Editing Vagina (section)

==Structure==
===Gross anatomy===
{{See also|Vaginal support structures}}
[[File:Blausen 0400 FemaleReproSystem 02b.png|thumb|upright=1.36|alt=Diagram illustrating female pelvic anatomy|Pelvic anatomy including organs of the female reproductive system]]

The human vagina is an elastic, muscular canal that extends from the vulva to the cervix.<ref name="Snell">{{cite book|vauthors=Snell RS|title=Clinical Anatomy: An Illustrated Review with Questions and Explanations|url=https://books.google.com/books?id=5s7jDVQkCfoC&pg=PA98|year=2004|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-4316-7|page=98|access-date=October 27, 2015|archive-date=March 10, 2021|archive-url=https://web.archive.org/web/20210310000538/https://books.google.com/books?id=5s7jDVQkCfoC&pg=PA98|url-status=live}}</ref><ref name="Dutta">{{cite book|vauthors=Dutta DC|title=DC Dutta's Textbook of Gynecology|year=2014|publisher=JP Medical Ltd|isbn=978-93-5152-068-9|pages=2–7|url=https://books.google.com/books?id=40yVAwAAQBAJ&pg=PA2|access-date=October 27, 2015|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704043225/https://books.google.com/books?id=40yVAwAAQBAJ&pg=PA2|url-status=live}}</ref> The opening of the vagina lies in the [[urogenital triangle]]. The urogenital triangle is the front triangle of the [[perineum]] and also consists of the urethral opening and associated parts of the external genitalia.<ref name="Drake">{{cite book|vauthors=Drake R, Vogl AW, Mitchell A|title=Gray's Basic Anatomy E-Book|year=2016|publisher=[[Elsevier Health Sciences]]|isbn=978-0-323-50850-6|page=246|url=https://books.google.com/books?id=fojKDQAAQBAJ&pg=PA246|access-date=May 25, 2018|archive-date=June 4, 2021|archive-url=https://web.archive.org/web/20210604234718/https://books.google.com/books?id=fojKDQAAQBAJ&pg=PA246|url-status=live}}</ref> The '''vaginal canal''' travels upwards and backwards, between the urethra at the front, and the rectum at the back. Near the upper vagina, the cervix protrudes into the vagina on its front surface at approximately a 90 degree angle.<ref name="Mulhall">{{cite book |vauthors=Ginger VA, Yang CC |chapter=Functional Anatomy of the Female Sex Organs |veditors=Mulhall JP, Incrocci L, Goldstein I, Rosen R |title=Cancer and Sexual Health |isbn=978-1-60761-915-4 |publisher=[[Springer Publishing|Springer]] |year=2011 |pages=13, 20–21 |chapter-url=https://books.google.com/books?id=GpIadil3YsQC&pg=PA13 |access-date=August 20, 2020 |archive-date=December 16, 2019 |archive-url=https://web.archive.org/web/20191216021705/https://books.google.com/books?id=GpIadil3YsQC&pg=PA13 |url-status=live }}</ref> The vaginal and urethral openings are protected by the labia.<ref name="Kinetics2009">{{cite book|vauthors=Ransons A|chapter=Reproductive Choices|title=Health and Wellness for Life|chapter-url=https://books.google.com/books?id=2GZ7N4wOeGYC&pg=PA221|date=May 15, 2009|publisher=Human Kinetics 10%|isbn=978-0-7360-6850-5|page=221|access-date=October 27, 2015|archive-date=May 6, 2016|archive-url=https://web.archive.org/web/20160506004528/https://books.google.com/books?id=2GZ7N4wOeGYC&pg=PA221|url-status=live}}</ref>

