Editing Testicle (section)

===Internal structure===
[[Image:transversetestis.png|thumb|Transverse section through the left side of the scrotum and the left testis]]

====Duct system====
The testes are covered by a tough fibrous shell called the [[Tunica albuginea of testis|tunica albuginea]].<ref name="Cho">{{Cite book|last1=Cho|first1=S|last2=Bae|first2=J.H.|title=Clinical Regenerative Medicine in Urology|chapter=Penis and Testis|chapter-url=https://books.google.com/books?id=J9s1DwAAQBAJ&pg=PA281|date=2017|publisher=Springer|isbn=978-9-81-102723-9|page=281|access-date=2022-06-01|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629155730/https://books.google.com/books?id=J9s1DwAAQBAJ&pg=PA281|url-status=live}}</ref> Under the tunica albuginea, the testes contain very fine-coiled tubes called [[seminiferous tubule]]s.<ref name="Cho"/> The tubules are lined with a layer of cells ([[germ cell]]s) that develop from [[puberty]] through old age into [[sperm]] [[cell (biology)|cells]] (also known as [[spermatozoa]] or male [[gamete]]s).<ref name="Cho"/> The developing sperm travel through the seminiferous tubules to the [[rete testis]] located in the [[mediastinum testis]], to the [[efferent ducts]], and then to the [[epididymis]] where newly created sperm cells mature ([[spermatogenesis]]).<ref name="Pocock">{{Cite book|last1=Pocock|first1=Gillian|last2=Richards|first2=Christopher D.|last3=Richards|first3=David A.|title=Human Physiology|date=2018|publisher=Oxford University Press|isbn=978-0-19-873722-3|page=766|url=https://books.google.com/books?id=NcQ9DwAAQBAJ&pg=PA766|access-date=2022-06-02|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629155730/https://books.google.com/books?id=NcQ9DwAAQBAJ&pg=PA766|url-status=live}}</ref> The sperm move into the [[vas deferens]], and are eventually expelled through the [[urethra]] and out of the [[External urethral orifice (male)|urethral orifice]] through muscular contractions.<ref name="Pocock"/>

====Primary cell types====
Within the seminiferous tubules, the germ cells develop into [[spermatogonia]], [[spermatocyte]]s, [[spermatid]]s and spermatozoa through the process of spermatogenesis. The gametes contain DNA for fertilization of an [[ovum]].<ref>[https://books.google.com/books?id=FoSiGTXn6BUC&q=testes+OR+testis+OR+testicle+OR+testicles Histology, A Text and Atlas] {{Webarchive|url=https://web.archive.org/web/20230629155731/https://books.google.com/books?id=FoSiGTXn6BUC&q=testes+OR+testis+OR+testicle+OR+testicles |date=2023-06-29 }} by Michael H. Ross and Wojciech Pawlina, Lippincott Williams & Wilkins, 5th ed, 2006{{page needed|date=April 2022}}</ref> Sertoli cells{{Snd}}the true epithelium of the seminiferous epithelium, critical for the support of germ cell development into spermatozoa. Sertoli cells secrete [[inhibin]].<ref name="Huhtaniemi">{{Cite book|last=Huhtaniemi|first=Ilpo|title=Encyclopedia of Endocrine Diseases|date=2018|publisher=Academic Press|isbn=978-0-12-812200-6|page=667|url=https://books.google.com/books?id=nVh7DwAAQBAJ&pg=RA1-PA667|access-date=2022-06-02|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629155732/https://books.google.com/books?id=nVh7DwAAQBAJ&pg=RA1-PA667|url-status=live}}</ref> [[Peritubular myoid cells]] surround the seminiferous tubules.<ref name="Schlegel">{{Cite book|last1=Schlegel|first1=P.N.|last2=Katzovitz|first2=M.A.|title=Urologic Principles and Practice|chapter=Male Reproductive Physiology|chapter-url=https://books.google.com/books?id=bNHHDwAAQBAJ&pg=PA50|date=2020|publisher=Springer Nature|isbn=978-3-03-028599-9|page=50|access-date=2022-06-02|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629155757/https://books.google.com/books?id=bNHHDwAAQBAJ&pg=PA50|url-status=live}}</ref>

