Ovarian stage-dependent expression of GDF9, BMP15, and AMH in domestic cats

Growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15), and anti-Müllerian hormone (AMH), members of the transforming growth factor-beta (TGF-β) superfamily, play critical roles in follicular development and oocyte maturation and are utilized as prognostic markers of fertility. This study aims to investigate the expression patterns of GDF9, BMP15, and AMH in different follicular developmental stages and across distinct reproductive phases in the feline ovary. Feline ovaries (N = 24) were divided into four ovarian statuses: prepubertal (n = 6), follicular (n = 6), luteal (n = 6), and inactive (n = 6). The protein expression of GDF9, BMP15, and AMH was observed by immunohistochemistry and Western blotting. GDF9 and BMP15 exhibited significantly higher expression in primordial and primary follicles compared to antral follicles during the follicular stage. Conversely, AMH expression was significantly elevated in secondary and antral follicles. Western blotting analysis did not reveal statistically significant differences in the expression levels of GDF9 and BMP15 among the different reproductive stages, while higher expression of AMH was observed during prepubertal stage. The differential expression of GDF9, BMP15, and AMH across ovarian cell types and reproductive phases suggests their distinct roles in folliculogenesis and ovarian function. The prominent expression of GDF9 and BMP15 in primordial and primary follicles underscores their essential roles in early folliculogenesis, while the increased AMH expression in antral follicles during the follicular phase may indicate its involvement in later follicular development and selection.