The testicular phenotypes in Tbc1d20 ZFN/ZFNmice. Tbc1d20 ZFN/ZFN testes appeared smaller in size when compared to controls (A); scale bar = 1 mm. H&E analysis identified disorganized Tbc1d20 ZFN/ZFN seminiferous tubules (C) when compared to highly organized seminiferous tubules in controls (B); scale bars = 50 μm. TRA54 immunostaining (green) in control tubules revealed small punctae and crescent-shaped staining consistent with spermatocytes and round spermatids respectively (D) and in Tbc1d20 ZFN/ZFN only TRA54 positive punctate staining was evident (E). PNA staining of control tubules identified the presence of acrosomes (F), whereas in Tbc1d20 ZFN/ZFN only PNA positive punctate staining was noted (G); scale bars = 25 μm. DNA was stained with DAPI (blue).