MALE SEX CHORD VESTIGES. “Primary and secondary sex cords in indifferent gonads. Primary sex cords of the gonad’s medullary region become Sertoli cells of the seminiferous tubules that comprise the majority of the testes; later rete cords (AKA cords of urogenital union) connect these to the efferent duct (essentially, the vas deferens).”
https://evolution-outreach.springeropen.com/articles/10.1186/s12052-014-0012-5