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Updated: Sep 29, 2026

Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants
Published on: March 29, 2018
Odontoblasts enhance the maturation of enamel crystals by secreting EMSP1 at the enamel-dentin junction
1Department of Biochemistry, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan. fukae-m@tsurumi-u.ac.jp
Abstract:
The temporal expression patterns and activity distributions of enamelysin and EMSP1, which are the major proteinases in immature enamel, were characterized. Extracellular matrix fractions from developing porcine incisors, individually comprised of predentin, dentin, and four secretory-stage enamel samples, including the highly mineralized enamel (HME) at the enamel-dentin junction (EDJ), were isolated, and their resident proteinases were identified by zymography. Soft-tissue fractions, which included cells from the extension site of enamel formation (ESEF), secretory- and maturation-stage ameloblasts, and odontoblasts, were characterized histologically and by RT-PCR for their expression of enamelysin and EMSP1. A significant finding was that EMSP1, expressed by odontoblasts, concentrates in the HME, but is not detected in predentin or dentin. We conclude that odontoblasts deposit EMSP1 via their cell processes into the deepest enamel layer, which facilitates the hardening of this layer and contributes significantly to the functional properties of the EDJ.
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