In Weekly Themes, mav brought up the word "adnate".
But what would be the word to describe the behaviour of the testicle, which orig;inates close to the kidneys, but is prgressively separated from them, until it lies outside the "abominable" cavity? I don't remember the word used in embryology, but it might have been "migration". The change seems to have been favored by the fact that sperm do not develop as readily at slightly greater temperature of the abdomen.