The immunohistochemical localization of the interferon-gamma and granulocyte colony-stimulating factor receptors during early amelogenesis in rat molars.

Previous studies, in which the known janus kinase and signal transducer and activator of transcription (STAT) isoforms were immunohistochemically mapped in developing rat molars, implicated a sizeable list of cytokine superfamily receptor (CSR)/signal-transduction pathway (STP) linkages in the cells of the enamel organ involved in the events leading directly to early amelogenesis. Various combinations of upregulated janus kinases and STATs are known to be linked to single or small groups of CSRs. On the basis of the previous observations it was hypothesized that the interferon-gamma receptor (IFNgamma r) and the granulocyte colony-stimulating factor receptor (G-CSF receptor) would be localized in specific sites in the cells of the enamel organ during early amelogenesis. To verify this, whole-head, freeze-dried sections were here obtained at the level of the mandibular first and second molar from newborn and 5-day-old rats. These sections were not demineralized or fixed, reducing the possibility of false-negative results. Antibodies to the IFNgamma r and the G-CSF receptor were localized using a modification of the avidin-biotin complex method. In the newborn rats, IFNgamma r was localized in the preameloblasts in the cervical loop, the proximal and distal ends of presecretory ameloblasts, the outer enamel epithelium, the dental lamina, and in bone. In 5-day-old rats, it was confined to the proximal ends of the presecretory and secretory ameloblasts. The G-CSF receptor was observed in the molars of newborn rats in the preameloblasts, the proximal and distal ends of the presecretory ameloblasts, outer enamel epithelium, and in bone. In 5-day-old rats, G-CSF receptor was localized in the preameloblasts, the proximal ends of presecretory and secretory ameloblasts, the stellate reticulum, the outer enamel epithelium, and in bone. These findings indicate that the IFNgamma r and the G-CSF receptor, and their downstream STP linkages, are upregulated in the cells of the enamel organ and may be involved in the events leading directly to early enamel formation.