testis

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testis

 [tes´tis] (L.)
the male gonad; either of the paired, egg-shaped glands normally found in the scrotum; called also testicle. The testes produce the spermatozoa (the male reproductive cells) and testosterone (the male sex hormone), which is responsible for the secondary sex characters of the male.
A, Testis; B, production of spermatozoa.


If the testes are removed (castration, bilateral orchiectomy) before puberty, the male is sterile and will never develop all the adult male secondary sex characters. If they are removed after puberty, the male becomes sterile and his secondary sex characters will diminish unless he receives injections of male hormones. With aging, there is a gradual decrease in the production of testosterone.

In the fetus in utero, the testes lie close to the kidneys. During approximately the seventh month of fetal life, the testes begin to descend through the abdominal wall at the groin and enter the scrotum. As they descend they are accompanied by blood vessels, nerves, and ducts, all contained within the spermatic cord. The passageway through which the testis and spermatic cord descend is called the inguinal canal. Failure of a testis to descend into the scrotum is called cryptorchidism.

The testis is divided internally into about 250 compartments or lobules, each of which contains one to three small convoluted tubules, within which spermatozoa are produced. When mature, the spermatozoa leave the tubules and enter the epididymis (situated on top of and behind each testis), where maturation is completed. The spermatozoa are stored in the epididymis until such time as they are mixed in the semen and ejaculated during coitus. (See also reproduction and male reproductive organs.)
Cancer of the Testis. Testicular cancer accounts for about 12 per cent of all cancer deaths in young men in North America and is second only to accidents as a cause of death in men between the ages of 20 and 35 years. It is one of the most curable forms of cancer when detected early and treated promptly. Men most at risk for testicular cancer are those who have an undescended or partially descended testicle.



In order to ensure early detection of cancer of the testis, men are urged to conduct a monthly self-examination of the testes. The self-examination involves the use of both hands to examine each of the testes. The index and middle fingers are placed below the testis and the thumbs on top. With a gentle motion each testis is rolled between the thumbs and fingers to discover any lump (usually about the size of a pea), thickening, or change in the consistency of the tissues. It is important that the man become familiar with the feel of the epididymis so that he doesn't confuse this normal structure with an abnormal lump. Should a lump or any other abnormality be found, a doctor should be consulted immediately. The American Cancer Society publishes several pamphlets that explain the procedure for testicular self-examination and give additional information on testicular cancer. Diagnosis of testicular cancer is confirmed by biopsy of the suspect testis. There are three stages of classification for malignancy of the testis: Stage I: the tumor is confined to the affected testis; Stage II: the malignancy has spread to the regional lymph nodes; and Stage III: there is metastasis to other organs, such as the lung and liver.

Treatment of testicular cancer (simple orchiectomy for Stage I malignancy) may or may not render the patient impotent and sterile. If there is no metastasis, only the affected testis need be removed. The remaining testis will retain its normal function and the patient should be able to have normal sexual intercourse and be fertile. However, if more radical surgery and radiation therapy are called for and both testes and the lymph nodes are dissected, and if there has been no damage to nerves during surgery, the patient may be able to have sexual intercourse but no seminal fluid will be emitted. A young man who is looking forward to having children may consider banking his sperm prior to surgery so that he might father children by artificial insemination.
Testicular self-examination. (Redrawn from For Men Only. New York, American Cancer Society.)
abdominal testis an undescended testis located in the abdominal cavity.
canalicular testis an undescended testis located between the internal and external inguinal rings.
cryptorchid testis undescended testis.
ectopic testis one lodged in a location outside of the normal pathway of descent.
gliding testis an undescended testis that can reach the top of the scrotum but then glides back up.
obstructed testis an ectopic testis whose descent was prevented by a fascial sheet at the entrance to the scrotum.
retained testis undescended t.
retractile testis a testis that can descend fully into the scrotum but moves freely up into the inguinal canal.
undescended testis
1. a testis in the normal pathway of descent but failing to descend into the scrotum; see also cryptorchidism. Called also cryptorchid or retained testis.
vanishing testis one that was originally present in the fetus but atrophied in utero because of torsion.

tes·tis

, pl.

tes·tes

(tes'tis, -tēz), [TA]
One of the two oval male gonads (reproductive glands), located in the cavity of the scrotum. The seminiferous tubules of the testis are the site of spermatogenesis and its Leydig cells secrete testosterone as well as estrogens and other androgenic steroid hormones.
See also: appendix testis.
[L.]

testis

/tes·tis/ (tes´tis) pl. tes´tes   [L.] the male gonad; either of the paired egg-shaped glands normally situated in the scrotum, in which the spermatozoa develop. Specialized interstitial cells (Leydig cells) secrete testosterone.
abdominal testis  an undescended testis in the abdominal cavity.
ectopic testis  one outside the normal pathway of descent.
obstructed testis  one whose normal descent is blocked, so that it goes into an inguinal pouch.
retained testis  undescended t.
retractile testis  one that can descend fully into the scrotum but then moves freely up into the inguinal canal.
undescended testis  one that has failed to descend into the scrotum, as in cryptorchidism.

testis

(tĕs′tĭs)
n. pl. tes·tes (-tēz)
1. One of the paired male reproductive organs that produce spermatozoa and male sex hormones in humans and other vertebrates.
2. An analogous gland in an invertebrate animal, such as a flatworm or a mollusk.