Between tubules (interstitial cells) exist [[Leydig cells]]<ref name="Bitzer">{{Cite book|last1=Bitzer|first1=Johannes|last2=Mahmood|first2=Tahir A.|title=Handbook of Contraception and Sexual Reproductive Healthcare|date=2022|publisher=Cambridge University Press|isbn=978-1-10-895863-9|page=16|url=https://books.google.com/books?id=WWtYEAAAQBAJ&pg=PA16|access-date=2022-07-05|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629155732/https://books.google.com/books?id=WWtYEAAAQBAJ&pg=PA16|url-status=live}}</ref>{{Snd}}cells localized between seminiferous tubules that produce and secrete [[testosterone]] and other [[androgen]]s important for [[puberty]] (including [[secondary sexual characteristics]] like facial hair), [[Human sexual activity|sexual behavior]], and [[libido]]. Sertoli cells support spermatogenesis.<ref name="Miell">{{Cite book|last1=Miell|first1=John|last2=Davies|first2=Zoe|title=Clinical Biochemistry: Metabolic and Clinical Aspects|chapter=Reproductive function in the male|chapter-url=https://books.google.com/books?id=2FkXAwAAQBAJ&pg=PA451|date=2014|publisher=Elsevier Health Sciences|isbn=978-0-70-205478-5|page=451|access-date=2022-07-05|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160234/https://books.google.com/books?id=2FkXAwAAQBAJ&pg=PA451|url-status=live}}</ref> Testosterone controls testicular volume.

Immature Leydig cells and interstitial [[macrophage]]s and [[epithelial cells]] are also present.

====Blood supply and lymphatic drainage====
The testis has three sources of arterial blood supply: the [[testicular artery]], the [[cremasteric artery]], and the [[artery to the ductus deferens]].<ref name="Goldenberg">{{Cite book|last1=Goldenberg|first1=Etai|last2=Benjamin|first2=Tavya G.R|last3=Gilbert|first3=Bruce R.|title=Practical Urological Ultrasound|chapter=Scrotal Ultrasound|date=2020|publisher=Springer Nature|isbn=978-3-03-052309-1|page=80|chapter-url=https://books.google.com/books?id=QU8AEAAAQBAJ&pg=PA80|access-date=2022-07-06|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160234/https://books.google.com/books?id=QU8AEAAAQBAJ&pg=PA80|url-status=live}}</ref> Blood supply and [[lymphatic drainage]] of the testes and scrotum are distinct:
* The paired testicular arteries arise directly from the [[abdominal aorta]] and descend through the [[inguinal canal]], while the scrotum and the rest of the external genitalia is supplied by the [[internal pudendal artery]] (a branch of the [[internal iliac artery]]).<ref name="Steger 2"/><ref name="Tortora">{{Cite book|last1=Tortora|first1=Gerard J.|last2=Nielsen|first2=Mark|title=Principles of Human Anatomy|date=2017|publisher=John Wiley & Sons|isbn=978-1-11-944446-6|page=486|url=https://books.google.com/books?id=e0rcDwAAQBAJ&pg=PA486|access-date=2022-07-06|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160234/https://books.google.com/books?id=e0rcDwAAQBAJ&pg=PA486|url-status=live}}</ref>
* The testis has collateral blood supply from the cremasteric artery (a branch of the [[inferior epigastric artery]], which is a branch of the [[external iliac artery]]), and the artery to the ductus deferens (a branch of the [[inferior vesical artery]], which is a branch of the internal iliac artery).<ref name="Pua">{{Cite book|last1=Pua|first1=Bradley B.|last2=Covey|first2=Anne M.|last3=Madoff|first3=David C.|title=Interventional Radiology: Fundamentals of Clinical Practice|date=2018|publisher=Oxford University Press|isbn=978-0-19-027625-6|page=533|url=https://books.google.com/books?id=edB2DwAAQBAJ&pg=PA533|access-date=2022-07-06|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160235/https://books.google.com/books?id=edB2DwAAQBAJ&pg=PA533|url-status=live}}</ref><ref name="Berney">{{Cite book|last1=Berney|first1=Daniel M|last2=Ulbright|first2=Thomas M.|title=Genitourinary Pathology: Practical Advances|chapter=Anatomy of the Testis and Staging of its Cancers: Implications for Diagnosis|date=2015|publisher=Springer|isbn=978-1-49-392044-0|page=436|chapter-url=https://books.google.com/books?id=97RnBwAAQBAJ&pg=PA436|access-date=2022-07-06|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160304/https://books.google.com/books?id=97RnBwAAQBAJ&pg=PA436|url-status=live}}</ref> Therefore, if the testicular artery is ligated, e.g., during a Fowler-Stevens [[orchiopexy]] for a high undescended testis, the testis will usually survive on these other blood supplies.<ref name="Aboumarzouk">{{Cite book|last=Aboumarzouk|first=Omar M.|title=Blandy's Urology|date=2019|publisher=John Wiley & Sons|isbn=978-1-11-886336-7|page=747|url=https://books.google.com/books?id=WsaKDwAAQBAJ&pg=PA747|access-date=2022-07-06|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160244/https://books.google.com/books?id=WsaKDwAAQBAJ&pg=PA747|url-status=live}}</ref>
* Lymphatic drainage of the testes follows the testicular arteries back to the [[paraaortic lymph nodes]], while lymph from the scrotum drains to the [[inguinal lymph nodes]].<ref name="Steger 2"/><ref name="Berney"/>

