and secretion of the male sex hormone testosterone.
Lying close to the superior pole of each testis is the EPIDIDYMIS, a ductal system that collects and transmits sperm from the testes.
The two spermatic cords, each of which suspends and supplies a testis, are formed by the ductus deferens, arteries, veins, lymphatics, and nerves, bound together by connective tissue.
The ductus deferens is a small tube that connects the epididymis and ejaculatory duct. It ascends as part of the spermatic cord through the inguinal canal into the pelvic cavity and transmits the sperm to the ejaculatory duct.
The seminal vesicles are two pouches that lie between the bladder and the rectum. They secrete and store a fluid to be added to the secretion of the testes at the time of ejaculation.
The ductus deferens and the ducts from the seminal vesicles converge to form the short ejaculatory duct that leads into the prostatic urethra. Its function is the transportation of secretions.
The penis is composed of three cylindrical bodies of spongy cavernous tissue, bound together by connective tissue and loosely covered by a layer of skin. Two of the bodies, the corpora cavernosa, lie superiorly side by side; the third body, the corpus spongiosum, is median, lying in the groove between the other two. The dilated distal end of the corpus spongiosum is known as the glans penis. The cavernous tissue becomes greatly distended with blood during sexual excitement, causing erection of the penis. The loose skin of the penis folds back on itself at the distal end, forming the prepuce, or foreskin, and covers the glans. Frequently, the prepuce is surgically removed (circumcision) to prevent irritation and to facilitate cleanliness.
The prostate gland is made of smooth muscle and glandular tissue that surrounds the first part of the urethra. It resembles a chestnut in shape and size. It secretes an alkaline fluid to keep the sperm mobile and protect it from the acid secretions of the female vagina. This substance is discharged into the urethra as part of the ejaculate, or semen, during the sexual act.
Cowpers glands are two pea-sized bodies, one on either side of the membranous portion of the urethra, the excretory ducts of which open into the urethra. They secrete a mucouslike alkaline fluid during the sexual act to provide lubrication.
Semen is composed of sperm and secretions from the seminal vesicles, prostate, and Cowpers glands. It is discharged as the ejaculate during sexual intercourse. There are millions of sperm cells in the semen of each ejaculation, but only one is needed to fertilize the ovum. It is generally considered that fertilization of the ovum occurs while it is still in the uterine tube. Therefore, it is apparent that sperm cells can move actively in the seminal fluid deposited in the vagina and through the layers of the secretion lining the uterus and the uterine tube.
Although the prostate, seminal vesicles, and bulbourethral glands secrete most actively during sexual intercourse, a certain amount is being formed continuously. During periods of prolonged sexual abstinence, discharge of this accumulation may occur during sleep as a nocturnal emission or wet dream. This is an entirely normal condition and does not constitute a harmful or disease state; on the other hand, retention of these secretions in no way impairs health or the mental state.
At times, what appears to be semen may drip from the penis on straining to move bowels. This is the secretion of the prostate and seminal vesicles being forced out by the increased pressure within the abdominal cavity and forceful passage of feces through the rectum, which lies close to these structures. This occurrence does not indicate disease or infection if urethral discharge is present only during such acts of straining. Any continuing discharge should be examined for evidence of infection.