Comparison of sperm binding potential of uninseminated, inseminated‐unfertilized, and fertilized‐noncleaved human oocytes under hemizona assay conditions

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Abstract
In this study, human oocytes obtained after ovarian hyperstimulation for in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) were utilized to evaluate sperm/zona pellucida binding potential. Three groups of oocytes were evaluated: (1) uninseminated; (2) inseminated‐unfertilized; and (3) fertilized‐uncleaved. All oocytes had undergone germinal vesicle breakdown at the time of retrieval and were salt‐stored (pH 7.2) for not more than 30 days. Sperm binding was recorded under hemizona assay (HZA) conditions using spermatozoa from eight fertile men (HZA control) and from (1) four teratozoospermic (HZA test) and (2) four normozoospermic (HZA test) infertile men. First, the mean numbers (±SD) of sperm tightly bound for fertile controls and teratospermic men to hemizonae from uniseminated oocytes were 69.7 ± 16 and 14.5 ± 7, respectively (P = 0.02). Likewise, hemizonae from uninseminated oocytes bound 102.0 ± 19 and 114.0 ± 28, respectively, for fertile controls and normospermic men (P = 0.5). Second, hemizonae obtained from inseminated‐unfertilized IVF oocytes bound 44.2 ± 12 and 19.7 ± 6 for fertile controls and teratospermic men, respectively (P = 0.02). This category of oocytes bound 100.5 ± 7 and 108.5 ± 11 sperm, respectively, for fertile controls and normospermic semen (P = 0.3). Third, HZA results of fertilized but uncleaved oocytes showed a mean number of tightly bound sperm of 6.0 ± 4 compared with 65.0 ± 1 in control, uniseminated oocytes using fertile sperm. These results demonstrate that uninseminated and inseminated‐unfertilized human oocytes, salt‐stored under controlled pH conditions, give reliable information regarding sperm binding potential under HZA conditions.