Editing Testicle (section)

===Temperature regulation and responses===
[[Carl Richard Moore]] in 1926 <ref name="Moore 1926 pp. 4–50">{{cite journal |last=Moore |first=Carl R. |date=1926 |title=The Biology of the Mammalian Testis and Scrotum |journal=The Quarterly Review of Biology |volume=1 |issue=1 |pages=4–50 |doi=10.1086/394235 |issn=0033-5770}}</ref> proposed that testicles were external due to [[spermatogenesis]] being enhanced at temperatures slightly less than core body temperature outside the body. The spermatogenesis is less efficient at lower and higher temperatures than 33&nbsp;°C. Because the testes are located outside the body, the smooth tissue of the scrotum can move them closer or further away from the body.<ref name="Cho"/> The temperature of the testes is maintained at 34.4&nbsp;°C, a little below body temperature, as temperatures above 36.7&nbsp;°C impede spermatogenesis.<ref name="Steger"/><ref name="Cho"/> There are a number of mechanisms to maintain the testes at the optimum temperature.<ref name="Coad">{{Cite book|last1=Coad|first1=Jane|last2=Pedley|first2=Kevin|last3=Dunstall|first3=Melvyn|title=Anatomy and Physiology for Midwives E-Book|date=2019|publisher=Elsevier Health Sciences|isbn=978-0-70-206665-8|pages=53–54|url=https://books.google.com/books?id=YnetDwAAQBAJ&pg=PA53|access-date=2022-06-17|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160508/https://books.google.com/books?id=YnetDwAAQBAJ&pg=PA53|url-status=live}}</ref>

The cremasteric muscle covers the testicles and the [[spermatic cord]].<ref name="de Jong">{{Cite book|last=de Jong|first=M. Robert|title=Sonography Scanning E-Book: Principles and Protocols|date=2020|publisher=Elsevier Health Sciences|isbn=978-0-32-376425-4|page=343|url=https://books.google.com/books?id=BvcCEAAAQBAJ&pg=PA343|access-date=2022-06-05|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160507/https://books.google.com/books?id=BvcCEAAAQBAJ&pg=PA343|url-status=live}}</ref> When this muscle contracts, the cord shortens and the testicles move closer up toward the body, which provides slightly more warmth to maintain optimal testicular temperature.<ref name="de Jong"/> When cooling is required, the cremasteric muscle relaxes and the testicles lower away from the warm body and are able to cool.<ref name="de Jong"/> Contraction also occurs in response to [[Stress (biology)|physical stress]], such as blunt trauma; the testicles withdraw and the scrotum shrinks very close to the body in an effort to protect them.<ref name="Song">{{Cite book|last1=Song|first1=David H|last2=Neligan|first2=Peter C|title=Plastic Surgery E-Book: Volume 4: Trunk and Lower Extremity|date=2017|publisher=Elsevier Health Sciences|isbn=978-0-32-335707-4|page=293|url=https://books.google.com/books?id=cR0xDwAAQBAJ&pg=PA293|access-date=2022-06-10|archive-date=2023-06-29|archive-url=https://web.archive.org/web/20230629160507/https://books.google.com/books?id=cR0xDwAAQBAJ&pg=PA293|url-status=live}}</ref>

The [[cremasteric reflex]] will reflexively raise the testicles. The testicles can also be lifted voluntarily using the [[pubococcygeus]] muscle, which partially activates related muscles.