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 p75NGFR) can mediate cell growth and differentiation of non-neuronal cells. NGF-R expression was studied in developing teeth of human embryos and fetuses between the 6th and 18th weeks of gestation, using a monoclonal mouse-anti-human NGF-R antibody. In contrast to earlier findings in rodents, the NGF-R expression of the human dental papilla was found to be transient. NGF-R was present in the condensing ecto-mesenchymal 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 (IEE) was demonstrated. As in rodent odontogenesis, the NGF-R immunoreactivity 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 antigen (PCNA) and showed that the NGF-R expression of the IEE decreased as the cell proliferation ceased. We propose that NGF-R may, be involved in differential and/or proliferative events of human odontogenesis.