A technique for sexing mouse embryos by a visual colorimetric assay of the X-linked enzyme, glucose 6-phosphate dehydrogenase.

Described is a simple visual, colorimetric assay for the X-linked enzyme, glucose 6-phosphate dehydrogenase (G6PD), in mouse embryos. Included is a demonstration of the effectiveness of the assay in predicting the sex of embryos prior to transfer. Scoring of embryos according to G6PD content resulted in an apparent bimodal distribution with 50% scoring as females, i.e., double dosage of G6PD, and 50% scoring as males, i.e., single dosage of G6PD. Transfer of "sexed" embryos to surrogate mothers resulted in an overall birth rate of 35% (181 516 ) compared to 46% (39 84 ) for controls. Embryos predicted as females resulted in a birth rate of 35% (86 247 ), and 72% (62 86 ) of pups born were female. Embryos predicted as males resulted in a birth rate of 35% (95 269 ), and 57% (54 95 ) of pups born were male. Overall, the accuracy of the assay was 64% (116 181 ) in predicting sex, i.e., about two-thirds of the embryos were correctly sexed prior to transfer.