When not [[sexually aroused]], the vagina is a collapsed tube, with the front and back walls placed together. The lateral walls, especially their middle area, are relatively more rigid. Because of this, the collapsed vagina has an H-shaped cross section.<ref name="Dutta"/><ref name="Beckmann 2">{{cite book|vauthors=Beckmann CR|title=Obstetrics and Gynecology|publisher=[[Lippincott Williams & Wilkins]]|isbn=978-0-7817-8807-6|page=37|year=2010|url=https://books.google.com/books?id=0flWgd3OJLEC&pg=PA37|quote=Because the vagina is collapsed, it appears H-shaped in cross section.|access-date=January 31, 2017|archive-date=February 15, 2017|archive-url=https://web.archive.org/web/20170215191755/https://books.google.com/books?id=0flWgd3OJLEC&pg=PA37|url-status=live}}</ref> Behind, the upper vagina is separated from the [[rectum]] by the [[recto-uterine pouch]], the middle vagina by loose [[connective tissue]], and the lower vagina by the [[Perineum#Body|perineal body]].<ref name=GRAYS2008>{{cite book |veditors=Standring S, Borley NR |title=Gray's anatomy : the anatomical basis of clinical practice|date=2008|publisher=Churchill Livingstone|location=London|isbn=978-0-8089-2371-8|edition=40th|pages=1281–4}}</ref> Where the vaginal [[Lumen (anatomy)|lumen]] surrounds the cervix of the uterus, it is divided into four continuous regions ([[vaginal fornices]]); these are the anterior, posterior, right lateral, and left lateral fornices.<ref name="Snell"/><ref name="Dutta"/> The posterior fornix is deeper than the anterior fornix.<ref name="Dutta"/>

Supporting the vagina are its upper, middle, and lower third muscles and ligaments. The upper third are the [[levator ani]] muscles, and the transcervical, [[Pubocervical ligament|pubocervical]], and sacrocervical ligaments.<ref name="Snell"/><ref name="Baggish">{{cite book|vauthors=Baggish MS, Karram MM|title=Atlas of Pelvic Anatomy and Gynecologic Surgery - E-Book|year=2011|page=582|publisher=[[Elsevier Health Sciences]]|isbn=978-1-4557-1068-3|url=https://books.google.com/books?id=lwWldKFVPYYC&pg=PA582|access-date=May 7, 2018|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704043154/https://books.google.com/books?id=lwWldKFVPYYC&pg=PA582|url-status=live}}</ref> It is supported by the upper portions of the [[cardinal ligament]]s and the [[parametrium]].<ref name="Arulkumaran 1">{{cite book|vauthors=Arulkumaran S, Regan L, Papageorghiou A, Monga A, Farquharson D|title=Oxford Desk Reference: Obstetrics and Gynaecology|year=2011|page=472|publisher=[[OUP Oxford]]|isbn=978-0-19-162087-4|url=https://books.google.com/books?id=lRaWcRYx_7YC&pg=PA472|access-date=May 7, 2018|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703220025/https://books.google.com/books?id=lRaWcRYx_7YC&pg=PA472|url-status=live}}</ref> The middle third of the vagina involves the [[urogenital diaphragm]].<ref name="Snell"/> It is supported by the levator ani muscles and the lower portion of the cardinal ligaments.<ref name="Arulkumaran 1"/> The lower third is supported by the perineal body,<ref name="Snell"/><ref name="Elsevier Obstetrics">{{Cite book |title=Manual of Obstetrics |edition =3rd |publisher=[[Elsevier]] |year=2011 |pages=1–16 |isbn=978-81-312-2556-1}}</ref> or the urogenital and [[pelvic diaphragm]]s.<ref name="Smith 2">{{cite book|vauthors=Smith RP, Turek P|title=Netter Collection of Medical Illustrations: Reproductive System E-Book|year=2011|page=443|publisher=[[Elsevier Health Sciences]]|isbn=978-1-4377-3648-9|url=https://books.google.com/books?id=ySriOOirL_UC&pg=PT443|access-date=May 7, 2018|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703211240/https://books.google.com/books?id=ySriOOirL_UC&pg=PT443|url-status=live}}</ref> The lower third may also be described as being supported by the perineal body and the pubovaginal part of the levator ani muscle.<ref name="Baggish"/>

