201 FACTORS AFFECTING THE SURVIVAL OF BIOPSIED RHESUS MACAQUE EMBRYOS

Abstract

The rhesus macaque (Macaca mulatta) is widely used for the study of human disease. Increasingly assisted reproductive techniques are applied to the propagation of this species to identify specific genotypes, to generate animals with genetic modifications, or to preserve valuable genetic resources. A significant advantage in this endeavor would be the ability to identify embryos with desired genetic characteristics by pre-implantation genetic diagnosis (PGD) prior to their transfer into a surrogate. The objectives of this study, therefore, were to assess the feasibility of performing blastomere biopsies on rhesus embryos and to determine the effects of (a) oxygen tension during culture, (b) transient cryopreservation, and (c) the number of blastomeres removed (one or two) on subsequent development. A total of 17 oocyte aspirations were performed, which resulted in 206 8- to 10-cell embryos that were selected for biopsy. Embryos were cultured in HECM-9 medium and cryopreserved with propylene glycol. The chi-square test was used for data analysis. For the first experiment, 160 embryos were used to assess the effect of oxygen tension and transient cryopreservation. Oxygen tension during culture had no effect on the number of embryos proceeding to the blastocyst stage (26.0 vs. 25.0%) following blastomere removal. Similarly, transient freezing and storage in liquid nitrogen did not affect subsequent development to the blastocyst stage (26.6 vs. 24.7%). For the second experiment, 46 embryos were biopsied and assigned to removal of either one or two blastomeres. Subsequent development was not affected by the number of blastomeres removed, and a similar percentage of embryos reached the blastocyst stage (38.1 vs. 20%). These results demonstrate that rhesus embryos are tolerant of biopsies and proceed to advanced stages of development at the same rate as control embryos.

Funding was provided by the Tulane National Primate Research Center base grant NIH 5P51 RR00164-44.