ANTI-MULLERIAN HORMONE IN EARLY HUMAN DEVELOPMENT

Abstract

Anti-Mullerian hormone (AMH), also called Mullerian-inhibiting substance or factor, is a dimeric glycoprotein, produced by immature Sertoli cells, and responsible for Mullerian regress ion in male fetuses. To study the ontogeny of AMH production in the male against human recombinant AMH, the AMH concentration in 21 samples of amniotic fluid and 44 samples of fetal serum, initially collected for cytogenetical analysis in fetuses with sonographic abnormalities. No AMH was detectable in amnitotic fluid, whatever the fetal sex. Mean ± SEM AMH concentration was 40.5 ± 3.9 ng/ml in the serum of male fetuses from 19 to 30 weeks, and 28.4 ± 6.1 ng/ml in older ones. The AMH concentration in the serum of an male XX fetus, aged 24 weeks, 48.3 ng/ml, was the only biological indicator of fetal sex. No AMH was detectable in female serum at any time, allowing easy discrimination between male and female samples, even during the perinatal period, when mean scrum AMH concentration is decreased, compared to that of infants aged 2 months to 2 years (43.1 ± 3.7? P>0.05). AMH production in early fetal life was studied by in-situ hybridization, using AMH-specific sense and antisense riboprobes. AMH transcripts were detected in the Sertoli cells of fetuses aged 8 weeks or older, but not in ovarian tissue. Negative results were also found in the sexually undifferentiated gonadal tissue of one 7-week-old fetus, with detectable DMA SRY-specific sequences, confirming that AMH expression in the testis begins only after seminiferous tubule differentiation.