Anti-Müllerian hormone: a local or long-distance morphogenetic factor?

In an attempt to determine whether anti-Müllerian hormone could exert long-distance effects, we studied the anti-Müllerian activity of gonads from bovine Freemartin fetuses. Anti-Müllerian activity was detected in 3 out of the 7 animals studied: one was 62 days old, and its gonad contained undifferentiated tissue only; the 2 others were 110 and 130 days old respectively, and their gonads contained seminiferous tubules. The gonads devoid of anti-Müllerian activity contained only rete tubules or fibrous tissue. Anti-Müllerian activity was absent in fetal male and Freemartin serum, except in 2 cases, in which low activity was present after 37-fold purification by lectin affinity chromatography. The presence of anti-Müllerian activity in Freemartin gonads with seminiferous tubules is an indication that gonadal virilization in these fetuses is functional as well as morphological. Further experiments are needed to determine whether regression of the Müllerian ducts in the Freemartin is due to anti-Müllerian hormone produced by the Freemartin gonads in situ.