Anti-Müllerian hormone immunolocalization in growing follicles of replacement gilts culled due to anestrus

Abstract

In female pigs, the anti-Müllerian hormone (AMH) produced by granulosa cells of developing follicles plays an important role in ovarian reserves of follicles and serum AMH levels are the biological marker of gilt reproductive performance. In the present study, we determined the AMH expression during follicular growth in replacement gilts culled due to anestrus by immunohistochemical technique. A total of 20 reproductive organs from crossbred Landrace  Yorkshire gilts were collected from swine commercial farms in Thailand and categorized by the reasons for culling, i.e., the anestrus group (n=12) and other causes not related to reproduction as the control group (n=8). As expected, the AMH immunolocalization in control gilts was markedly observed in most granulosa cells of healthy preantral, early antral, large antral and preovulatory follicles. The AMH immunostaining in the granulosa cells of most presumably healthy follicles in anestrus gilts depicted weak immunoreaction and the intensity score was significantly lower (P<0.05) than the control gilts. Certainly, the granulosa cells within the atretic follicles in both the control and anestrus groups were faint from AMH immunoreaction. The findings indicate that the low intensity of AMH immunoexpression found in the granulosa cells might be associated with a decreasing of serum AMH level in anestrus gilts. This phenomenon confirms that the insufficient physiological function of AMH during follicular growth is relevant to the cause of anestrus in replacement gilts.