Expression of the mouse anti-müllerian hormone gene suggests a role in both male and female sexual differentiation.

We describe here the isolation of cDNA and genomic clones corresponding to the mouse gene encoding anti-Müllerian hormone, and the use of these clones as molecular probes to study AMH gene expression. We constructed a 14.5 days post coitum (dpc) mouse fetal testes library and isolated a cDNA clone using bovine, human and rat partial cDNAs as probes. This clone contained a 1 kb insert, which was confirmed by sequencing to be the mouse homologue of AMH. Probes derived from the mouse cDNA clone were used to screen genomic libraries and a 12 kb DNA fragment containing the complete coding region of mouse AMH was isolated. In situ hybridisation was used to determine the precise timing and localisation of AMH expression in male and female embryos and postnatal testes and ovaries. AMH transcripts were first detected in fetal testes at 12.5 dpc when differences between testes and ovaries first become visible. The signal was specific for the Sertoli cells of the testes. Other fetal tissues or female embryos were negative for AMH transcripts. During male development, AMH expression is shut off postnatally. In the female, the expression of AMH was first detected at day 6 after birth and is restricted to granulosa cells. We have correlated the pattern of AMH expression in both sexes with cellular events occurring in gonadal development and discuss some implications that this may have for its function and regulation.