Polymorphism, expression and structure analysis of key genes in the ovarian steroidogenesis pathway in sheep (Ovis aries) oleh Wen‐Ping Hu, Ming‐Qiu Liu, Zhi‐Long Tian, Qiu‐Yue Liu, Zhuang‐Biao Zhang, Ji‐Shun Tang, Xiao‐Yun He, Yan‐Yan Zhu, Yuan‐Yuan Wang, Ming‐Xing Chu