IMMUNOCYTOCHEMICAL DEMONSTRATION OF NERVE GROWTH-FACTOR RECEPTOR (NGF-R) IN DEVELOPING HUMAN FETAL TEETH

Evidence is accumulating that nerve growth factor receptor (NGF-R or p 75(NGFR)) can mediate cell growth and differentiation of non-neuronal cells. NGF-R expression was studied in developing teeth of human embry os and fetuses between the 6th and 18th weeks of gestation, using a mo noclonal mouse-anti-human NGF-R antibody. In contrast to earlier findi ngs in rodents, the NGF-R expression of the human dental papilla was f ound to be transient. NGF-R was present in the condensing ecto-mesench ymal cells of the dental papilla in the early cap stage tooth germ. In later developmental stages, a shift of the NGF-R expression from the papilla to the cytoplasmic membrane of the inner enamel epithelium (IE E) was demonstrated. As in rodent odontogenesis, the NGF-R immunoreact ivity of the IEE remained until the odontoblasts started secretion of predentinal matrix in the late bell state. The mitotic activity in the IEE was detected by an antibody against proliferating cell nuclear an tigen (PCNA) and showed that the NGFR expression of the IEE decreased as the cell proliferation ceased. We propose that NGF-R may, be involv ed in differentiational and/or proliferative events of human odontogen esis.