AskDefine | Define epididymis

Dictionary Definition

epididymis n : a convoluted tubule in each testis; carries sperm to vas deferens [also: epididymides (pl)]

User Contributed Dictionary

English

Noun

epididymis (plural epididymides)
  1. A narrow, tightly-coiled tube connecting the vas efferens from the rear of each testicle to its vas deferens, which sperm are stored during maturation.

Derived terms

Extensive Definition

The epididymis is part of the human male reproductive system and is present in all male mammals. It is a narrow, tightly-coiled tube connecting the efferent ducts from the rear of each testicle to its vas deferens.

Regions

The epididymis can be divided into three main regions
  • The head (Caput)
  • The body (Corpus)
  • The tail (Cauda)

Role in storage of sperm and ejaculation

Spermatozoa formed in the testis enter the caput epididymis, progress to the corpus, and finally reach the cauda region, where they are stored. Sperm entering the caput epididymis are incomplete - they lack the ability to swim forward (motility) and to fertilize an egg. During their transit in the epididymis, sperm undergo maturation processes necessary for them to acquire these functions. Final maturation is completed in the female reproductive tract (capacitation).
During ejaculation, sperm flow from the lower portion of the epididymis (which functions as a storage reservoir). They are packed so tightly that they are unable to swim, but are transported via the peristaltic action of muscle layers within the vas deferens, and are mixed with the diluting fluids of the seminal vesicles and other accessory glands prior to ejaculation (forming semen).
The epididymis is one of only two regions of the body to have stereocilia (the inner ear being the other.)

Pathology

An inflammation of the epididymis is called epididymitis. It is a swollen blood vessel from the testicle that appears or feels like an enlarged epididymis.

Embryology and vestigial structures

A Gartner's duct is a homologous remnant in the female.
In the embryo, the epididymis develops from tissue that once formed the mesonephros, a primitive kidney found in many aquatic vertebrates. Persistence of the cranial end of the mesonephric duct will leave behind a remnant called the appendix of the epididymis. In addition, some mesonephric tubules can persist as the paradidymis, a small body caudal to the efferent ductules.

Additional images

Image:Illu repdt male.jpg|Male reproductive system. Image:Illu testis 1b.jpg|Testis

References

External links

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epididymis in Arabic: بربخ
epididymis in Bosnian: Pasjemenik
epididymis in Bulgarian: Надсеменник
epididymis in Czech: Nadvarle
epididymis in German: Nebenhoden
epididymis in Dhivehi: މަނި ގުދަން
epididymis in Spanish: Epidídimo
epididymis in Persian: بربخ
epididymis in French: Épididyme
epididymis in Italian: Epididimo
epididymis in Latin: Epidydimis
epididymis in Lithuanian: Sėklidės prielipas
epididymis in Dutch: Bijbal
epididymis in Norwegian: Bitestikkel
epididymis in Polish: Najądrze
epididymis in Portuguese: Epidídimo
epididymis in Simple English: Epididymis
epididymis in Slovak: Nadsemenník
epididymis in Slovenian: Obmodek
epididymis in Finnish: Lisäkives
epididymis in Swedish: Bitestikel
epididymis in Chinese: 附睾
epididymis in Japanese: 精巣上体
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