Distribution of C-CAM in developing oral tissues.

C-CAM is a cell surface glycoprotein that is involved in cell adhesion and may play a role in histogenesis and organogenesis. It is a member of the carcinoembryonic antigen (CEA) gene family, which is a subfamily of the immunoglobulin gene superfamily. We have analyzed the expression of C-CAM during normal and disturbed craniofacial development in the mouse by immunohistochemistry and in situ hybridization. Developmental disturbances were induced by retinoic acid (RA) treatment of pregnant mice. Normal and malformed fetuses were examined on days 14, 15, 16, 17 and 18 of gestation. The expression of C-CAM was detected first at day 16. With age, the signal became gradually stronger. C-CAM was detected in the epithelia of both ectodermal and mesodermal origin, including oral and respiratory epithelia, epithelia of the developing vessels, glands and their ducts. In the RA-treated fetuses, the expression of C-CAM was higher in the epithelium of the oral cavity than in that of the nasal cavity, with a distinct borderline between differentiating nasal and oral epithelium of the palatal shelves. However, the submucosal nasal glands and ducts showed higher expression than oral glands in both normal and RA-treated mice. The expression of C-CAM did not differ significantly between control and RA-treated animals. The presence of C-CAM in all proliferating craniofacial epithelia indicates that this molecule may play an important role in development.