[Testicular graft on the chick embryo].

A testis from an 18-day-old chick embryo was transplanted into the extra-coelomic cavity of 3-4-day-old hosts. The embryos surviving at 17 days were sacrificed and their genital system was examined. Testis grafting produced inhibition of testicular development. Development of the female gonads was also inhibited. A more or less complete modification of sex was associated with this inhibition. The left ovary lost its cortex, but its medulla remained mostly ovarian in structure. The right gonad frequently acquired a typical testicular structure. These results confirm the possibility of obtaining sex reversal in the female chick embryo by testis grafting.