Phenotype Image Detail

Image

Caption

Transmission and scanning electron microscopic images of enamel architecture changes by redesign of amelogenin in mouse incisor teeth. Images in panels A reflect the enamel organization from an Amelx^tm1Msnd/Amelx^tm1Msnd (deltaA/deltaA) mouse, panels B reflect the enamel from an age matched wild type mouse (Wt/Wt), and panels C reflect the enamel from a Amelx^tm2Msnd/Amelx^tm2Msnd (deltaB/deltaB) mouse. The images shown in panels 1 are transmission electron microscopy projections from an area adjacent to the secretory end of the ameloblasts and reveal newly synthesized enamel matrix proteins and crystallites. The loss of nanospheres and increased numbers of shortened crystallites is identified in Amelx^tm1Msnd/Amelx^tm1Msnd, and a collapse of nanospheres with disruption of crystallites is seen in Amelx^tm2Msnd/Amelx^tm2Msnd compared with wild type enamel. The images shown in panels 2 and 3 are scanning electron micrograph (SEM) projections at two magnifications of cross-sections of incisors obtained by fracture at similar areas of enamel maturation. The enamel is thinned, the rod-interrod demarcations are disrupted and the weaving among the enamel rods is absent in both mutants compared with wild type. The dotted line identifies the dentine enamel junction. The images shown in panels 4 and 5 are SEM projections at two magnifications of the newly formed enamel surface after the removal of the ameloblast cells. Disruption to the shape and size of the secretory end piece of ameloblasts, known as Tome's processes, are observed. For the enamel made from Amelx^tm1Msnd/Amelx^tm1Msnd amelogenin, the secretory end pieces are squat and enlarged. In the enamel made from Amelx^tm2Msnd/Amelx^tm2Msnd amelogenin, the secretory end pieces are more numerous but smaller. These changes to Tomes' processes are reflected in the rod organization shown in SEM images from fractured enamel in panels 2 and 3.

Copyright

This image is from Zhu D, J Biol Chem 2006 Jul 28;281(30):21173-82 and is displayed with the permission of the American Society for Biochemistry and Molecular Biology who owns the Copyright. Full text from JBC. J:116448

Associated Alleles

Symbol	Name
Amelx^tm1Msnd	amelogenin, X-linked; targeted mutation 1, Malcolm L Snead
Amelx^tm2Msnd	amelogenin, X-linked; targeted mutation 2, Malcolm L Snead

Associated Genotypes

Allelic Composition	Genetic Background
Amelx^tm1Msnd/Amelx^tm1Msnd	involves: 129X1/SvJ
Amelx^tm2Msnd/Amelx^tm2Msnd	involves: 129X1/SvJ