Urethral anatomy after hyaluronic acid injection for 4 and 12 weeks. Injected gel hyaluronic acid stably existed around the urethra. The size of the residual hyaluronic acid was not different from 4 weeks (A) to 12 weeks (B). Normal rat urethral anatomy was also performed as control (C). Hyaluronic acid is indicated with an asterisk, and the urethra is indicated with an arrow.