TRANSCRIPTION AND TRANSLATION OF CSF-1 IN THE DENTAL FOLLICLE

The dental follicle, a loose connective tissue sac which surrounds the unerupted tooth, is required for eruption to occur. Injection of colo ny-stimulating factor-1 (CSF-l)will accelerate molar eruption in rats, as well as stimulate tooth eruption in osteopetrotic rats. Utilizing in situ hybridization and reverse- transcription polymerase chain-reac tion techniques, we show here that CSF-1 mRNA is present in vivo in th e dental follicle of the first mandibular molar of the rat. Analysis o f the molars from day 0 through day 10 post-natally demonstrates that the maximal expression of CSF-1 mRNA is at day 3 post-natally. Immunos taining also reveals that the CSF-1 mRNA is translated, with immunosta ining for the CSF-1 itself, being heavy in early post-natal days and a bsent by day 9 postnatally. In view of the fact that there is a maxima l influx of mononuclear cells (monocytes) into the dental follicle at day 3 post-natally-an influx which increases the numbers of osteoclast s needed to form a tooth eruption pathway-it is probable that the maxi mal expression of CSF-1 mRNA by day 3 post-natally contributes to this monocyte influx. Thus, this study establishes a relationship among a molecule (CSF-1), cell (monocyte), and tissue (dental follicle) that a ppear to play a major role in tooth eruption.