Figure 1.

Effects of vasectomy on tumor outgrowth in TRAMP mice. (A) Design of Studies I and II. Vasectomy or sham surgery was performed at the age of 4 weeks. In groups of mice (Study II), bilateral orchiectomy or sham surgery was additionally performed at the age of 12 weeks. Macroscopic assessment was then performed at 10/16/24 (Study I) or 24 (Study II) weeks, and at the same time tissues were harvested for microscopic analysis. (B) Representative gross findings. (C) Representative histological findings (original magnification: ×400). (D) Immunohistochemistry of Ki-67 in prostate cancer (original magnification: ×200). The proliferation index (%) was determined by counting at least 500 Ki-67-positive/negative cancer cells in each mouse (n = 2 for sham/poorly differentiated at 24 weeks; n = 3 for other groups at 24 weeks).