Immunolocalization of anti-Müllerian Hormone and Its Receptor in Granulosa Cell Tumors in Mares

Granulosa cell tumor (GCT) is a sex-cord stromal tumor in mares and causes infertility. The objective of this study was to localize anti-Mullerian hormone (AMH) and its receptor, anti-Mullerian hormone receptor type 2 (AMHR2), in ovarian tissue samples obtained from 11 Thoroughbred mares diagnosed with GCT. Immunohistochemistry revealed positive immunostaining for both AMH and AMHR2 in the granulosa-like cells of GCT. Furthermore, double immunofluorescence staining revealed the presence of colocalization of AMH and AMHR2 in granulosa-like cells of GCT in mares. These findings suggest that granulosa-like cells of GCT are a target of AMH, suggesting that AMH may have paracrine and autocrine function on granulosa-like cells of GCT in mares. Moreover, this is the first report to demonstrate the colocalization of AMH and its receptor, AMHR2, in GCT-affected ovaries of mares by using double immunofluorescence staining.