Quantitative image analysis of hyaluronan expression in human tooth germs

The expression of hyaluronan in human tooth germs was studied by using a bi otinylated hyaluronan-binding complex and quantitative digital image analys is. At the cap stage, dental papilla exhibited a moderate staining, while i ntense reaction was observed in the apical portion of presecretory amelobla sts, stellate reticulum, and in dental basement membrane. When the enamel a nd dentine matrices started to develop, a strong hyaluronan reaction was ev ident in the young enamel and the apical portion of secretory ameloblasts. No hyaluronan could be detected in the secretory ameloblasts and enamel mat rix of the early (9-wk-old) post-natal stage. It is concluded that hyaluron an may play a transitory role in the early phase of the development of the enamel matrix organization. A very weak signal was observed in the wall of dentin tubules, whereas the rest of the dentine matrix was not stained. The odontoblasts and the pulp were also moderately stained, and these reaction s gradually decreased with age, suggesting that hyaluronan may also contrib ute to the development of dentine matrix and pulp.