Ejaculation: Behind the scenes A duct called the ductus deferens, surrounded here by smooth muscle tissue, plays a key role in male orgasms. Sperm is first produced in the testes. During sex, muscles in the walls of the ductus deferens contract and propel sperm through the prostate, into the urethra, and eventually out of the tip of the penis (ductus deferens means “carrying-