When enlarged which structure interferes with urination in the male

The penis includes three cylindrical spaces blood-filled sinuses of erectile tissue. The two larger ones, the corpora cavernosa, lie side by side. The third sinus, the corpus spongiosum, surrounds most of the urethra. When these spaces fill with blood, the penis becomes large and rigid erect. The scrotum is the thick-skinned sac that surrounds and protects the testes. The scrotum also acts as a climate-control system for the testes because they need to be slightly cooler than body temperature for normal sperm development.

The cremaster muscles in the wall of the scrotum relax to allow the testes to hang farther from the body to cool or contract to pull the testes closer to the body for warmth or protection.

The testes are oval bodies that average about 1. Usually the left testis hangs slightly lower than the right one. The testes have two primary functions:. Producing testosterone the primary male sex hormone. The epididymis consists of a single coiled microscopic tube that measures almost 20 feet 6 meters in length. The epididymis collects sperm from the testis and provides the environment for sperm to mature and acquire the ability to move through the female reproductive system and fertilize an ovum.

One epididymis lies against each testis. The vas deferens is a firm tube the size of a strand of spaghetti that transports sperm from the epididymis. One such duct travels from each epididymis to the back of the prostate and joins with one of the two seminal vesicles.

In the scrotum, other structures, such as muscle fibers, blood vessels, and nerves, also travel along with each vas deferens and together form an intertwined structure, the spermatic cord. The urethra serves a dual function in males. Anejaculation is the condition of being unable to ejaculate.

Testes ducts, which include the seminiferous tubules and vas deferens, are involved in the creation or transportation of sperm.

Inside the Human Testes : Diagram of cross-section of testes: 1: Testicular septa 2: Convoluted seminiferous tubules 3: Testicular lobules 4: Straight seminiferous tubules 5: Efferent ductules 6: Rete testis.

Seminiferous tubules, located in the testes, are where meiosis occurs and the gametes spermatozoa are created. The seminiferous tubules are formed from primitive sex cords from the gonadal ridge.

The epithelium of the tubule consists of tall, columnar cells called Sertoli cells. Between the Sertoli cells are spermatogenic cells, which differentiate through meiosis to become sperm cells. There are two types of seminiferous tubules: convoluted, located toward the lateral side, and straight, as the tubule comes medially to form ducts that will exit the testis.

The efferent ducts connect the rete testis with the initial section of the epididymis. There are two basic types of efferent ductule structure. The ductuli are unilaminar and composed of columnar ciliated and nonciliated absorptive cells. The ciliated cells stir the luminal fluids, which may help ensure homogeneous absorption of water from the fluid produced by the testis.

This results in an increase in the concentration of luminal sperm. The epithelium is surrounded by a band of smooth muscle that helps to propel the sperm toward the epididymis. Histiological Representation of Seminferious Tubules : Seminiferous tubule in cross-section large tubular structure: center of image with sperm black, tiny, ovoid bodies furthest from the outer edge of the tubular structure.

The ductus vas deferens, also called the sperm duct, extend from the epididymis on each side of the scrotum into the abdominal cavity through the inguinal canal, an opening in the abdominal wall for the spermatic cord. The spermatic cord is a connective tissue sheath that contains the vas deferens, testicular blood vessels, and nerves. The smooth muscle layer of the vas deferens contracts in waves of peristalsis during ejaculation.

Two ducts connect the left and right epididymis to the ejaculatory ducts in order to move sperm. In humans, each tube is about 30 centimeters a foot long, 3 to 5 mm in diameter, and surrounded by smooth muscle. The sperm are transferred from the vas deferens into the urethra, collecting secretions from the male accessory sex glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which provide the bulk of semen.

The procedure of deferentectomy, also known as a vasectomy, is a method of contraception in which the vas deferens are permanently cut, though in some cases it can be reversed. A modern procedure that does not include cutting the ducts involves injecting an obstructive material into the ductus to block the flow of sperm.

Research in male contraception has focused primarily on the vas deferens with the use of the intra-vas device and reversible inhibition of sperm under guidance. The accessory sex glands, including the seminal, prostate glands, and bulbourethral glands, produce seminal fluid and clean and lubricate the urethra.

Each seminal gland forms as an outward growth of the wall of ampulla of each vas deferens. They are curled and folded within the gland and can spread out to approximately 5 cm, but the unfolded length is approximately 10 cm.

The excretory duct of the seminal gland opens into the vas deferens as it enters the prostate gland. The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen.

Lipofuscin granules from dead epithelial cells give the secretion its yellowish color. Seminal vesicle fluid is alkaline, resulting in human semen with a mildly alkaline pH. This helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm.

The vesicle produces a substance that causes the semen to become sticky after ejaculation, thought to help keep the semen near the cervix. The thick seminal vesicle secretions contain proteins including enzymes , mucus, fructose, vitamin C, flavins, phosphorylcholine, and prostaglandins. The high fructose concentrations provide nutrient energy for the spermatozoa when stored in semen in the laboratory.

