Abstract
Hypophyses of [male] rats, 1-21 days old, were implanted into hypophysectomized adult [male] rats daily for 3 days. Hypophysectomized and 21-day normals were controls. Hypophyses from rats 1-13 days old did not affect external genitals or seminal vesicle weight of hypophysectomized recipients, but did affect 21-day normals. Hypophyses from rats 13-21 days old did affect both hypophysectomized and normal recipients, the most potent being from 21-day old rats.