====Vaginal opening and hymen====
[[File:Vaginal opening description-en.svg|A human vulva with vaginal opening labeled|thumb]]
The '''vaginal opening''' (also known as the '''vaginal introitus''' and the Latin '''''ostium vaginae''''')<ref>{{cite book|last1=Ricci|first1=Susan Scott|last2=Kyle|first2=Terri|publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins|year = 2009|title=Maternity and Pediatric Nursing|page=77|access-date=January 7, 2024|isbn=978-0-78178-055-1|url=https://books.google.com/books?id=gaYtFuND7VIC&pg=PA77}}</ref><ref>{{cite book|last=Zink|first=Christopher|publisher=De Gruyter|year = 2011|title= Dictionary of Obstetrics and Gynecology |page=174|isbn= 978-3-11085-727-6 |url= https://books.google.com/books?id=EQlvzV9V7xIC&pg=PA174}}</ref> is at the posterior end of the [[vulval vestibule]], behind the [[urinary meatus|urethral opening]]. The term ''introitus'' is more technically correct than "opening", since the vagina is usually collapsed, with the opening closed. The opening to the vagina is normally obscured by the [[labia minora]] (inner lips), but may be exposed after [[vaginal delivery]].<ref name="Dutta"/>

The [[hymen]] is a thin layer of [[mucous membrane|mucosal tissue]] that surrounds or partially covers the vaginal opening.<ref name="Dutta"/> The effects of [[sexual intercourse|intercourse]] and childbirth on the hymen vary. Where it is broken, it may completely disappear or remnants known as ''carunculae myrtiformes'' may persist. Otherwise, being very elastic, it may return to its normal position.<ref name="Knight">{{cite book|vauthors=Knight B |title=Simpson's Forensic Medicine|edition=11th|year=1997|publisher=Arnold|location=London|page=114|isbn=978-0-7131-4452-9}}</ref> Additionally, the hymen may be lacerated by disease, injury, [[medical examination]], [[masturbation]] or [[physical exercise]]. For these reasons, [[virginity]] cannot be definitively determined by examining the hymen.<ref name="Knight"/><ref name="Perlman">{{Cite book|vauthors=Perlman SE, Nakajyma ST, Hertweck SP |title=Clinical protocols in pediatric and adolescent gynecology|year=2004|publisher=Parthenon |page=131 |isbn=978-1-84214-199-1 }}</ref>

====Variations and size====
{{Main|Human vaginal size}}
The length of the vagina [[anatomical variation|varies]] among women of child-bearing age. Because of the presence of the cervix in the front wall of the vagina, there is a difference in length between the front wall, approximately 7.5&nbsp;cm (2.5 to 3 in) long, and the back wall, approximately 9&nbsp;cm (3.5&nbsp;in) long.<ref name="Dutta"/><ref name="Wylie"/>  During sexual arousal, the vagina expands both in length and width. If a woman stands upright, the vaginal canal points in an upward-backward direction and forms an angle of approximately 45 degrees with the uterus.<ref name="Dutta"/><ref name="Elsevier Obstetrics"/> The vaginal opening and hymen also vary in size; in children, although the hymen commonly appears [[crescent]]-shaped, many shapes are possible.<ref name="Dutta"/><ref name="Emans">{{cite book|vauthors=Emans SJ|chapter=Physical Examination of the Child and Adolescent|title=Evaluation of the Sexually Abused Child: A Medical Textbook and Photographic Atlas|edition=2nd|publisher=[[Oxford University Press]]|pages=61–65|isbn=978-0-19-974782-5|date=2000|chapter-url=https://books.google.com/books?id=3eQZhs4PwrYC|access-date=August 2, 2015|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704044740/https://books.google.com/books?id=3eQZhs4PwrYC|url-status=live}}</ref>

