Functional capacity of sex-reversed (XX, Sxr/+) mouse germ cells as shown by progeny derived from XX, Sxr/+ oocytes of a female chimera.

Mice of the genotype X/X, Sxr/+ (Sex-reversed) are sterile phenotypic males. Testis size is reduced and there is a failure of spermatogenesis during meiosis I. A female chimeric mouse has been produced whose germ line is entirely composed of X/X, Sxr/+ germ cells. The progeny of this chimera included several XX, Sxr/+ males. The finding that X/X, Sxr/+ germ cells can produce fully functional oocytes has implications for the function of the Sex-reversed gene, the control of germ cell differentiation, and the role of germ cells in primary sex determination.