Figure 4. Histological analysis (H&E) of incisors and distal femurs from 18-day-old control and Dmp1 null embryos. (A) Representative tooth germs (upper incisors) of the wild-type (+/+, left) and the homozygous null (-/-, right) embryos of day 18 are shown. There are no apparent morphological changes in dentin (red) and odontoblast and ameloblast layers (purple). (B) Representative long bone (femur) of the wild-type (+/+, left) and the homozygous null (-/-, right) embryos of day 18 are shown. A slightly expanded hypertrophic zone and a widened bone shaft are shown. Am, ameloblast; HC, hypertrophic chondrocytes; Od, odontoblasts; d, dentin.