Spermatozoa ejaculated into the vagina are not likely to have contact with seminal vesicular fluid, but transfer directly from the prostatic fluid into the cervical mucus as the first step on their travel through the female reproductive system. Seminal vesicle fluid is expelled under sympathetic contraction of the muscularis muscle coat. In vitro studies have shown that sperm expelled together with seminal vesicular fluid show poor motility and survival and less-protected chromatin.

Thus, the exact physiological importance of seminal vesicular fluid is unclear. It may be a developmental rest, such as in some rodents where the last part of the ejaculate forms a spermicidal plug to reduce the chances for sperm from a later-arriving male to proceed to the oocyte.

Prostate : Prostate with seminal vesicles and seminal ducts, viewed from the front and above, including the urethra, seminal vesicle, vas deferens, ampulla, ejaculatory duct, and isthmus. The prostate surrounds the urethra just below the urinary bladder and can be felt during a rectal exam.

It is the only exocrine organ located in the midline in humans and similar animals. Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. The prostate is sheathed in the muscles of the pelvic floor, which contract during the ejaculatory process. The prostatic fluid is expelled in the first ejaculate fractions, together with most of the spermatozoa.

In comparison with the few spermatozoa expelled in seminal vesicular fluid, those expelled in prostatic fluid have better motility, longer survival, and better protection of the genetic material. The prostate also contains some smooth muscles that help expel semen during ejaculation. To work properly, the prostate needs male hormones e. Some male hormones are produced in small amounts by the adrenal glands. However, dihydrotestosterone regulates the prostate. A healthy human prostate is slightly larger than a walnut in adult males, with a weight ranging between 7 and 16 grams.

Bulbourethral Gland : Image shows internal view of penis and male sexual anatomy. The bulbourethral gland is labeled at center left. Bulbourethral glands are located posterior and lateral to the membranous portion of the urethra at the base of the penis, between the two layers of the fascia of the urogenital diaphragm in the deep perineal pouch. They are enclosed by transverse fibers of the sphincter urethrae membranacea muscle.

The bulbourethral glands are compound tubulo-alveolar glands, each approximately the size of a pea. They are composed of several lobules held together by a fibrous covering.

Each lobule opens into a duct that joins with the ducts of other lobules to form a single excretory duct. This duct is approximately 2.

The glands gradually diminish in size with advancing age. During sexual arousal, each gland produces a clear, salty, viscous secretion known as pre-ejaculate.

This fluid helps to lubricate the urethra for spermatozoa to pass through, neutralizes traces of acidic urine in the urethra, and helps flush out any residual urine or foreign matter. It is possible for this fluid to pick up sperm remaining in the urethral bulb from previous ejaculations and carry them out prior to the next ejaculation.

Privacy Policy. Skip to main content. The Reproductive System. Search for:. The Male Reproductive System. Anatomy of the Male Reproductive System The male reproductive system includes external penis, scrotum, epididymus, and testes and internal accessory organs.

Learning Objectives Distinguish among the parts and functions of the male reproductive system. The scrotum changes size to maintain the right temperature.

When the body is cold, the scrotum shrinks and becomes tighter to hold in body heat. When it's warm, it gets larger and floppier to get rid of extra heat. This happens without a guy ever having to think about it. The brain and the nervous system give the scrotum the cue to change size.

The accessory glands , including the seminal vesicles and the prostate gland , provide fluids that lubricate the duct system and nourish the sperm. The urethra is the channel that carries the sperm in fluid called semen to the outside of the body through the penis. The urethra is also part of the urinary system because it is also the channel through which pee passes as it leaves the bladder and exits the body.

The penis is actually made up of two parts: the shaft and the glans. The shaft is the main part of the penis and the glans is the tip sometimes called the head. At the end of the glans is a small slit or opening, which is where semen and urine exit the body through the urethra yoo-REE-thruh. The inside of the penis is made of a spongy tissue that can expand and contract. All boys are born with a foreskin , a fold of skin at the end of the penis covering the glans.

Some boys are circumcised, which means that a doctor or clergy member cuts away the foreskin. Circumcision is usually done during a baby boy's first few days of life. It's not medically necessary, but parents who choose to have their sons circumcised often do so based on religious beliefs, concerns about hygiene, or cultural or social reasons. Boys who have circumcised penises and those who don't are no different: All penises work and feel the same, regardless of whether the foreskin has been removed.

When a baby boy is born, he has all the parts of his reproductive system in place, but it isn't until puberty that he is able to reproduce. When puberty begins, usually between the ages of 9 and 15, the pituitary gland — located near the brain — secretes hormones that stimulate the testicles to produce testosterone.

The production of testosterone brings about many physical changes. Although the timing of these changes is different for every guy, the stages of puberty generally follow a set sequence:. A male who has reached puberty will produce millions of sperm cells every day.

Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules. At birth, these tubules contain simple round cells.