Monorchism (also monorchidism) is the state of having only one

testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...

within the

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

Terminology

An individual having monorchism can be referred to as ''monorchid''.

Causes

This can be due to: * One testicle not descending into the scrotum during normal embryonic or

fetal A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal develo ...

development (3–4% of 'normal' live births), also known as undescended testis or

cryptorchidism Cryptorchidism, also known as undescended testis, is the failure of one or both testes to descend into the scrotum. The word is from Greek () 'hidden' and () 'testicle'. It is the most common birth defect of the male genital tract. About 3% of ...

. In this case the testis is within the abdominal cavity, somewhere along the normal route of descent – most commonly, within the

inguinal canal The inguinal canals are the two passages in the anterior abdominal wall of humans and animals which in males convey the spermatic cords and in females the round ligament of the uterus. The inguinal canals are larger and more prominent in males. ...

. Such a testis has an increased risk of

malignancy Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

. * One testicle may disappear during development (the so-called

vanishing testis Anorchia (also called anorchidism or anorchism) is a disorder of sex development in which a person with XY karyotype, which corresponds to male sex, is born without testes. Within a few weeks of fertilization, the embryo develops rudimentary go ...

) due to some intrauterine insult. This is thought to be most likely

vascular The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...

, such as

testicular torsion Testicular torsion occurs when the spermatic cord (from which the testicle is suspended) twists, cutting off the blood supply to the testicle. The most common symptom in children is sudden, severe testicular pain. The testicle may be higher than ...

. * One testicle may have been surgically removed through

orchiectomy Orchiectomy (also named orchidectomy, and sometimes shortened as orchi or orchie) is a surgical procedure in which one or both testicles are removed. The surgery is performed as treatment for testicular cancer, as part of surgery for transgend ...

. * One testicle may be injured.

Notable cases

Due to testicular cancer

Lance Armstrong Lance Edward Armstrong ('' né'' Gunderson; born September 18, 1971) is an American former professional road racing cyclist. Regarded as a sports icon for winning the Tour de France seven consecutive times from 1999 to 2005 after recovering fr ...

, American bicyclist. *

Ashley Gray Ashley is a place name derived from the Old English words '' æsc'' (“ash”) and '' lēah'' (“meadow”). It may refer to: People and fictional characters * Ashley (given name), a list of people and fictional characters with the given name ...

, Ironman triathlete * Frank Church, late U.S. Senator and a presidential aspirant in 1976. His monorchism was revealed publicly during the 1976 presidential campaign. *

Tom Green Michael Thomas Green (born July 30, 1971) is a Canadian-American comedian, show host, actor, filmmaker, podcaster, and rapper. After pursuing stand-up comedy and music as a young adult, Green created and hosted ''The Tom Green Show'', which a ...

Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...

comedian-actor. *

Richard Herring Richard Keith Herring (born 12 July 1967) is an English stand-up comedian and writer, whose early work includes the comedy double act Lee and Herring (alongside Stewart Lee). He is described by ''The British Theatre Guide'' as "one of the lead ...

, English comedian and writer *

John Kruk John Martin Kruk (born February 9, 1961) is an American former professional baseball first baseman and outfielder. Kruk played in Major League Baseball (MLB) for the San Diego Padres, Philadelphia Phillies, and Chicago White Sox from through . Du ...

, former baseball player *

Mark Latham Mark William Latham (born 28 February 1961) is an Australian politician and media commentator, currently serving as a member in the New South Wales Legislative Council. He previously served as the leader of the Australian Labor Party (ALP) and ...

, former Australian politician. *

Geoff Horsfield Geoffrey Malcolm Horsfield (born 1 November 1973) is an English former professional footballer and football coach. He made more than 300 appearances in the Football League playing as a striker. He was a "strong and forceful" player, able to h ...

