Archambeault, D., Tomaszewski, J., Childs, A. J., Anderson, R. A., & Yao, H. H. Testicular somatic cells, not gonocytes, and the major source of functional activin A during testis morphogenesis. Endocrinology, 152(11), 4358-67. https://doi.org/10.1210/en.2011-1288