Table of ContentsView AllTable of ContentsAnatomyFunctionAssociated ConditionsTests
Table of ContentsView All
View All
Table of Contents
Anatomy
Function
Associated Conditions
Tests
Theepididymisis a long, coiled tube that transports sperm from the testes to the vas deferens. The epididymis consists of three parts:
During their journey through the various parts of the epididymis, sperm mature and gain the ability to swim. Because of its role in sperm transport and maturation, functional and structural issues with the epididymis can be associated with infertility or reduced fertility.
This article will discuss the anatomy and main function of the epididymis. You’ll also learn about conditions that are related to this tubular structure.
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The epididymis is a coiled tube in three sections. It sits inside the scrotum, attached to the testes. The sperm move from the testes, through the epididymis, and into the vas deferens prior to being mixed with various secretions at the time ofejaculation.
During their time moving through the epididymis, sperm mature and gain additional function. In particular, they gain the ability to propel themselves forward. Sperm must pass through at least the middle of the corpus to mature enough to fertilize an egg on their own.However, intracytoplasmic sperm injection (ICSI) can be used to fertilize an egg with less mature sperm.
The structure of the epididymis changes along the path from the testes to the vas deferens. The walls of the tube are thickest at the head and thickness decreases along the length of the tube to the tail. As the walls get thinner, more and more water is reabsorbed into the body, and sperm concentration increases.
If uncoiled, the epididymis could be as long as 20 feet, and sperm take 10 to 15 days to travel from one end of the tube to the other.
The epididymis is divided into three segments:
Anatomical Variations
There are a number ofcongenital conditionsthat can lead to abnormalities of the epididymis. One such condition is undescended testes, orcryptorchidism, a condition where the testes are trapped in the abdomen and do not descend into the scrotum. A significant number of individuals with cryptorchidism also have abnormalities of the epididymis.
Changes in the epididymis are also associated with conditions that affect kidney development, as parts of the epididymis are derived from the same tissue as the kidneys.
Regardless of the cause, in general, there are four types of congenital anomalies seen in the epididymis.
The primary functions of the epididymis are sperm transport and sperm maturation. The epididymis serves this function across many mammalian species. As sperm travel through the epididymis they are exposed to a number of signals from the cells of the epididymis that drive their maturation.
Hundreds, or even thousands, of different genes have been identified as being expressed in the different sections of the epididymis, and many have been shown to be involved in sperm maturation in humans and other species.
There are several acquired health conditions that can affect the epididymis.
Epididymitis
Older people may also experience epididymitis related to urinary tract infections or due to conditions that cause chronic inflammation.
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Infertility Issues
Certain types of infertility may also be related to the health of the epididymis. In particular, obstructive infertility occurs when there is a blockage that prevents the passage of sperm. This blockage may be partial, in which case some sperm may get through, or complete.
Not all obstructive infertility is the result of blockages in the epididymis, but many cases are. Obstructions in the epididymis can be the result of scarring from infection, congenital abnormalities, or injuries.
Other problems with the epididymis—such as attachment issues and agenesis—can also affect fertility. Sometimes, but not always, these fertility concerns can be addressed with surgery to restore a pathway along which sperm can mature. At other times, sperm can be harvested from before the blockage and used for assisted reproduction.
It is also important to note that vasectomy can affect the health of the epididymis.Vasectomy is a surgical sterilization processthat disrupts and blocks the vas deferens so that sperm can not get into the ejaculate. In some, but not all, individuals, the process may be reversible.
Whether or not the procedure is reversible appears to be, at least in part, because of the ways in which vasectomy affects the health of the epididymis. A buildup of sperm in the epididymis after vasectomy is thought to potentially lead to damage, and there may be damage from inflammation and other immune responses, such asgranulomaformation, as well.
In general, tests of the epididymis are not performed unless an individual experiences pain in the scrotum or symptoms of infertility. If needed, the following tests are generally used:
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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
NIH: National Cancer Institute.Anatomy of the testis.Sullivan R, Mieusset R.The human epididymis: its function in sperm maturation,Hum Reprod Update. 2016;22(5):574-87. doi:10.1093/humupd/dmw015James ER, Carrell DT, Aston KI, Jenkins TG, Yeste M, Salas-Huetos A.The role of the epididymis and the contribution of epididymosomes to mammalian reproduction.IJMS. 2020;21(15):5377. doi:10.3390/ijms21155377Redshaw JD, Tran TL, Wallis MC, Devries CR.Epididymitis: a 21-year retrospective review of presentations to an outpatient urology clinic.J Urol. 2014;192(4):1203-7. doi:10.1016/j.juro.2014.04.002Frungieri MB, Calandra RS, Bartke A, Matzkin ME.Ageing and inflammation in the male reproductive tract.Andrologia. 2018;50(11):e13034. doi:10.1111/and.13034Viera AJ.Patient education: Vasectomy (Beyond the Basics).UpToDate.Mittal PK, Little B, Harri PA, et al.Role of imaging in the evaluation of male infertility.RadioGraphics. 2017;37(3):837-854. doi:10.1148/rg.2017160125MedlinePlus.Testicular biopsy.
NIH: National Cancer Institute.Anatomy of the testis.
Sullivan R, Mieusset R.The human epididymis: its function in sperm maturation,Hum Reprod Update. 2016;22(5):574-87. doi:10.1093/humupd/dmw015
James ER, Carrell DT, Aston KI, Jenkins TG, Yeste M, Salas-Huetos A.The role of the epididymis and the contribution of epididymosomes to mammalian reproduction.IJMS. 2020;21(15):5377. doi:10.3390/ijms21155377
Redshaw JD, Tran TL, Wallis MC, Devries CR.Epididymitis: a 21-year retrospective review of presentations to an outpatient urology clinic.J Urol. 2014;192(4):1203-7. doi:10.1016/j.juro.2014.04.002
Frungieri MB, Calandra RS, Bartke A, Matzkin ME.Ageing and inflammation in the male reproductive tract.Andrologia. 2018;50(11):e13034. doi:10.1111/and.13034
Viera AJ.Patient education: Vasectomy (Beyond the Basics).UpToDate.
Mittal PK, Little B, Harri PA, et al.Role of imaging in the evaluation of male infertility.RadioGraphics. 2017;37(3):837-854. doi:10.1148/rg.2017160125
MedlinePlus.Testicular biopsy.
Bedford JM.The epididymis re-visited: a personal view.Asian J Androl. 2015;17(5):693-8. doi:10.4103/1008-682X.153297
Turner TT.De Graaf’s thread: The human epididymis. J Androl. 2008;29(3):237-50. doi:10.2164/jandrol.107.004119
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