===Development===
{{Further|Development of the reproductive system}}
[[File:Sobo 1906 508.png|right|thumb|alt=Drawn anatomic illustration as described in caption|An illustration showing a cut-away portion of the vagina and upper female genital tract (only one ovary and fallopian tube shown). Circular folds (also called rugae) of vaginal mucosa can be seen.]]
The vaginal plate is the precursor to the vagina.<ref name="Edmonds" /> During development, the vaginal plate begins to grow where the fused ends of the [[paramesonephric duct]]s (Müllerian ducts) enter the back wall of the [[urogenital sinus]] as the [[sinus tubercle]]. As the plate grows, it significantly separates the cervix and the urogenital sinus; eventually, the central cells of the plate break down to form the vaginal [[Lumen (anatomy)|lumen]].<ref name="Edmonds">{{cite book|vauthors=Edmonds K|title=Dewhurst's Textbook of Obstetrics and Gynaecology|publisher=[[John Wiley & Sons]]|isbn=978-0-470-65457-6|year=2012|page=423|url=https://books.google.com/books?id=HfakBRceodcC&pg=PA423|access-date=October 27, 2015|archive-date=May 6, 2016|archive-url=https://web.archive.org/web/20160506172501/https://books.google.com/books?id=HfakBRceodcC&pg=PA423|url-status=live}}</ref> This usually occurs by the twenty to twenty-fourth week of development. If the lumen does not form, or is incomplete, membranes known as [[vaginal septum|vaginal septa]] can form across or around the tract, causing obstruction of the outflow tract later in life.<ref name="Edmonds"/>

There are conflicting views on the embryologic origin of the vagina. The majority view is Koff's 1933 description, which posits that the upper two-thirds of the vagina originate from the caudal part of the Müllerian duct, while the lower part of the vagina develops from the urogenital sinus.<ref name="Herrington">{{cite book|vauthors=Herrington CS|title=Pathology of the Cervix|publisher=[[Springer Science & Business Media]]|isbn=978-3-319-51257-0|year=2017|pages=2–3|url=https://books.google.com/books?id=hc40DwAAQBAJ&pg=PA2|access-date=March 21, 2018|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703211425/https://books.google.com/books?id=hc40DwAAQBAJ&pg=PA2|url-status=live}}</ref><ref name="Woodruff">{{cite book|vauthors=Woodruff TJ, Janssen SJ, Guillette LJ, Jr, Giudice LC|title=Environmental Impacts on Reproductive Health and Fertility|publisher=[[Cambridge University Press]]|isbn=978-1-139-48484-8|year=2010|page=33|url=https://books.google.com/books?id=WQRAfsjuUgQC&pg=PA33|access-date=March 21, 2018|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703211348/https://books.google.com/books?id=WQRAfsjuUgQC&pg=PA33|url-status=live}}</ref> Other views are Bulmer's 1957 description that the vaginal epithelium derives solely from the urogenital sinus epithelium,<ref name="New insights"/> and Witschi's 1970 research, which reexamined Koff's description and concluded that the [[sinovaginal bulb]]s are the same as the lower portions of the [[Wolffian duct]]s.<ref name="Woodruff"/><ref name="Grigoris">{{cite book|vauthors=Grimbizis GF, Campo R, Tarlatzis BC, Gordts S|title=Female Genital Tract Congenital Malformations: Classification, Diagnosis and Management|publisher=[[Springer Science & Business Media]]|isbn=978-1-4471-5146-3|year=2015|page=8|url=https://books.google.com/books?id=IGlnBgAAQBAJ&pg=PA8|access-date=March 21, 2018|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703211446/https://books.google.com/books?id=IGlnBgAAQBAJ&pg=PA8|url-status=live}}</ref> Witschi's view is supported by research by Acién et al., Bok and Drews.<ref name="Woodruff"/><ref name="Grigoris"/> Robboy et al. reviewed Koff and Bulmer's theories, and support Bulmer's description in light of their own research.<ref name="New insights"/> The debates stem from the complexity of the interrelated tissues and the absence of an animal model that matches human vaginal development.<ref name="New insights">{{cite journal |vauthors=Robboy S, Kurita T, Baskin L, Cunha GR |year=2017 |title=New insights into human female reproductive tract development |pmid=28918284|pmc=5712241 |journal=Differentiation |volume= 97|pages=9–22|doi=10.1016/j.diff.2017.08.002|issn=0301-4681 }}</ref><ref name="Kurman">{{cite book|vauthors=Kurman RJ|title=Blaustein's Pathology of the Female Genital Tract|publisher=[[Springer Science & Business Media]]|isbn=978-1-4757-3889-6|year=2013|page=132|url=https://books.google.com/books?id=sM3eBwAAQBAJ&pg=PA132|access-date=March 21, 2018|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704043223/https://books.google.com/books?id=sM3eBwAAQBAJ&pg=PA132|url-status=live}}</ref> Because of this, study of human vaginal development is ongoing and may help resolve the conflicting data.<ref name="Woodruff"/>

