THE HUMAN SPERM-SURVIVAL, 2-CELL ZONA-FREE, AND ONE-CELL ZONA-INTACT ASSAYS FOR IVF QUALITY-CONTROL

Objective-To compare the 4-day human sperm-survival (SS) assay, the mu rine 2-cell zona-free assay, and the murine 1-cell zona-intact assay f or capacity to detect toxins and culture conditions known to adversely affect the survival/developmental potential of human embryos during I VF. Methods-Three studies were carried out. In Study I, human sperm su rvival (SS) and two-cell zona-free (2CZF) assays were evaluated for th eir sensitivity and precision in testing a wide array of items for IVF quality control. For general laboratory items containing a rubber com ponent, the SS and 2CZF assays were able to detect 72% and 44%, respec tively, of the items with known toxicity. For testing of oil overlays, media, and water, the SS and 2CZF assays detected only 6% and 16%, re spectively, of toxins/culture solutions considered inadequate for huma n IVF. In Studies II and III, we investigated whether oil overlays cou ld decrease the sensitivity of the murine bioassays by absorbing toxin s from the test media. For the 2CZF and 1-cell zona-intact (1CZI) assa ys, the oil overlays resulted in a decreased number of tests in which a toxin was identified (10% vs. 35% and 35% vs. 42%, respectively). In the absence of oil overlays, significantly lower development of test embryos exposed to toxins was noted in 8/20 (40%) and 3/18 (17%) tests for the 2CZF and 1CZI assays, respectively. Under the best assay cond itions used in this study (no oil overlays), only 6%, 35%, and 42% of toxins were detected with the SS, 2CZF, and 1CZI assays, respectively. Conclusions-The results of these studies indicate that oil overlays d ecrease the sensitivity of IVF quality control assays. The SS assay ap pears to be adequate for quality control testing of items with a rubbe r component. Using the methods and end points employed in these studie s, all of the assays investigated appeared to be too insensitive for I VF quality control testing of oil, media, and water.