LOCALIZATION OF PRO-COLLAGEN TYPE-II MESSENGER-RNA AND COLLAGEN TYPE-II IN THE HEALING TOOTH SOCKET OF THE RAT

Sprague-Dawley rats (50 days old) were anaesthetized and the maxillary right molars extracted. The rats were killed at 2, 3, 6, 8 and 10 day s after extraction. The maxillae were dissected and prepared for eithe r routine histology, ill situ hybridization for pro-collagen type II m RNA, or immunohistochemical detection of collagen type II. Pro-collage n type II mRNA was expressed maximally in the healing tooth socket al 8 days after the extractions, but the protein was not expressed at any time. This suggests that the translation of pro-collagen type II mRNA does not occur in osteoblasts following tooth extraction. Ossificatio n was present in the socket at 6 days after the extractions, which is consistent with the suggestion that an early feature of osteoblastic d ifferentiation may be the expression of type II pro-collagen mRNA.