===Microanatomy===
{{Main|Vaginal epithelium}}
[[File:Vagina (mucosa).JPG|thumb|alt=Micrograph of vaginal wall|Medium-power magnification [[micrograph]] of a [[H&E stain]]ed slide showing a portion of a vaginal wall. [[Stratified squamous epithelium]] and underling connective tissue can be seen. The deeper muscular layers are not shown. The black line points to a fold in the mucosa.]]
The '''vaginal wall''' from the lumen outwards consists firstly of a [[mucosa]] of [[stratified squamous epithelium]] that is not [[Stratified squamous epithelium#Keratinized|keratinized]], with a [[lamina propria]] (a thin layer of [[connective tissue]]) underneath it. Secondly, there is a layer of [[smooth muscle]] with bundles of circular fibers internal to longitudinal fibers (those that run lengthwise). Lastly, is an outer layer of connective tissue called the [[adventitia]]. Some texts list four layers by counting the two sublayers of the mucosa (epithelium and lamina propria) separately.<ref name="Brown">{{cite book|vauthors=Brown L|title=Pathology of the Vulva and Vagina|year=2012|publisher=[[Springer Science+Business Media]]|isbn=978-0-85729-757-0|pages=6–7|url=https://books.google.com/books?id=Yv2CMHoVR9wC&pg=PA6|access-date=October 27, 2015|archive-date=April 25, 2016|archive-url=https://web.archive.org/web/20160425014619/https://books.google.com/books?id=Yv2CMHoVR9wC&pg=PA6|url-status=live}}</ref><ref name="Arulkumaran">{{cite book|vauthors=Arulkumaran S, Regan L, Papageorghiou A, Monga A, Farquharson D|title=Oxford Desk Reference: Obstetrics and Gynaecology|year=2011|publisher=[[Oxford University Press]]|isbn=978-0-19-162087-4|page=471|url=https://books.google.com/books?id=lRaWcRYx_7YC&pg=PA471|access-date=October 27, 2015|archive-date=May 6, 2016|archive-url=https://web.archive.org/web/20160506160720/https://books.google.com/books?id=lRaWcRYx_7YC&pg=PA471|url-status=live}}</ref>

The smooth [[muscular layer]] within the vagina has a weak contractive force that can create some pressure in the lumen of the vagina. Much stronger contractive force, such as during childbirth, comes from muscles in the [[pelvic floor]] that are attached to the adventitia around the vagina.<ref name=Bitzer>{{cite book|vauthors=Bitzer J, Lipshultz L, Pastuszak A, Goldstein A, Giraldi A, Perelman M |title=Management of Sexual Dysfunction in Men and Women |date=2016 |publisher=Springer New York |isbn=978-1-4939-3099-9 |page=202 |language=en |chapter=The Female Sexual Response: Anatomy and Physiology of Sexual Desire, Arousal, and Orgasm in Women|doi=10.1007/978-1-4939-3100-2_18 }}</ref>

