AMELOBLAST-LINEAGE CELLS OF RAT TOOTH GERMS PROLIFERATE AND SCATTER IN RESPONSE TO HEPATOCYTE GROWTH-FACTOR IN CULTURE

Hepatocyte growth factor (HGF) is considered to be one of the mediator s of epithelial-mesenchymal interactions during early organogenesis an d to be involved in the development of murine molars. In this study, t he immunohistochemical localization of HGF and of its receptor, c-Met, revealed that HGF was distributed in the proliferating mesenchymal ce lls in the dental papillae and that c-Met was continuously expressed i n the epithelial cells during the development of rat incisors. These o bservations confirmed the involvement of HGF in the development of rat incisors, as demonstrated previously in molars. We then used a primar y culture of ameloblast-lineage cells, prepared from mandibular inciso rs of young rats, to examine the direct effects of HGF on the growth a nd differentiation of ameloblasts. We found that HGF at 2-20 ng/ml ind uced a marked increase in the number of ameloblast-lineage cells and i n the scattering of such cells. Our results suggest that HGF promotes the proliferation and scattering of ameloblast-lineage cells simultane ously.