Sexing of Bovine Embryos with Male-Specific Repetitive DNA by Polymerase Chain Reaction: Sexing of Bovine Embryos and Production of Calves with Predicted Sex.

Abstract

We have previously cloned and characterized both bovine male-specific and genderneutral DNA's. Primers for the polymerase chain reaction (PCR) were synthesized on the basis of these DNA's to give differential PCR products between males and females. Serial dilution of bovine somatic cells of both sexes revealed that 10 cells were sufficient to discriminate males from females under our conditions. The usefulness of our primers to sex bovine embryos was confirmed by using purified control DNA's, cytogenetic analysis of demi-embryos, coincidence of a pair of asymmetrical biopsy samples and embryo transfer. All the embryos used here were produced by in vitro fertilization and culture methods. A successful determination of sex was made for 83 out of 84 embryos examined (98.8%). The sex ratio (54.2% male) did not differ significantly from the expected 1:1 ratio. The viability of biopsied embryos (86.3%) after 24 h culture in vitro was not significantly different from that of intact embryos (92.3%). Also, the mean numbers of cells of the biopsied (153.1, n=42) and intact (170.7, n=39) embryos were not significantly different. Out of seven recipients received the embryos with predicted sex, three went to term, producing one male and 2 female calves in accordance with the sex prediction before transfer. In conclusion, our method appears to be an efficient and reliable one to determine the sex of bovine preimplantation embryos.