SUBZONAL INSEMINATION OF IMMATURE OOCYTES GENERATED DURING INTRACYTOPLASMIC INJECTION CYCLES

Our purpose was to determine whether immature [metaphase I (MI); germi nal vesicle (GV) stage] oocytes recovered during intracytoplasmic inje ction (ICSI) cycles can be fertilized by subzonal insemination (SUZI). We recovered 319 oocytes from 36 patients undergoing ICSI, of which 3 2 (10%) were MI-stage oocytes and 36 (11.3%) were GV-stage oocytes. 32 MI-stage and 32 of 36 GV-stage oocytes were subjected to SUZI on day of oocyte retrieval (OR). 31.1% of MI-stage oocytes fertilized after S UZI and developed to two-cell to four-cell stage embryos within 48 h a fter OR. Of the 32 GV-stage oocytes only 6.3% fertilized 24 and 48 h a fter OR and developed to two-cell embryos the following day. We conclu de that MI-stage oocytes can be fertilized by SUZI which subsequently proceeded to the two-cell to four-cell stages by 48 h after OR. SUZI c an, therefore, be routinely applied to rescue MI-stage embryos generat ed during ICSI cycles. Further investigations are required to salvage GV-stage oocytes. (C) 1998 Lippincott-Raven Publishers.