Experimental Reversal of Germ Cells in Ovaries of Fetal Mice.

When heterosexual pairs of gonads of fetal mice were homotransplanted in close contact with each other below the kidney capsule of castrated adult hosts, the testis developed normally for this environment, but the ovary became an ovotestis. The medulla of the ovotestis contained dilated seminiferous tubules in which spermatogenesis progressed to the point at which secondary spermatocytes were produced. Under these conditions, germ cells, genetically determined as ova, underwent differentiation toward spermatozoa. This is the second clear case of germ cell reversal by experimental means in a mammalian species.