Methods: ICR mice E 14.0 to 18.0 were used in this study. Heads and lower limbs were immersed in 4% paraformaldehyde and routinely embedded in paraffin. Sections were cut longitudinally to the l mandibular condylar process. Immunohistochemical localization of MEPE was detected by streptoavidin-biotin methods.
Results: At E14.0, the Meckel’s cartilage was clearly formed and anlage of condylar cartilage was recognized as a mesenchymal cell condensation. Immunostaining for MEPE was strongly detected in whole Meckel’s cartilage, but not in the condylar anlage. The condylar cartilage was first detected and at E 15.0 and immunostaining for MEPE was detected in the newly formed condylar cartilage. At E 16.0, cartilage extended in length, and MEPE immunostaining was detected in the flattened cell layer to whole hypertrophic cell layer, but not in the fibrous cell layer at the surface. Some of lacunae in the mandibular bone showed immunostaining for MEPE, but there were pretty amount of lacunae not showing immunostaining.
Conclusions: These results indicate that MEPE should be evaluated as a kind of extracellular matrix in cartilage.