Estrogen receptor-α immunohistochemistry in the efferent ductules. ERα is abundant in the ductules of most species examined. Represented here are ductules from the rat, mouse, dog and cat [109, 110, 130]. Ciliated (C) and nonciliated (N) cells are strongly positive in all these species, except the cat, where ciliated cells show weak staining. Bar = 25 μm.