Cloning and expression of the chick anti-Müllerian hormone gene

Müllerian duct regression in male embryos is due to early production by fetal Sertoli cells of anti-Müllerian hormone, a homodimeric protein of the transforming growth factor- beta superfamily. In mammals, both female Müllerian ducts develop into the uterus and Fallopian tubes, whereas in birds, the right oviduct does not develop. To gain insight into sex differentiation in birds, we have cloned the cDNA for chick anti-Müllerian hormone using antibodies raised against the partially purified protein. Expression cloning was required because of the lack of cross-hybridization between mammalian and chick anti-Müllerian hormone DNA. The chick DNA and protein are significantly longer, due to insertions that abolish nucleotide homology, except in the cDNA coding for the C-terminal, bioactive part of the protein. Nevertheless, the general structure of the gene, sequenced from the transcription initiation to the polyadenylation site, and the main features of the protein are conserved between the chick and mammals. The chick anti-Müllerian hormone gene is expressed at high levels in Sertoli cells of the embryonic testes and in lower amounts in both ovaries, higher levels being reached on the left side after 10 days of incubation.