The lamina propria is rich in blood vessels and lymphatic channels. The muscular layer is composed of smooth muscle fibers, with an outer layer of longitudinal muscle, an inner layer of circular muscle, and oblique muscle fibers between. The outer layer, the adventitia, is a thin dense layer of connective tissue and it blends with loose connective tissue containing blood vessels, [[lymphatic vessel]]s and nerve fibers that are between pelvic organs.<ref name="Mulhall" /><ref name="Arulkumaran" /><ref name="Wylie">{{cite book|vauthors=Wylie L|title=Essential Anatomy and Physiology in Maternity Care|year=2005|publisher=Elsevier Health Sciences|isbn=978-0-443-10041-3|pages=157–158|url=https://books.google.com/books?id=QgpOvSDxGGYC&pg=PA157|access-date=October 27, 2015|archive-date=May 5, 2016|archive-url=https://web.archive.org/web/20160505063932/https://books.google.com/books?id=QgpOvSDxGGYC&pg=PA157|url-status=live}}</ref> The vaginal mucosa is absent of glands. It forms folds (transverse ridges or [[rugae]]), which are more prominent in the outer third of the vagina; their function is to provide the vagina with increased surface area for extension and stretching.<ref name="Snell"/><ref name="Dutta"/>

[[File:Rugae vaginales.jpg|thumb|alt=Close-up photograph of vagina|Folds of mucosa (or [[vaginal rugae]]) are shown in the front third of a vagina.]]
The epithelium of the ectocervix (the portion of the uterine cervix extending into the vagina) is an extension of, and shares a border with, the vaginal epithelium.<ref name="Junctions">{{cite journal|vauthors=Blaskewicz CD, Pudney J, Anderson DJ |title=Structure and function of intercellular junctions in human cervical and vaginal mucosal epithelia.|journal=Biology of Reproduction|date=July 2011|volume=85|issue=1|pages=97–104|doi=10.1095/biolreprod.110.090423|pmid=21471299|pmc=3123383}}</ref>  The vaginal epithelium is made up of layers of cells, including the [[Stratum basale|basal cells]], the parabasal cells, the superficial [[squamous cell|squamous flat cells]], and the intermediate cells.<ref name="Mayeaux">{{cite book|title=Modern Colposcopy Textbook and Atlas |vauthors=Mayeaux EJ, Cox JT |publisher=[[Lippincott Williams & Wilkins]]|year=2011|isbn=978-1-4511-5383-5|url=https://books.google.com/books?id=3lEtAxpNLewC&pg=SA2-PA29-IA2}}</ref> The basal layer of the epithelium is the most mitotically active and reproduces new cells.<ref name="Blaustein2002">{{cite book|url=https://books.google.com/books?id=tuKGMxGRKa8C|title=Blaustein's Pathology of the Female Genital Tract|publisher=Springer|year=2002|veditors=Kurman RJ|edition=5th|page=154|isbn=978-0-387-95203-1|access-date=October 27, 2015|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703220003/https://books.google.com/books?id=tuKGMxGRKa8C|url-status=live}}</ref> The superficial cells [[desquamation|shed]] continuously and basal cells replace them.<ref name="Dutta"/><ref name="Beckmann"/><ref name="Robboy">{{cite book|url=https://books.google.com/books?id=ab545XL-MBEC&pg=PA111|title=Robboy's Pathology of the Female Reproductive Tract|vauthors=Robboy SJ|publisher=[[Elsevier Health Sciences]]|year=2009|isbn=978-0-443-07477-6|page=111|access-date=December 15, 2017|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704043208/https://books.google.com/books?id=ab545XL-MBEC&pg=PA111|url-status=live}}</ref> [[Estrogen]] induces the intermediate and superficial cells to fill with [[glycogen]].<ref name="Robboy" /><ref>{{Cite journal |vauthors=Nunn KL, Forney LJ |date=September 2016 |title=Unraveling the Dynamics of the Human Vaginal Microbiome |journal=The Yale Journal of Biology and Medicine|volume=89|issue=3|pages=331–337|issn=0044-0086|pmc=5045142|pmid=27698617}}</ref> Cells from the lower basal layer transition from active metabolic activity to death ([[apoptosis]]). In these mid-layers of the epithelia, the cells begin to lose their [[mitochondria]] and other [[organelle]]s.<ref name="Blaustein2002"/><ref>{{cite book|title=Reproductive and developmental toxicology|vauthors=Gupta R |publisher=Academic Press|year=2011|isbn=978-0-12-382032-7|location=London|pages=1005}}</ref> The cells retain a usually high level of glycogen compared to other epithelial tissue in the body.<ref name="Blaustein2002" />

