Cell-cell interaction, and particularly cell-cell adhesion and gap junctional communication, appear to play an important role during embryo development and tissue formation. In addition, at least in the case of desmosomal- and caherin-based cell adhesion, these processes may have a decisive role in the formation of carcinomas, tumors and metastases. Both in mammals and lower vertebrates, desmosomal structures and gap junctions have been described in close proximity in the ovarian follicle, although their molecular composition and specific physiological role during follicle development remains to be elucidated. Recent experiments using specific molecular approaches have sugested that cell adhesion may require signaling trough gap junctional pathways, and thus both cell contact structures appear to be interdependent. The aim of the present project is to develop new information on the molecular composition and specific cellular localization of the desmosomal proteins in the vertebrate ovarian follicle. In addition, as a novel approach, the specific interactions between desmosomal and gap junctions, and their possible significance during follicle development, will be investigated using specific antisera and transfection of cDNAs encoding stable dominant-negative inhibitors.