Increasing post-transplantation survival rates of sexed frozen/thawed embryos by improving embryo biopsy techniques.

Abstract

The purpose of this paper was to find the most suitable embryo biopsy technique that would yield the highest pregnancy rates after the transfer of sexed embryos to recipients. Three methods of embryo biopsy (needle, blade or aspiration) were applied on 60 bovine embryos divided into 3 batches (n=20) in order to harvest the blastomeres needed for polymerase chain reaction (PCR) embryo sexing. After performing the biopsies, the embryos were frozen/thawed and then transferred into synchronized recipients. DNA was extracted from the blastomeres and was subsequently amplified using bovine Y-chromosome specific primers, in order to determine the sex of the embryo. The pregnancy diagnosis and the assessment of pregnancy rate were performed 30 days later using an ultrasound scanner. The results showed a significant difference in pregnancy rates according to the biopsy method used: 55% for the needle biopsy, 45% for the aspiration method and 30% for the microblade technique. The accuracy of the PCR sexing method was comparable in all batches, and therefore was not influenced by the biopsy method. The needle method of embryo biopsy proved to be the most suitable as it yielded the highest pregnancy rates and can be successfully applied when harvesting blastomeres for embryo sexing. Key