Under the influence of maternal estrogen, the vagina of a newborn is lined by thick stratified squamous epithelium (or mucosa) for two to four weeks after birth. Between then to [[puberty]], the epithelium remains thin with only a few layers of cuboidal cells without glycogen.<ref name="Robboy"/><ref name="G and H">{{cite book|vauthors=Hall J |title=Guyton and Hall textbook of medical physiology|date=2011|publisher=Saunders/Elsevier|location=Philadelphia |isbn=978-1-4160-4574-8|page=993|edition=12th}}</ref>  The epithelium also has few rugae and is red in color before puberty.<ref name="Dalton" /> When puberty begins, the mucosa thickens and again becomes stratified squamous epithelium with glycogen containing cells, under the influence of the girl's rising estrogen levels.<ref name="Robboy"/> Finally, the epithelium thins out from [[menopause]] onward and eventually ceases to contain glycogen, because of the lack of estrogen.<ref name="Dutta"/><ref name="Beckmann">{{cite book|vauthors=Beckmann CR|title=Obstetrics and Gynecology|publisher=[[Lippincott Williams & Wilkins]]|isbn=978-0-7817-8807-6|pages=241–245|year=2010|url=https://books.google.com/books?id=0flWgd3OJLEC&pg=PA241|access-date=October 27, 2015|archive-date=July 3, 2019|archive-url=https://web.archive.org/web/20190703211259/https://books.google.com/books?id=0flWgd3OJLEC&pg=PA241|url-status=live}}</ref><ref name="Gad">{{cite book|vauthors=Gad SC|title=Pharmaceutical Manufacturing Handbook: Production and Processes|publisher=[[John Wiley & Sons]]|isbn=978-0-470-25980-1|page=817|year=2008|url=https://books.google.com/books?id=4c0Hp3AOi8UC&pg=PA817|access-date=October 27, 2015|archive-date=May 6, 2016|archive-url=https://web.archive.org/web/20160506171159/https://books.google.com/books?id=4c0Hp3AOi8UC&pg=PA817|url-status=live}}</ref>

Flattened squamous cells are more resistant to both abrasion and infection.<ref name="G and H"/> The permeability of the epithelium allows for an effective response from the [[immune system]] since [[antibodies]] and other immune components can easily reach the surface.<ref name="Anderson">{{Cite journal |vauthors=Anderson DJ, Marathe J, Pudney J |date=June 2014 |title=The Structure of the Human Vaginal Stratum Corneum and its Role in Immune Defense |journal=American Journal of Reproductive Immunology|language=en|volume=71|issue=6|pages=618–623|doi=10.1111/aji.12230|pmid=24661416 |issn=1600-0897|pmc=4024347}}</ref> The vaginal epithelium differs from the similar tissue of the skin. The [[epidermis]] of the skin is relatively resistant to water because it contains high levels of lipids. The vaginal epithelium contains lower levels of lipids. This allows the passage of water and water-soluble substances through the tissue.<ref name="Anderson" />

Keratinization happens when the epithelium is exposed to the dry external atmosphere.<ref name="Dutta"/> In abnormal circumstances, such as in [[Female genital prolapse|pelvic organ prolapse]], the mucosa may be exposed to air, becoming dry and keratinized.<ref name="Dutta2">{{cite book|vauthors=Dutta DC|title=DC Dutta's Textbook of Gynecology|year=2014|publisher=JP Medical Ltd|isbn=978-93-5152-068-9|page=206|url=https://books.google.com/books?id=40yVAwAAQBAJ&pg=PA206|access-date=October 27, 2015|archive-date=May 6, 2016|archive-url=https://web.archive.org/web/20160506172128/https://books.google.com/books?id=40yVAwAAQBAJ&pg=PA206|url-status=live}}</ref>

