IMMUNOLOCALIZATION OF TRANSFORMING GROWTH FACTOR-BETA-1 AND EPIDERMAL GROWTH-FACTOR RECEPTOR EPITOPES IN MOUSE INCISORS AND MOLARS WITH A DEMONSTRATION OF INVITRO PRODUCTION OF TRANSFORMING ACTIVITY

Day-14 lower incisors and day-18 first lower molars of mouse embryos produced in vitro transforming activities for non-confluent NRK cells co-cultured in agar, and mitogenic activities for exponentially growing NRK and BHK cells. The patterns of distribution of TGFβ1 and EGF receptor, both known to regulate cell proliferation, differentiation and transformation in vitro and suspected to play important roles in developmental processes, were studied during mouse odontogenesis by means of indirect immunofluorescence on fixed or frozen fixed sections. TGFβ1 epitopes were detected in the stellate reticulum of day-13 to day-16 incisors and of molars from day-17 onwards. Dental mesenchyme of day-14 incisors and postnatal molars, and peridental mesenchyme of bud and cap stage molars and incisors were also stained by TGFβ1 antibodies. EGF receptor was localized in the enamel organs of incisors and molars: the inner dental epithelium and later the outer dental epithelium rapidly became negative while the stellate reticulum remained stained. Incisor apical mesenchyme showed an intense reaction with EGF receptor antibodies after birth. © 1990.