Retinoic Acid Signal Negatively Regulates Osteo/Odontogenic Differentiation of Dental Pulp Stem Cells

Figure 1

Morphological changes and mRNA expression changes of RARβ and CRABP2 in the DP during crown calcification of DC of miniature pig. (A, A) In HE staining of DC on E50, tooth germ develops into bell stage; (A) exhibits the enlarged image of the boxed region in (A). The enamel organ (EO) forms and surrounds the dental papilla (DP) which is located next to the inner enamel epithelium (IEE). (B, B) In HE staining of DC on E60, tooth germ develops into calcification stage; (B) exhibits the enlarged image of the boxed region in (B). The elongated odontoblasts (O) appear at the frontier of the DP. The predentin (PD) and enamel are secreted between the DP and EO. The outer enamel epithelium (OEE) and stellate reticulum (SR) can be identified on E50 and E60. The expression patterns of RARβ and CRABP2 in DP are studied by in situ hybridization (ISH); the boxed regions in (C–F) are enlarged in (C–F). Expression levels of RARβ and CRABP2 are largely decreased in DP from E50 to E60. Scale bars represent 200 μm (A–F) and 50 μm (A–F).