*** Membrane covers [[Vagina and Vestibule - Anatomy & Physiology|vaginal]] opening except at oestrus and during [[Reproductive System - Anatomy & Physiology#Parturition|parturition]]. | *** Membrane covers [[Vagina and Vestibule - Anatomy & Physiology|vaginal]] opening except at oestrus and during [[Reproductive System - Anatomy & Physiology#Parturition|parturition]]. |