Ethics Statement
All animal procedures were approved by the Johns Hopkins University School of Medicine Animal Care and Use Committee. Mice were anesthetized with 50 mg/kg Ketamine + 5 mg/kg Xylazine by intraperitoneal injection. All efforts were made to minimize animal suffering.
Blood Sampling and Hormone Measurements
After collection as above, blood was kept for 1 h at room temperature for LH measurements, or at 4 C for testosterone measurements. All test tubes were centrifuged at 3,000 x g for 10 minutes, and serum was separated. Serum LH was measured at the University of Virginia, Center for Research in Reproduction, by immunoradiometric assay [19]. Serum and intratesticular testosterone were measured by radioimmunoassay (RIA) [20].