The Hutson hypothesis. A clinical study.

The hypothesis that testicular descent may be governed by Müllerian inhibiting substance (MIS) was investigated by observing the position of the testes in 13 children with XY karyotype and persistent Müllerian duct syndrome (PMDS). It was found that there was a direct relationship between failure of testicular descent and the degree of development of the Müllerian system. Where the Müllerian system was complete, the testes were in an ovarian position but where only the vagina was present, the testes were sometimes found in the inguinal region. To discover whether excessive androgen activity in females might produce ovarian descent, the position of the ovaries in 15 children with severe adrenogenital syndrome was observed. Despite complete genital masculinisation in three children and almost complete in six, all but one ovary was in the normal position: that ovary had descended in an inguinal hernia sac. These findings suggest that MIS rather than androgens may be responsible for the first or abdominal phase of testicular descent. Even excessive androgen activity failed to cause ovarian descent.