title: Inner enamel epithelia synthesize and secrete enamel proteins during mouse molar occlusal "enamel-free area" development.
abstract: Mesenchyme-derived instructions for odontogenic epithelial differentiation into ameloblasts and the production of enamel matrix has been well established. However, it is not known how position-specific differences within the enamel organ of rodent molar tooth organs regulate the enamel-forming vs. the enamel free areas in the developing cusp. Light microscopy, transmission electron microscopy, and immunocytochemistry using a rabbit anti-mouse amelogenin antibody, were used to map the position-specific patterns within the enamel organ. In the enamel-forming area, ameloblasts were associated with stratum intermedium. In the enamel-free area, another cell type was interposed between inner enamel epithelia (IEE) and stratum intermedium. IEE in the enamel-free area did not have Tomes' processes and secreted enamel matrix not only toward dentin but also between IEE cells. IEE became confluent with stellate reticulum; at this position stratum intermedium cells were no longer detected. The thickness and orientation of dentin matrix collagen fibers in the enamel-free area were different from the fibers in the enamel-forming area. These results suggest that the patterns of epithelial cell-cell and cell-matrix associations during position-specific enamel organ epithelial differentiation may regulate ameloblast matrix synthesis and/or the matrix secretion pathway.
authors.affiliation: 2nd Department of Oral Anatomy, School of Dentistry, Tohoku University, Sendai, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: P
authors.initials: P
authors.lastname: Bringas
authors.forename: H C
authors.initials: HC
authors.lastname: Slavkin
mesh_terms: D000818:Animals; D002450:Cell Communication; D002454:Cell Differentiation; D003743:Dental Enamel / Q000378:metabolism* / Q000648:ultrastructure; D004658:Enamel Organ / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D008854:Microscopy, Electron; D008963:Molar / Q000196:embryology / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure