Localization of bromodeoxyuridine-incorporating, p63- and p75NGFR- expressing cells in the human gingival epithelium

The objective of this study was to find the sites with proliferative activity in the human gingival epithelium, where stem cells are likely to exist. Gingival tissues were excised from 16 adult patients and immunohistochemically examined for the presence of bromodeoxyuridine (BrdU)-incorporating, p63- and low affinity nerve growth factor receptor (p75(NGFR))-expressing cells. BrdU-incorporating cells were rarely present in the junctional epithelium. The number of BrdU-incorporating cells in the sulcular and oral gingival epithelia was significantly higher than that found in the junctional epithelium (ANOVA, P < 0.01). A considerable number of p63-positive nuclei were detected in the basal layer to lower spinous layers in the sulcular and oral gingival epithelia, but only few p63-positive cells were present in the junctional epithelium. p75(NGFR)-positive cells were exclusively located in the basal layer in the sulcular and oral gingival epithelia, and in limited basal area in the junctional epithelium neighboring the sulcular epithelium. In the oral gingival epithelium, intense immunostaining of BrdU, p63 and p75(NGFR) was correspondingly observed on the base and side of the rete ridges. These areas probably exhibit high proliferative activity owing to the presence of stem cells.