A: Immunofluorescence detection localises AR to all smooth muscle cells of testicular blood vessels (arrow) and approximately 50% of vascular endothelial cells (solid arrowhead). AR is not detected in the remaining endothelial cells (outline arrowhead). Non-specific staining of arteriole elastic fibres occurs in even the absence of primary antibody (inset, arrow). B: Colocalisation of YFP immunofluorescence with the specific endothelial marker CD31 demonstrates that Tie2-Cre is active in endothelial cells of the testicular blood vessels (arrows). Tie2-Cre is also active in a proportion of testicular interstitial cells (arrowhead) C: Double immunofluorescence staining for AR and YFP demonstrates colocalisation of AR and YFP in a proportion of testicular vascular endothelial cells (arrowheads). D: YFP-expressing interstitial cells do not express AR (arrows). Scale bars are 20 μm.