HISTOLOGY OF THE MALE REPRODUCTIVE SYSTEM
The male reproductive system is adapted for internal fertilization. The
penis is a structure that has evolved to deposit sperm safely within the
female’s body. The tube that passes through the penis, the urethra, has
two functions. It is the pathway for sperm out of the body as well as the
pathway for urine to leave the body after having been stored in the uri-
nary bladder. At the time of sexual excitement, a valve closes. This valve
prevents the bladder from releasing urine. At the same time, nerve
impulses from the brain cause blood vessels in the penis to relax. Blood
rushes in and fills empty spaces...
