Kimaya :: Organs

The male reproductive system, like that of the female, consists of those organs whose function is to produce a new individual, i.e., to accomplish reproduction. This system consists of a pair of Testes and a network of excretory ducts (epididymis, ductus deferens (vas deferens), and ejaculatory ducts), seminal vesicles, the prostate, the bulbourethral glands, and the Penis.

External- Most of the male reproductive system is located outside of the man’s body. The external structures of the male reproductive system are the Penis, the scrotum and the testicles.

The Penis- it is the male copulatory organ. it is cylindrical pendant organ located in front of the scrotum and functions to transfer sperm to the Vagina. The body of the Penis is cylindrical in shape and consists of three internal chambers. These chambers are made up of special, sponge-like erectile tissue. This tissue contains thousands of large spaces that fill with Blood when the man is sexually aroused. As the Penis fills with Blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. The Skin of the Penis is loose and elastic to accommodate changes in Penis size during an erection. A loose fold of Skin, called the prepuce, or foreskin, covers the glans Penis.
Scrotum — The scrotum is the loose pouch-like sac of Skin that hangs behind the Penis. It contains the testicles (also called Testes), as well as many nerves and Blood vessels. The scrotum has a protective function and acts as a climate control system for the Testes. For normal sperm development, the Testes must be at a temperature slightly cooler than the body temperature. Special Muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth and protection or farther away from the body to cool the temperature.

Testis- Most men have two Testes. The Testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. The male gonads, Testes, or testicles, begin their development high in the abdominal cavity, near the kidneys. During the last two months before birth, or shortly after birth, they descend into the scrotum, a pouch that extends below the Abdomen, just behind the Penis. Each testis is an oval structure about 5 cm long and 3 cm in diameter. A tough, white fibrous connective tissue capsule, the tunica albuginea, surrounds each testis. There are about 250 lobules in each testis. Each lobule contains 1 to 4 highly coiled seminiferous tubules that converge to form a single straight tubule. Special cells present in these seminiferous tubules, called ‘cells of leydig’ produce the male sex hormones(sperms).

internal organs-The internal organs of the male reproductive system, also called accessory organs, include the duct system (epididymus, ductus deferens, Ejaculatory Duct),Seminal vesicle, Prostate gland, Bulbourethral Gland
Sperm cells pass through a series of ducts to reach the outside of the body. After they leave the Testes, the sperm passes through the epididymis, ductus deferens, Ejaculatory Duct, and Urethra.
Epididymis- Sperm leave the Testes through a series of efferent ducts that enter the epididymis. Each epididymis is a long (about 6 meters) tube that is tightly coiled. When the sperm leave the Testes, they are immature and incapable of fertilizing ova. They complete their maturation process and become fertile as they move through the epididymis. Mature sperm are stored in the lower portion, or tail, of the epididymis
Ductus Deferens- The ductus deferens, also called vas deferens, is a fibromuscular tube that is continuous with the epididymis. It begins at the bottom (tail) of the epididymis. just before it reaches the Prostate gland, each ductus deferens enlarges to form an ampulla. Sperm are stored in the proximal portion of the ductus deferens which is a component of the spermatic cord. peristaltic movements propel the sperm through the tube.
Ejaculatory Duct- Each ductus deferens, at the ampulla, joins the duct from the adjacent Seminal vesicle (one of the accessory glands) to form a short Ejaculatory Duct. Each Ejaculatory Duct passes through the Prostate gland and empties into the Urethra.

Seminal Vesicles- The paired seminal vesicles are saccular glands. Each gland has a short duct that joins with the ductus deferens at the ampulla to form an Ejaculatory Duct, which then empties into the Urethra. The fluid from the seminal vesicles is viscous and contains fructose, which provides an energy source for the sperm; prostaglandins, which contribute to the mobility and viability of the sperm; and proteins that cause slight coagulation reactions in the semen after ejaculation.
Prostate gland- it is a dense structure that is located just below the Urinary bladder. It is about the size of a walnut and encircles the Urethra as it leaves the Urinary bladder. Numerous short ducts from the substance of the Prostate gland empty into the prostatic Urethra. The secretions of the prostate are thin, milky colored, and alkaline. They function to enhance the motility of the sperm.
Bulbourethral Glands- they are paired glands and are small, about the size of a pea, and located near the base of the Penis. A short duct from each gland enters the the penile Urethra. In response to sexual stimulation, the bulbourethral glands secrete an alkaline mucus-like fluid. This fluid neutralizes the acidity of the urine residue in the Urethra, helps to neutralize the acidity of the Vagina, and provides some lubrication for the tip of the Penis during intercourse.
Seminal Fluid-Seminal fluid, or semen, is a slightly alkaline mixture of sperm cells and secretions from the accessory glands. Secretions from the seminal vesicles make up about 60 percent of the volume of the semen, with most of the remainder coming from the Prostate gland. The sperm and secretions from the Bulbourethral Gland contribute only a small volume. The volume of semen in a single ejaculation may vary from 1.5 to 6.0 ml. There are usually between 50 to 150 million sperm per milliliter of semen. Sperm counts below 10 to 20 million per milliliter usually present fertility problems. Although only one sperm actually penetrates and fertilizes the Ovum, it takes several million sperm in an ejaculation to ensure that Fertilization will take place.