CD34 microvessel staining in mouse bladder. Membrane expression of CD34 (brown staining) indicates the presence of microvessels. Male UPII-SV40T animals were sham-operated (intact), castrated and administered DHT, or castrated at 24 weeks of age. Animals were euthanized and bladders harvested at 32 weeks of age. Tissue was formalin fixed and paraffin embedded. Examples of positive CD34 staining in the tumor urothelium are indicated with arrows. CD34 staining is also present in the stroma, corroborated by adjacent HE stained sections. Magnification: 200× original.