Use of mouse oocytes to evaluate the ability of human sperm to activate oocytes after failure of activation by intracytoplasmic sperm injection.

The objective of the present study was to investigate the nuclei of human sperms that failed to fertilize human oocytes after intracytoplasmic sperm injection (ICSI). The sperms were injected into mouse oocytes by a piezo-micromanipulator, and some of these oocytes were artificially activated with strontium chloride (SrCl2) after ICSI. The oocytes were fixed, stained, and subjected to chromosomal analysis. The survival rate of mouse oocytes injected with infertile human sperms was 92.0% (46/50), while that of the control mouse oocytes injected with fertile human sperms was 73.6% (81/110). The rate of two pronuclei (2PN) formation was 0 (0/46) by the infertile sperms and 81.5% (66/81) by the fertile ones, a significant difference (p < 0.01). Sperm chromosomes in non-activated oocytes were present as premature chromosome condensation (PCC). Artificial activation after ICSI increased the 2PN formation rate in the infertile group to 90.3% (28/31). The results of the present study suggest that infertile sperms have a low potential to spontaneously activate oocytes and to form pronuclei. Thus, artificial activation after ICSI may rescue oocytes fertilized with infertile human sperms that do not produce 2PN. The present study proved the usefulness of mouse oocytes as specimens in evaluating the oocyte-activating capacity of objective human sperms prior to ICSI treatment.

Pregnancy following chemical activation of oocytes in a couple with repeated failure of fertilization using ICSI: case report.

We report our attempts to achieve a successful pregnancy outcome with calcium ionophore A23187 and puromycin oocyte activation using sperm from a normozoospermic husband of a patient with previous repeated failed fertilization following ICSI. Oocytes from the female partner of a couple with a 4 year history of unexplained primary infertility with repeated failed fertilization following ICSI were used. In the latest ICSI attempt, oocytes were activated by treatment with calcium ionophore (5 min) and puromycin (5 h), then cultured. In this cycle, assisted oocyte activation with calcium ionophore and puromycin after ICSI resulted in a satisfactory fertilization rate (8/12; 66.7%); in prior cycles only one of 71 oocytes (1.4%) was fertilized. The outcome was a Caesarean section delivery of a healthy male infant without congenital abnormalities at 41 weeks, 2 days of gestation. In conclusion, the use of calcium ionophore and puromycin for oocyte activation was found to be a useful method in a case of repeated failed fertilization after ICSI.