Testis Cord

The testis cord is the earliest morphological sign of testis differentiation, and is discernible at approximately 36 hours following SRY expression, between E12.0-12.5. The testis cord comprises aggregates of germ cells surrounded by a layer of Sertoli cells, which are, in turn, encased by peritubular myoid cells. Eventually, the testis cord matures into the seminiferous tubules of the adult testis.