Figure 2. Aging leads to voiding changes as measured by ultrasound. (A) Ultrasound image showing the three urethra regions. (B) The urethral diameter is the largest at the bladder neck with a significant drop at the prostatic urethra before the diameter increases at the post-prostatic urethra in young mice. The post-prostatic urethra, while larger than the prostatic urethra is still significantly smaller than the bladder neck diameter. The penile urethra is slightly smaller than the post-prostatic urethra but significantly smaller than the bladder neck. There is a significant decrease in bladder neck diameter with age and a slight decrease at all other locations with age. The decrease of lumen diameter between bladder neck and diameter is still significant in aged mice. (C) The mean velocity through the urethra of young mice show a significant decrease between prostatic and post-prostatic and a significant increase between post-prostatic and penile consistent with a narrowing of lumen diameter. (D) The mean velocity is highest at the prostatic urethra in aged mice, but the changes in velocity is lost with age. The mean velocity of flow in aged mice is lower than mean velocity in young mice. *, p-value < 0.05; ***, p-value < 0.001; ****, p-value < 0.0001.