===Blood and nerve supply===
Blood is supplied to the vagina mainly via the [[vaginal artery]], which emerges from a branch of the [[internal iliac artery]] or the [[uterine artery]].<ref name="Snell" /><ref name="Zimmern">{{cite book|vauthors=Zimmern PE, Haab F, Chapple CR|title=Vaginal Surgery for Incontinence and Prolapse|publisher=[[Springer Science & Business Media]]|isbn=978-1-84628-346-8|year=2007|page=6|url=https://books.google.com/books?id=y5cYRhGJsOsC&pg=PA6|access-date=December 3, 2017|archive-date=July 4, 2019|archive-url=https://web.archive.org/web/20190704043157/https://books.google.com/books?id=y5cYRhGJsOsC&pg=PA6|url-status=live}}</ref> The vaginal arteries [[anastamosis|anastamose]] (are joined) along the side of the vagina with the cervical branch of the uterine artery; this forms the [[Vaginal branches of uterine artery|azygos artery]],<ref name="Zimmern"/> which lies on the midline of the anterior and posterior vagina.<ref name=GRAYS2008 /> Other arteries which supply the vagina include the [[middle rectal artery]] and the [[internal pudendal artery]],<ref name="Dutta"/> all branches of the internal iliac artery.<ref name=GRAYS2008 /> Three groups of lymphatic vessels accompany these arteries; the upper group accompanies the vaginal branches of the uterine artery; a middle group accompanies the vaginal arteries; and the lower group, draining lymph from the area outside the hymen, drain to the [[inguinal lymph node]]s.<ref name=GRAYS2008/><ref>{{Cite book |vauthors=O'Rahilly R |veditors=O'Rahilly R, Müller F, Carpenter S, Swenson R |chapter-url=https://www.dartmouth.edu/~humananatomy/part_6/chapter_32.html |chapter=Blood vessels, nerves and lymphatic drainage of the pelvis |title=Basic Human Anatomy: A Regional Study of Human Structure |publisher=Dartmouth Medical School |language=en |year=2008 |access-date=December 13, 2017 |archive-date=December 2, 2017 |archive-url=https://web.archive.org/web/20171202013014/http://www.dartmouth.edu/~humananatomy/part_6/chapter_32.html |url-status=dead }}</ref> Ninety-five percent of the lymphatic channels of the vagina are within 3&nbsp;mm of the surface of the vagina.<ref name="Sabater">{{Cite journal |vauthors=Sabater S, Andres I, Lopez-Honrubia V, Berenguer R, Sevillano M, Jimenez-Jimenez E, Rovirosa A, Arenas M |date=August 9, 2017|title=Vaginal cuff brachytherapy in endometrial cancer – a technically easy treatment? |journal=Cancer Management and Research|volume=9|pages=351–362|doi=10.2147/CMAR.S119125|issn=1179-1322|pmc=5557121|pmid=28848362 |doi-access=free }}</ref>

Two main veins drain blood from the vagina, one on the left and one on the right. These form a network of smaller veins, the [[vaginal venous plexus]], on the sides of the vagina, connecting with similar venous plexuses of the [[uterine venous plexus|uterus]], [[vesical venous plexus|bladder]], and [[rectal venous plexus|rectum]]. These ultimately drain into the [[internal iliac vein]]s.<ref name=GRAYS2008 />

The nerve supply of the upper vagina is provided by the [[Sympathetic nervous system|sympathetic]] and [[Parasympathetic nervous system|parasympathetic]] areas of the [[Inferior hypogastric plexus|pelvic plexus]]. The lower vagina is supplied by the [[pudendal nerve]].<ref name="Dutta"/><ref name=GRAYS2008/>