Editing Frog (section)

===Reproductive system===
{{See also|Sexual selection in amphibians}}
In the male frog, the two [[Testis|testes]] are attached to the kidneys and [[semen]] passes into the kidneys through fine tubes called [[efferent ducts]]. It then travels on through the ureters, which are consequently known as urinogenital ducts. There is no penis, and sperm is ejected from the cloaca directly onto the eggs as the female lays them. The ovaries of the female frog are beside the kidneys and the eggs pass down a pair of oviducts and through the cloaca to the exterior.<ref name=TutorVista/>

When frogs mate, the male climbs on the back of the female and wraps his fore limbs round her body, either behind the front legs or just in front of the hind legs. This position is called [[amplexus]] and may be held for several days.<ref>{{cite book | last1=Duellman |first1=William E. |last2=Trueb |first2=Linda |author-link2=Linda Trueb | date = 1986 | title = Biology of Amphibians | location = New York | publisher = McGraw-Hill Publishing Company }}</ref> The male frog has certain hormone-dependent [[secondary sexual characteristic]]s. These include  the development of special pads on his thumbs in the breeding season, to give him a firm hold.<ref>{{cite web |url=http://www2.southeastern.edu/Academics/Faculty/dsever/SeverandStaub.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www2.southeastern.edu/Academics/Faculty/dsever/SeverandStaub.pdf |archive-date=October 9, 2022 |url-status=live |title=Hormones, sex accessory structures, and secondary sexual characteristics in amphibians |author1=Sever, David M. |author2=Staub, Nancy L. |pages=83–98 |work=Hormones and Reproduction of Vertebrates&nbsp;– Vol 2: Amphibians |access-date=August 4, 2012}}</ref> The grip of the male frog during amplexus stimulates the female to release eggs, usually wrapped in jelly, as spawn. In many species the male is smaller and slimmer than the female. Males have vocal cords and make a range of croaks, particularly in the breeding season, and in some species they also have [[vocal sac]]s to amplify the sound.<ref name=TutorVista/>