In vitro development of human oocytes after parthenogenetic activation or intracytoplasmic sperm injection.

OBJECTIVE To compare directly in vitro developmental competence between parthenogenetically activated and intracytoplasmic sperm injection (ICSI)-fertilized oocytes. DESIGN For each patient, three metaphase II oocytes were randomized to the ICSI procedure, while n-3 were allocated to parthenogenetic activation. SETTING University hospital infertility unit. PATIENTS Thirty-eight patients, aged 35.2 +/- 3.3 years (mean +/- SD) selected for ICSI. INTERVENTIONS After 1 hour from denudation, oocytes were either fertilized by ICSI (n = 114) or chemically activated (n = 104). Fertilized and activated oocytes were cultured for up to 3 and 5 days, respectively. MAIN OUTCOME MEASURES Development rate, cell number, and morphological grade during culture. RESULTS The two groups showed no significant differences between rates of fertilization and parthenogenetic activation, development, and blastomere number on days 2 and 3 of culture. However, parthenotes showed a lower morphological grade, and a significantly lower proportion went on cleaving to day 3, when only activated rather than total numbers of oocytes were considered. On day 5 after activation, nine oocytes (8.6%) reached the blastocyst stage, representing 12.9% of parthenotes. CONCLUSIONS Since most parameters examined in this study were similar between activated and fertilized oocytes, parthenogenetic activation may be a useful tool for the preclinical evaluation of experimental procedures.