Developmental competence of oocytes after ICSI in the rhesus monkey

Oocyte quantity and quality are critical to assisted reproductive technolog y (ART), yet few assessments beyond counting metaphase II (MII) oocytes exi st. In this study, 30 +/- 2 oocytes per cycle were recovered from rhesus mo nkeys subjected to follicular stimulation with human gonadotrophins, of whi ch 15 +/- 1 were Mil, Oocyte quality was investigated by monitoring the dev elopmental potential of oocytes subjected to intracytoplasmic sperm injecti on (ICSI). Despite uniform fertilization rates (71 +/- 4%), progression of embryos to blastocysts varied when expressed as;a monthly average, from 20 to 85%, with lows from February to April and again in October, which could be attributed to developmental failure of a significant number of oocyte co horts (14 of 55), Blastocyst rates, after elimination of failed cohorts, we re uniform over time (59 +/- 4%), Neither culture conditions, the number of follicular stimulations, nor the individual sperm or oocyte donor were ass ociated specifically with developmental failure, suggesting that intrinsic differences between stimulation cycles account for the observed variation i n developmental potential. The in-vivo developmental competence of ICSI-pro duced embryos grown to blastocysts in vitro was also assessed. Two ongoing pregnancies and the birth of a normal female, 'Blastulina', represent landm arks in efforts to expand the use of ART in the rhesus monkey.