The distribution pattern of the hyaluronan receptor CD44 during human tooth development

The aim was to investigate the expression pattern of the major cell-surface hyaluronan receptor CD44, as there are no existing data on its presence or absence in human dental structures at different developmental stages. Immu nohistochemical localization of CD44 was studied using a monoclonal antibod y, H3, that specifically recognizes an epitope in the common backbone of al l CD44 isoforms. The dental lamina displayed a strong CD44 signal; the exte rnal enamel epithelium was negative. In the coronal region of the tooth ger m the presecretory ameloblasts showed an intense reaction whereas the less differentiated inner enamel epithelial cells showed no signal at the cervic al loop where they meet the external enamel epithelium. In the stellate ret iculum a moderate reaction was detected. The secretory ameloblasts and the stratum intermedium showed a strong cell-surface CD44 signal. A strong sign al was also observed on the odontoblasts and their processes. In the pulp, close to the odontoblastic layer, weak labelling was seen in the walls of c apillary vessels. The distribution of CD44 in the human tooth germ correspo nds to that of hyaluronan in most locations, suggesting that during tooth d evelopment this transmembrane protein plays an important part in hyaluronan -mediated events. (C) 2001 Elsevier Science Ltd. All rights reserved.