Fig. 5. Testis cord morphogenesis in Sf1 and Dax1 mutant male gonads. Testis differentiation is characterized by morphogenesis of primitive testis cords in tissue stained by Hematoxylin and Eosin. Cross-sectional histology of wild-type gonad tissue shows round cord structures containing Sertoli and germ cells enclosed by flattened peritublar myoid cells (A). Sf1 heterozygous gonads retain cord morphology (B). Dax1 null (C) and Sf1/Dax1 double mutant (D) gonad tissue both show a more disorganized patterning, reflecting Dax1 deficiency in both cases.