Table 2.

Urethral striated muscle sex differences summary

Species	Sex	Histologic studies	Functional studies	References
Rat	Female	Striated muscle is thin and circular, prominently occupying the middle urethra. Type II fibers are predominant.	Urine flow disrupted by partial/full closure of urethra Lower max flow rate and shorter micturition time	Praud et al. [51] Lim et al. [52] Buffini et al. [56] Biérinx et al. [53] Streng et al. [59]
	Male	Striated muscle forms a thick layer. 100% type II fibers in the upper urethra. Luminal muscle contains a mix of type I and II fibers.
Human	Female	Striated muscle extends the length of the urethra and is composed of predominantly type I slow twitch fibers (87% vs. 13%).		Benoit et al. [60] Ho et al. [62]
	Male	Striated muscle extends from the membranous urethra over the prostate and has a mixture of both slow and fast twitch fibers (65% vs. 35%).