Purpose: Subzonal sperm insemination (SUZI) into hamster oocytes was performed to establish the karyotypes of the fertilizing spermatozoa.
Methods: Spermatozoa from two males with normal semen parameters were microinjected. Of 72 (52 + 20) analyzed sperm chromosome metaphases, only 1 (1.4%) was considered abnormal, showing a structural abnormality.
Results: No hyperhaploidy was observed. Rates of sperm chromosomal abnormalities after microinjection were not higher than those reported previously using zona-free egg insemination, suggesting that the SUZI procedure per se does not increase sperm chromosomal abnormalities.
Conclusions: The use of subzonal insemination into hamster oocytes for the study of human sperm chromosomes in males with low sperm counts is discussed.