Somatic cell fate maintenance in mouse fetal testes via autocrine/paracrine action of AMH and activin B

Fate determination and maintenance of fetal testes in most mammals occur cell autonomously as a result of the action of key transcription factors in Sertoli cells. However, the cases of freemartin, where an XX twin develops testis structures under the influence of an XY twin, imply that hormonal factor(s) from the XY embryo contribute to sex reversal of the XX twin. Here we show that in mouse XY embryos, Sertoli cell-derived anti-Mullerian hormone (AMH) and activin B together maintain Sertoli cell identity. Sertoli cells in the gonadal poles of XY embryos lacking both AMH and activin B transdifferentiate into their female counterpart granulosa cells, leading to ovotestis formation. The ovotestes remain to adulthood and produce both sperm and oocytes, although there are few of the former and the latter fail to mature. Finally, the ability of XY mice to masculinize ovaries is lost in the absence of these two factors. These results provide insight into fate maintenance of fetal testes through the action of putative freemartin factors. Fate determination and maintenance of foetal testes in most animals occurs cell autonomously. Here the authors show in mouse XY embryos that Sertoli cell derived AMH and activin B together maintain Sertoli cell identity, and lack of both AMH and activin B leads to transdifferentiation into female granulosa cells.

Automated summary

In most animals, the fate determination and maintenance of fetal testes occur cell autonomously. In XY mouse embryos, Sertoli cell-derived anti-Mullerian hormone (AMH) and activin B together maintain the identity of Sertoli cells, and the absence of these factors leads to transdifferentiation into female granulosa cells, resulting in ovotestis formation.