Amhr2, the Anti-Müllerian hormone type II receptor, is a key component in the AMH signaling pathway. AMH, a member of the Transforming Growth Factor-β family, signals through Amhr2. Amhr2 is expressed in mesenchyme adjacent to the Müllerian ducts, as well as in Sertoli, Leydig, and granulosa cells. It plays a crucial role in male differentiation by mediating the regression of Müllerian ducts in mammalian fetuses. Additionally, it is involved in various reproductive processes in both males and females, such as regulating germ cell development and folliculogenesis [1,2,3].

In mammals, Amhr2 mutations lead to Persistent Müllerian Duct Syndrome (PMDS), where affected males retain Müllerian duct-derived tissues like the uterus and oviducts [1,2,5]. In Amh mutant female mice, there is accelerated ovarian primordial follicle recruitment, suggesting Amhr2's role in regulating germ cells [1]. In Japanese flounder, amhr2-deficient mutants generated using the CRISPR/Cas9 system showed male-to-female sex reversal, indicating that Amh/Amhr2 signaling causes masculinization by inhibiting estrogen synthesis during gonadal sex differentiation [4].

In conclusion, Amhr2 is essential for normal reproductive development and function. Studies using gene-knockout models in mice and other species have revealed its key role in male sexual differentiation, germ cell regulation, and sex determination in fish. Understanding Amhr2 is crucial for comprehending the mechanisms underlying reproductive disorders such as PMDS and for further research in reproductive biology [1,2,4,5].