EPIDERMAL GROWTH-FACTOR AND EPIDERMAL GROWTH FACTOR-RECEPTOR EXPRESSION IN THE MOUSE DENTAL FOLLICLE DURING TOOTH ERUPTION

When the role of exogenous epidermal growth factor (EGF) during tooth eruption was first demonstrated it was strongly suggested that EGF was a natural regulator of eruption. Recent immunohistochemical studies h ave shown that EGF and EGF-receptors are localized in the dental folli cle, alveolar bone and ameloblasts before and during the prefunctional stage of eruption. Localization of mRNA for EGF has also been success fully attempted in mouse incisors and molars. The purpose now was to s tudy the temporal expression of EGF and EGF receptor genes in the coro nal aspect of the dental follicle. First molars from 2-, 5-, 9- and 11 -day-old CD-1 mouse neonates were incubated in 1% trypsin for 1.5 h at 4 degrees C. Follicles were carefully separated from the coronal aspe ct of the molar and processed for RNA extraction. Reverse transcriptas e-polymerase chain reaction was performed on each mRNA sample. EGF exp ression was detected at day 2, 5 and 9 in the coronal aspect of the fo llicle whereas EGF-receptor expression was found at day 9 only. These findings strongly suggest that cells of the dental follicle are the ta rget of EGF at a specific stage of their development and therefore may have a very Important role during eruption. Copyright (C) 1996 Elsevi er Science Ltd.