Phenotype Image Detail

Image

Caption

Demineralized sections of wild type (+/+, A-C), Mmp20^tm1Jdb/Mmp20⁺ (+/-, D-F) and Mmp20^tm1Jdb/Mmp20^tm1Jdb (-/-, G-I) mice showing ameloblasts (Am), enamel space (En), and dentin (De). The wild type and heterozygous sections show tall secretory-stage (A and D) ameloblasts with Tome's processes penetrating into stained proteins of the enamel layer. The secretory-stage ameloblasts from homozygous mice (G) show ameloblasts that do not have a discernible Tome's process within the enamel protein layer. In the early maturation stage (B, E and H) ameloblast length was reduced for all incisors examined. For the wild type and heterozygous mice (B and E), the matrix was sparse and lightly stained, indicating an increase in mineralization and the loss of protein. In contrast, the enamel matrix protein from the homozygous mouse (H) persisted. In the late maturation stage the enamel matrix of wild type (C) and heterozygous (F) mice was mostly removed. Conversely, enamel matrix in homozygous mice persisted, an abnormally thick layer of protein separated the ameloblasts from the enamel surface (I), and nodule-like formations surrounded by ameloblasts were observed (I, arrows).

Copyright

This image is from Caterina JJ, J Biol Chem 2002 Dec 20;277(51):49598-604 and is displayed with the permission of the American Society for Biochemistry and Molecular Biology who owns the Copyright. Full text from JBC. J:80925

Associated Alleles

Symbol	Name
Mmp20^tm1Jdb	matrix metallopeptidase 20 (enamelysin); targeted mutation 1, John D Bartlett

Associated Genotypes

Allelic Composition	Genetic Background
Mmp20^tm1Jdb/Mmp20^tm1Jdb	involves: 129P2/OlaHsd * C57BL/6