, English footballer. *

Nenê Nenê (; born Maybyner Rodney Hilário; September 13, 1982) is a Brazilian former professional basketball player. Known previously as Nenê Hilario, he legally changed his name to simply Nenê in 2003. Early life Born Maybyner Rodney Hilário i ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

ian basketball player. *

Kevin Curtis Kevin Devon Curtis (born July 17, 1978) is a former American football wide receiver in the National Football League (NFL). He played college football at Utah State and was drafted by the St. Louis Rams in the third round of the 2003 NFL Draft. ...

, American football player. *

Nigel Farage Nigel Paul Farage (; born 3 April 1964) is a British broadcaster and former politician who was Leader of the UK Independence Party (UKIP) from 2006 to 2009 and 2010 to 2016 and Leader of the Brexit Party (renamed Reform UK in 2021) from 2 ...

, former leader of the

UK Independence Party The UK Independence Party (UKIP; ) is a Eurosceptic, right-wing populist political party in the United Kingdom. The party reached its greatest level of success in the mid-2010s, when it gained two members of Parliament and was the largest par ...

. * Bobby Moore, English footballer and World Cup winner. *

Jimmy White James Warren White (born 2 May 1962) is an English professional snooker player who has won three seniors World titles. Nicknamed "The Whirlwind" because of his fluid, attacking style of play, White is the 1980 World Amateur Champion, 2009 ...

, English snooker player.

Due to injury

* Archibald Douglas, 4th Earl of Douglas, magnate of the Kingdom of Scotland, and Peer of France. Lost in 1403, while fighting at the Battle of Shrewsbury (The previous year he had lost an eye at the Battle of Homildon Hill). *

Troy Bayliss Troy Bayliss (born 30 March 1969 in Taree, New South Wales, Australia) is an Australian motorcycle racer. During his career Bayliss won the Superbike World Championship three times and a MotoGP race, all with Ducati. He finished his career aft ...

, world

superbike A sport bike (sports motorcycle, or sports bike) is a motorcycle designed and optimized for speed, acceleration, braking, and cornering on asphalt concrete race tracks and roads. They are mainly designed for performance at the expense of comfor ...

champion in 2001, 2006 and 2008. In 2007 he lost a testicle during a race at Donington Park. * Brian Foster, American mixed martial artist. * John Starks, American basketball player. * Paul Wood, English

rugby league Rugby league football, commonly known as just rugby league and sometimes football, footy, rugby or league, is a full-contact sport played by two teams of thirteen players on a rectangular field measuring 68 metres (75 yards) wide and 11 ...

player who sustained a ruptured testicle during a match and subsequently had it removed. *

Thurgood Marshall Thurgood Marshall (July 2, 1908 – January 24, 1993) was an American civil rights lawyer and jurist who served as an associate justice of the Supreme Court of the United States from 1967 until 1991. He was the Supreme Court's first African-A ...

, United States Supreme Court Justice who injured a testicle during a fraternity event in university. * Tom Lamping, United Kingdom, injured a testicle during a dog fight gone wrong. * Porvali Robert, Grandson of Seppo Porvali and nephew of Finnish author Mikko Porvali, injured his testicle whilst downhill skiing in

Ylläs Ylläs, or Yllästunturi in Finnish, is a high fell in the municipality of Kolari in Lapland Province of Finland. There are two villages near Ylläs: Äkäslompolo on the north side and Ylläsjärvi in the south. They are connected by an 11&n ...

Due to cryptorchidism

Mao Zedong Mao Zedong pronounced ; also romanised traditionally as Mao Tse-tung. (26 December 1893 – 9 September 1976), also known as Chairman Mao, was a Chinese communist revolutionary who was the founder of the People's Republic of China (PRC) ...

, founder of the People's Republic of China.

Unknown

* Possible monorchism of Adolf Hitler * Francisco Franco, caudillo of Spain.

Monorchism in nonhuman animals

Although extremely rare, monorchism has been observed to be characteristic of some animal species, notably in beetles.

References

{{Male congenital malformations of genital organs, indeterminate sex and pseudohermaphroditism