invagination on its apical aspect. The parts of Tomes' process forming the side walls of the groove were attenuated and showed variation in extent and outline. Prism growth occurred over the whole grooved area. An estimation of Tomes' process secretory area in rat compared with data from humans suggests that there may be a relationship between secretory area and rate of prism formation. Prism crystals were oriented obliquely or parallel to the secretory surface of Tomes' process. At interprism growth sites matrix deposition was irregular and required some redistribution to conform to the pattern of interprism sheets.

UI	MeSH Term	Description	Entries
D007180	Incisor	Any of the eight frontal teeth (four maxillary and four mandibular) having a sharp incisal edge for cutting food and a single root, which occurs in man both as a deciduous and a permanent tooth. (Jablonski, Dictionary of Dentistry, 1992, p820)	Incisors
D008297	Male		Males
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D003743	Dental Enamel	A hard thin translucent layer of calcified substance which envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. Under the microscope, it is composed of thin rods (enamel prisms) held together by cementing substance, and surrounded by an enamel sheath. (From Jablonski, Dictionary of Dentistry, 1992, p286)	Enamel,Enamel Cuticle,Dental Enamels,Enamel, Dental,Enamels, Dental,Cuticle, Enamel,Cuticles, Enamel,Enamel Cuticles,Enamels
D000565	Ameloblasts	Cylindrical epithelial cells in the innermost layer of the ENAMEL ORGAN. Their functions include contribution to the development of the dentinoenamel junction by the deposition of a layer of the matrix, thus producing the foundation for the prisms (the structural units of the DENTAL ENAMEL), and production of the matrix for the enamel prisms and interprismatic substance. (From Jablonski's Dictionary of Dentistry, 1992)	Ameloblast
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar Rats
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus