Editing Virilization

{{Short description|Biological development of male sex characteristics}}
{{Sex (biology) sidebar}}{{More citations needed|date=July 2023}}
'''Virilization''' or '''masculinization'''<!-- NOTE: The term "masculinization" redirects here. Because of this, and WP:Alternative title, the term should be bolded and mentioned in the lead. --> is the biological development of adult male characteristics in young males or females.<ref>{{Cite web|url=https://www.collinsdictionary.com/dictionary/english/virilization|title=Virilization definition and meaning {{!}} Collins English Dictionary|website=www.collinsdictionary.com|language=en|access-date=2017-11-26}}</ref> Most of the changes of virilization are produced by [[androgen]]s.

Virilization is a medical [[terminology|term]] commonly used in three medical and [[Sex differences in humans|biology of sex]] contexts: prenatal biological [[sexual differentiation]], the postnatal changes of typical chromosomal male (46, XY) [[puberty]], and excessive androgen effects in typical chromosomal females (46, XX). It is also the intended result of [[androgen replacement therapy]] in males with [[delayed puberty]] and [[low testosterone]].

==Prenatal virilization==
In the prenatal period, virilization refers to closure of the [[perineum]], thinning and wrinkling (rugation) of the [[scrotum]], growth of the penis, and closure of the [[urethral groove]] to the tip of the [[penis]]. In this context, ''masculinization'' is synonymous with ''virilization''.

Prenatal virilization of XX fetuses and undervirilization of XY fetuses are common causes of [[ambiguous genitalia]] such as in conditions like [[Congenital adrenal hyperplasia]] and [[5α-Reductase 2 deficiency]].

For many years, it was widely believed that in [[mammals]], the female is the "default" developmental pathway, and the [[Sex-determining region Y protein|SRY gene]] on the [[Y chromosome]] is responsible for suppressing the development of female characteristics and stimulating males characteristics. In this scenario, an [[embryo]] would passively develop female sexual characteristics without intervention by the SRY gene. However, in the early 2000s, other genes, such as [[WNT4]] and [[R-spondin 1|RSPO1]], were discovered that perform the opposite function  – i.e., genes which suppress masculinization and stimulate feminization.<ref>{{Cite journal |last=Ainsworth |first=Claire |date=February 2015 |title=Sex redefined |journal=Nature |language=en |volume=518 |issue=7539 |pages=288–291 |doi=10.1038/518288a |pmid=25693544 |bibcode=2015Natur.518..288A |issn=0028-0836|doi-access=free }}</ref>

Two processes: [[defeminization]], and masculinization, are involved in producing [[male]] typical morphology and behavior.

===High===
Prenatal virilization of a genetically female fetus can occur when an excessive amount of androgen is produced by the fetal [[adrenal gland]]s or is present in maternal blood, resulting in virilization of the female genitalia such as an [[Clitoromegaly|enlarged clitoris.]]

It can also be associated with [[progestin-induced virilisation]].

===Low===
''Undervirilization'' can occur if a genetic male cannot produce enough androgen or the body tissues cannot respond to it. Extreme undervirilization occurs when no significant androgen hormones can be produced or the body is completely insensitive to androgens, in which case a female phenotype will develop. Partial undervirilization produces ambiguous genitalia part-way between male and female. Examples of undervirilization in fetuses with a 46,XY karyotype are [[androgen insensitivity syndrome]] and [[5 alpha reductase deficiency]].

==Normal virilization==
{{See also|Puberty#Changes in males}}
In common as well as medical usage, virilization often refers to the process of normal male [[puberty]]. These effects include growth of the penis and the testes, accelerated growth, [[Pubarche|development of pubic hair]], and other androgenic hair of face, torso, and limbs, [[Voice change|deepening of the voice]], increased musculature, thickening of the jaw, prominence of the neck cartilage, and broadening of the shoulders.

==Abnormal childhood virilization==
Virilization can occur in childhood in both males and females due to excessive amounts of androgens. Typical effects of virilization in children are [[pubic hair]], accelerated growth and bone maturation, increased [[muscle strength]], [[Acne vulgaris|acne]], and adult body odor. In males, virilization may signal [[precocious puberty]], while [[congenital adrenal hyperplasia]] and androgen producing tumors (usually) of the [[gonad]]s or adrenals are occasional causes in both sexes.<ref>{{Cite web|title=Virilization: MedlinePlus Medical Encyclopedia|url=https://medlineplus.gov/ency/article/002339.htm|access-date=2020-10-23|website=medlineplus.gov|language=en}}</ref>

==In adolescent or adult females==
Virilization in females can manifest as [[clitoris|clitoral]] enlargement, increased muscle strength, acne, [[hirsutism]], frontal hair thinning, deepening of the voice, [[menstrual period|menstrual]] disruption due to [[anovulation]], and a strengthened libido.<ref>{{cite book|title=Women's Gynecologic Health|first1=Kerri Durnell |last1=Schuiling|first2= Frances E.|last2= Likis|publisher=Jones & Bartlett Publishers|year= 2005|isbn=978-0-7637-4717-6}}</ref> Some of the possible causes of virilization in females are:
* [[Androgen]]-producing tumors of the
** [[ovary|ovaries]]
** [[adrenal gland]]s (see [[adrenal tumor]])
** [[pituitary gland]] (see [[pituitary adenoma]])
* [[Hyperthecosis]]
* [[Hypothyroidism]]
* [[Anabolic steroid]] exposure
* [[Congenital adrenal hyperplasia due to 21-hydroxylase deficiency]] (late-onset)
* [[Conn's syndrome]]

== Medically induced virilization in transgender people ==
{{See also|Masculinizing hormone therapy}}

Transgender people who were medically assigned female at birth sometimes elect to take [[Hormone replacement therapy (female-to-male)|hormone replacement therapy]]. This process causes virilization by inducing many of the effects of a typically male puberty. Many of these effects are permanent, but some effects can be reversed if the transgender individual stops or pauses their medical treatment.

=== Permanent virilization effects ===
* Deepening of the voice
* Growth of facial and body hair
* Male-pattern [[baldness]]
* Enlargement of the [[clitoris]]
* [[Breast atrophy]] – possible shrinking and/or softening of breasts

=== Reversible virilization effects ===
* Further muscle development (especially upper body)
* Increased sweat and changes in body odor
* Prominence of veins and coarser skin
* Alterations in blood lipids ([[cholesterol]] and [[triglycerides]])
* Increased red blood cell count

==Demasculinization==
Demasculinization refers to the reversal of virilization. Some but not all aspects of virilization are reversible. Demasculinization occurs naturally with [[andropause]], pathologically with [[hypogonadism]], and artificially or medically with [[antiandrogen]]s, [[estrogen (medication)|estrogen]]s, and [[orchiectomy]]. It is desired by many [[transgender hormone therapy (male-to-female)|transgender women]] who have undergone the changes of pubertal masculinization. Some virilized traits remain though (such as body hair, a hard [[jaw]]line and an enlarged [[larynx]]), due to the fashion in which virilization affects a body's physiology.

== See also ==
* [[Ambiguous genitalia]]
* [[Androgen]]
* [[Clitoromegaly]]
* [[Defeminization]]
* [[Feminization (biology)]]
* [[Hirsutism]]
* [[Secondary sex characteristic]]s
* [[Sexual differentiation]]
* [[Transient masculinization]]

==References==
{{reflist}}

==Further reading==
* Howell, W. M., Black, D. A., & Bortone, S. A. (1980). ''[https://www.researchgate.net/profile/Stephen_Bortone/publication/271792093_Abnormal_Expression_of_Secondary_Sex_Characters_in_a_Population_of_Mosquitofish_Gambusia_affinis_holbrooki_Evidence_for_Environmentally-Induced_Masculinization/links/56e9719a08ae77f87278ff34/Abnormal-Expression-of-Secondary-Sex-Characters-in-a-Population-of-Mosquitofish-Gambusia-affinis-holbrooki-Evidence-for-Environmentally-Induced-Masculinization.pdf Abnormal expression of secondary sex characters in a population of mosquitofish, Gambusia affinis holbrooki: evidence for environmentally-induced masculinization].'' Copeia, 676–681.

==External links==
{{wiktionary|virilization}}

{{Reproductive physiology}}

[[Category:Sexual dimorphism]]
[[Category:Metabolism]]
[[Category:Physiology]]
[[Category:Testosterone]]