Oxandrolone was found incapable of supporting reproductive development in the young male rat.15 Weight of testes, prostate gland, and seminal vesicles were all below controls, and Leydig cells were severely depleted. Again, it was not ruled out that reduced estrogen levels of the oxandrolone-treated animals might have been to blame, so this does not actually prove a non-AR-dependent mechanism for reproductive development. It does indicate that androgens other than testosterone combined with low estrogen levels can result in fertility problems in the rat, and therefore long-term use of nonaromatizing steroids might affect sperm count in the human as well.
here is the full article.
http://www.mesomorphosis.com/articles/pharmacology/differences-between-anabolic-steroids.htm