Abstract
We investigated the histochemical localisation of versican, aggrecan and hyaluronan in the developing condylar cartilage of the fetal rat mandible at d 15-17 of gestation. At d 15 of gestation, immunostaining for versican was detected in the anlage of the future condylar process (condylar anlage), although the staining intensity showed a considerable regional variation. At d 16 of gestation, a metachromatically stained matrix firstly appeared in the condylar anlage. Aggrecan, hyaluronan and versican were simultaneously detected in this newly formed condylar cartilage. At d 17 of gestation, immunostaining for versican became restricted to the perichondrium and was barely detected in the cartilage. Colocalisation of versican and aggrecan was also seen in the cranial base cartilage at d 14 of gestation. These results indicate that although versican is replaced by aggrecan during the transition from prechondrogenic tissue to cartilage, both molecules were temporally colocalised in the newly formed cartilage. A hyaluronan-rich, low-versican area was identified in the posterior end of the condylar anlage during d 15-17 of gestation. The existence of this area is a unique structural feature of the developing condylar cartilage.