Reproduction Abstracts

Introduction: Oocytes develop in cysts of interconnected cells that undergo breakdown and become surrounded individually by granulosa cells to form primordial follicles. Mechanisms controlling cyst breakdown and primordial follicle formation are not well understood but cell adhesion molecules (CAMs) may a play role. Our model is that CAMs keep oocytes in cysts and must be down regulated for primordial follicles to form. A second set of CAMs would then be necessary for interactions between oocytes and granulosa cells during follicle formation. This model is supported by work in a hamster model (Wang & Roy 2010).

Materials and methods: Western blotting and immunocytochemistry were performed on mouse ovaries from 17.5 dpc to PND5 using antibodies against E-cadherin and N-cadherin to test for expression and cellular localization. To determine the role of each CAM, PND1 ovaries were cultured for 5 days in the presence function blocking antibodies and examined using confocal microscopy.

Results and discussion: Both E-cadherin and N-cadherin were detected in mouse ovaries from 17.5 dpc to PND5. E-cadherin was localized to oocytes in germ cell cysts and primordial follicles while N-cadherin was expressed in both oocytes and granulosa cells. CAM function blocking antibodies in ovary organ culture had no effect on cyst breakdown, oocyte number, or follicle development. This may be because PND1 ovaries were used for culture but cyst breakdown begins 2 days earlier at 17.5 dpc and PND1 may be too late to alter cyst breakdown. Organ culture experiments with CAM blocking antibodies are now being repeated using 17.5 dpc ovaries.