Many infertile MMTV-Fst males have serum hormone levels and testes and seminal vesicle weights that are identical to WT males. A) Serum testosterone levels in WT (n = 16) and MMTV-Fst (n = 17) male founder mice (*P < 0.05). B) Serum FSH in WT and MMTV-Fst F1 offspring from transgenic lines B and C. WT littermates from both transgenic lines are combined (n = 14), FST B (n = 6; **P < 0.01), FST C (n = 4). C) Serum LH in WT and FST F1 offspring from transgenic lines B and C. WT littermates from lines B and C are combined (n = 14), FST B (n = 6; *P < 0.05), FST C (n = 4). D) Testes weight relative to body weight in FST lines A (n = 3), B (n = 5; ***P < 0.001) and C (n = 6; *P < 0.05) and WT littermates combined from all three lines (n = 20). E) Seminal vesicle weight relative to body weight in FST lines A (n = 3), B (n = 5; *P < 0.05) and C (n = 6) and WT littermates combined from all three lines (n = 20).