Expression of nectin-2 in mouse granulosa cells

Abstract

Objective: The development and maturation of the ovarian follicles are characterized by structural changes that require components involved in cell–cell adhesion systems. Recently a novel group of cell adhesion molecules named nectins has been identified. The present study examined expression and cell-specific localization of nectins during mouse follicular development. Study design: Expression of nectins in mouse ovary was investigated by immnuoblot analysis and immunohistochemistry. More precise localization was determined by electron microscopy. Results: Immunoblot analysis revealed expression of nectin-2 and nectin-3 but not nectin-1 in ovarian granulosa cells. Immunohistochemistry demonstrated expression of nectin-2 at cell–cell adhesion sites of granulosa cell layer in the primary and preantral follicles. Especially, intense immunoreactivity of nectin-2 accumulated around the zona pellucida. In antral follicles, the intensity of nectin-2 expression on granulosa cells was decreased. By electron microscopy nectin-2 was detected not only on thin extensions of granulosa cells penetrating the zona pellucida, but also on the attachment sites between thin extensions of granulosa cells and oocyte surface. Conclusion: The restricted expression of nectin-2 in the granulosa cells of primary and preantral follicles might reflect some of the molecular changes in cell–cell adhesion during early follicular development.