====Layers====
[[File:Layers of the Scrotum.ogg|thumb|3D anatomy of the layers surrounding the testis]]

Many anatomical features of the adult testis reflect its developmental origin in the [[abdomen]]. The layers of tissue enclosing each testicle are derived from the layers of the anterior [[abdominal wall]].<ref name="Steger"/> The [[cremasteric muscle]] arises from the [[internal oblique muscle]].<ref name="Steger"/><ref name="Tubbs">{{Cite book|last1=Tubbs|first1=R. Shane|last2=Shoja|first2=Mohammadali M.|last3=Loukas|first3=Marios|title=Bergman's Comprehensive Encyclopedia of Human Anatomic Variation|date=2016|publisher=John Wiley & Sons|isbn=978-1-11-843068-2|page=1393|url=https://books.google.com/books?id=U_0dDAAAQBAJ&pg=PT1393|access-date=2022-06-03|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160506/https://books.google.com/books?id=U_0dDAAAQBAJ&pg=PT1393|url-status=live}}</ref>

====The blood–testis barrier====
{{main|Blood–testis barrier}}
Large molecules cannot pass from the blood into the lumen of a seminiferous tubule due to the presence of [[tight junction]]s between adjacent Sertoli cells.<ref name="Steger 2">{{Cite book|last1=Steger|first1=Klaus|last2=Weidner|first2=Wolfgang|title=Practical Urology: Essential Principles and Practice|chapter=Anatomy of the Male Reproductive System|chapter-url=https://books.google.com/books?id=A9m8TkdCUqEC&pg=PA63|date=2011|publisher=Springer Science & Business Media|isbn=978-1-84-882034-0|page=63|access-date=2022-06-05|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160505/https://books.google.com/books?id=A9m8TkdCUqEC&pg=PA63|url-status=live}}</ref> The spermatogonia occupy the basal compartment (deep to the level of the tight junctions) and the more mature forms, such as primary and secondary spermatocytes and spermatids, occupy the adluminal compartment.<ref name="Steger 2"/>

The function of the blood–testis barrier may be to prevent an [[auto-immune]] reaction.<ref name="Steger 2"/> Mature sperm (and their [[antigen]]s) emerge significantly after immune tolerance is set in infancy.<ref name="Steger 2"/> Since sperm are antigenically different from self-tissue, a male animal can react immunologically to his own sperm. The male can make antibodies against them.<ref name="Steger 2"/>

Injection of sperm antigens causes inflammation of the testis (auto-immune orchitis) and reduced fertility.<ref name="Steger 2"/> The blood–testis barrier may reduce the likelihood that sperm proteins will induce an immune response.<ref name="Wiser">{{Cite book|last1=Wiser|first1=Herbert J.|last2=Sandlow|first2=Jay|last3=Kohler|first3=Tobias S.|title=Male Infertility: Contemporary Clinical Approaches, Andrology, ART & Antioxidants|chapter=Causes of Male Infertility|chapter-url=https://books.google.com/books?id=W8pplg2vbEUC&pg=PA8|date=2012|publisher=Springer Science & Business Media|isbn=978-1-46-143335-4|page=8|access-date=2022-07-10|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160509/https://books.google.com/books?id=W8pplg2vbEUC&pg=PA8|url-status=live}}</ref>