A 62-year-old man has

increased urinary frequency, including nocturia (getting up multiple times

during the night to urinate). A physical exam reveals an enlarged prostate,

which is obstructing his urinary flow (the prostate surrounds the urethra below

the bladder). The initial response of the bladder to this condition is

hypertrophy of the tissue that generates urinary force. Which tissue is

hypertrophied in this patient?