testis

[tes′tis] pl. testes [tes′tēz′]
one of the pair of male gonads that produces sperm and testosterone. The adult testes are suspended in the scrotum by the spermatic cords; in early fetal life they are contained in the abdominal cavity behind the peritoneum. Before birth they normally descend into the scrotum. The coverings of the testes are the skin and the dartos tunic of the scrotum, the external spermatic fascia, the cremasteric layer, the internal spermatic fascia, and the tunica vaginalis. Each testis is a laterally compressed oval body about 4 cm long and 2.5 cm wide that weighs about 12 g. It is positioned obliquely in the scrotum, with the cranial extremity directed ventrally and slightly laterally and the caudal end directed dorsally and slightly medially. The anterior border, lateral surfaces, and extremities of the organ are convex, free, smooth, and covered by the tunica vaginalis. The convoluted epididymis lying on the posterior border of the testis contains a tightly coiled tube that is about 20 feet long and connects with the vas deferens through which spermatozoa pass during ejaculation. Each testis consists of several hundred conical lobules containing the tiny coiled seminiferous tubules, each about 75 mm long, in which spermatozoa develop. In early life the tubules are pale in color, but in old age they become invested with yellow fatty matter. The tubules converge to form the rete testis, which is drained by the efferent ducts into the head of the epididymis. The testes are supplied with blood by the two internal spermatic arteries that arise from the aorta, are served by the testicular veins that form the pampiniform plexuses constituting the greater part of the spermatic cords, and are innervated by the spermatic plexuses of nerves from the celiac plexuses of the autonomic nervous system. Also called testicle. Compare ovary. See also scrotum. testicular, adj.
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Testis

testis

Either of the pair of male sexual organs, which are located in the scrotum and produce sperm—beginning in puberty and then throughout life—as well as testosterone.

tes·tis

, pl. testes (tes'tis, -tēz) [TA]
One of the two male reproductive glands, normally located in the cavity of the scrotum.
See also: appendix of testis
Synonym(s): orchis [TA] , didymus, testicle.
[L.]

testis

(tes'tis) plural.testes [L.]
Enlarge picture
TESTIS
The male gonad; testicle. It is one of two reproductive glands located in the scrotum that produce the male reproductive cells (spermatozoa) and the male hormones testosterone and inhibin. See: illustration

Anatomy

Each is an ovoid body about 4 cm long and 2 to 2.5 cm in width and thickness, enclosed within a dense inelastic fibrous tunica albuginea. The testis is divided into numerous lobules separated by septa, each lobule containing one to three seminiferous tubules within which the spermatozoa are produced by meiosis. The lobules lead to straight ducts that join a plexus, the rete testis, from which 15 to 20 efferent ducts lead to the epididymis. The epididymis leads to the ductus deferens, through which sperm are conveyed to the urethra. Between the seminiferous tubules are the interstitial cells (cells of Leydig), which secrete testosterone. Within the tubules are sustentacular cells, which secrete inhibin. The testes are suspended from the body by the spermatic cord, a structure that extends from the inguinal ring to the testis and contains the ductus deferens, testicular vessels (spermatic artery, vein, lymph vessels), and nerves.

Disorders

Hyperfunction (hypergonadism) may cause early maturity such as large sexual organs with early functional activity and increased growth of hair. Hypofunction (hypogonadism) is indicated by undeveloped testes, absence of body hair, high-pitched voice, sterility, smooth skin, loss of sexual desire, low metabolism, and eunuchoid or eunuch body type.

descent of testis

The migration of the testis from the abdominal cavity to the scrotum during fetal development.

displaced testis

A testis located abnormally within the inguinal canal or pelvis.

femoral testis

An inguinal testis near or superior to the femoral ring.

inverted testis

A testis reversed in the scrotum so that the epididymis attaches to the anterior instead of the posterior part of the gland.

perineal testis

A testis located in the perineal region outside the scrotum.

undescended testis

Cryptorchidism..

testis

One of the two male gonads, suspended in the scrotum by the spermatic cord. The testis, or testicle, contains the long, coiled seminiferous tubules in which the SPERMATOZOA are formed. Between the tubules are cells that secrete testosterone and other masculinizing steroid hormones and oestrogens.

testis

(pl. testes) the organ of the male animal, producing the male gametes, or sperms. It also produces ANDROGENS - male Dictionary of Biology 2005 9.5 2/6 /05 3:46 pm Page 465 sex hormones. See SCROTUM, SEMINIFEROUS TUBULES, GERMINAL EPITHELIUM, SERTOLI CELLS.

testis

the male gonad, the site of spermatogenesis, whence sperm are discharged via the vas deferens into the urethra at ejaculation. This and also testicular endocrine function (secretion of testosterone and related hormones) are under the control of gonadotrophic hormones from the anterior pituitary, and in turn of the hypothalamus.

testis

pl. testes [L.] the male gonad; either of the paired, egg-shaped glands normally situated in the scrotum; called also testicle. The testes produce the spermatozoa, the male reproductive cells, which are ejaculated into the female vagina during coitus, and the male sex hormone, testosterone, which is responsible for the secondary sex characters of the male.

ectopic testis
the testis is in an abnormal position away from the normal descent pathway.
nonscrotal testis
includes ectopic and cryptorchid testis.
retained testis
supernumerary testis
polyorchidism.
testis tubuli contorti
seminiferous tubule.
undescended testis
see cryptorchid. Called also retained testicle.

Patient discussion about testis

Q. Has anyone ever had Epididymitis? I was just diagnosed with it and want to know what to expect. Thanks

A. i had an ultrasound done once before,it revealed nothing was wrong,then i had a lower gi,it also showed nothing,at the present moment,my testicules are swollen a little,
slight pain,tenderness,problems with urination,and not
urinating very often,feel as if i"m not completing my
urination,feels like i have a bladder infection,with
an epididymis infection,this makes the 7th time i"ve
had this,i"d like to know why i keep getting it??? and
will it ever stay away??? is there a complete cure?
would a vasecemy cure it???

More discussions about testis