Intracytoplasmic injection of human sperm into the hamster oocyte (hamster ICSI assay) as a test for fertilizing capacity of the severe male-factor sperm.

Abstract

Our objective was to investigate the fertilizing ability of human sperm from severe male-factor patients, by microinjection of single sperm into the hamster oocyte. Semen samples of severe male factor either with a 0% penetration rate in the zona-free hamster test or with a very low number of motile sperm for which performing the standard penetration test was impossible were used. For the control study, oligozoospermic semen samples with at least 10% penetration rate in zona free hamster test were used. All materials were collected from the National University Hospital, Singapore. There were 10 patients in both the experimental and the control groups. Intracytoplasmic sperm injection (ICSI) was carried out. The main outcome measures were sperm head decondensation and pronuclear formation. Twenty-one percent of the injected sperm could decondense and undergo male pronuclear formation. This rate was not significantly different from that in the control study group (28%; P = 0.13). A small proportion of the oocytes was damaged during the procedure (9.2 and 8.75% in experimental and control groups, respectively). Hamster-ICSI assay may be of benefit in predicting the sperm's ability for further development before allowing the patient to undergo the clinical program.