Changes in cell adhesion molecules during follicular atresia in porcine ovaries

Determination of the expression level and localization of cell adhesion molecules is crucial for understanding the mechanism of maintenance and remodeling of the ovarian follicle structure. We immunocytochemically investigated expression of the cell adhesion molecules, "classic" cadherins and β-catenin, in developing and/or atretic follicles of porcine ovaries. Healthy follicles showed strong staining for cadherin-8 and β-catenin in granulosa cells tightly attached to the basement membrane, and moderate/weak staining was seen on the inner surface of the granulosa cell layer. Strong VE-cadherin expression was seen in a single cell layer attached to the basement membrane in the theca interna layer of healthy follicles. The expression of cadherin-8, β-catenin and VE-cadherin decreased during follicular atresia. No positive staining was observed for R-cadherin, E-cadherin, T-cadherin, BR-cadherin or P-cadherin, and a weak positive reaction for N-cadherin was seen only in the granulosa cells of healthy and early atretic follicles. These findings indicate that cadherin-8, N-cadherin and VE-cadherin have important roles in follicular development and/or degeneration, and that decreases in the expression of these cadherins are involved in follicular atresia in porcine follicles.