Editing Hormone (section)

===Arnold Adolph Berthold (1849)===

[[Arnold Adolph Berthold]] was a German [[physiology|physiologist]] and [[zoology|zoologist]], who, in 1849, had a question about the function of the [[testicle|testes]]. He noticed in castrated roosters that they did not have the same sexual behaviors as [[rooster]]s with their testes intact. He decided to run an experiment on male roosters to examine this phenomenon. He kept a group of roosters with their testes intact, and saw that they had normal sized wattles and combs (secondary [[sex organ|sexual organs]]), a normal crow, and normal sexual and aggressive behaviors. He also had a group with their testes surgically removed, and noticed that their secondary sexual organs were decreased in size, had a weak crow, did not have sexual attraction towards females, and were not aggressive. He realized that this organ was essential for these behaviors, but he did not know how. To test this further, he removed one testis and placed it in the abdominal cavity. The roosters acted and had normal physical [[anatomy]]. He was able to see that location of the testes does not matter. He then wanted to see if it was a [[genetics|genetic]] factor that was involved in the testes that provided these functions. He transplanted a testis from another rooster to a rooster with one testis removed, and saw that they had normal behavior and physical anatomy as well. Berthold determined that the location or genetic factors of the testes do not matter in relation to sexual organs and behaviors, but that some [[chemical]] in the testes being secreted is causing this phenomenon. It was later identified that this factor was the hormone [[testosterone]].<ref name="Belfiore_2018">{{cite book |title=Principles of Endocrinology and Hormone Action | vauthors = Belfiore A, LeRoith PE |isbn=978-3-319-44675-2|location=Cham | publisher = Springer |oclc=1021173479|date=2018}}</ref><ref>{{cite book |title=Endocrine Physiology| veditors = Molina PE |date= 2018|publisher= McGraw-Hill Education |isbn=978-1-260-01935-3 |oclc=1034587285}}</ref>