AQP 9 immunohistochemical staining intensity quantification in the rat efferent ductules. Castration significantly reduced the AQP9 expression in the efferent ductules compared with controls. Similar result was found in the corn-oil treated group. 3β-diol, as well as estradiol and DHT, restored the efferent ductules AQP9 staining intensity to control level. Values represent mean ± SEM; n = 3 in each group; (*) = P ≤ 0,05 when compared to control group; (‡) = P ≤ 0,05 when compared to castrated group.