Transfer of human sperm into the perivitelline space of human oocytes after zona-drilling or zona-puncture.

To evaluate the transfer of sperm from severely oligozoospermic men into the perivitelline space of mature oocytes, zona-drilling with acid phosphate-buffered saline (PBS) and direct zona-puncture in the presence of cytochalasin D were studied. Zona-drilling also was done for eggs from patients with previous failed in vitro fertilization (IVF). Forty-seven eggs from seven patients with oligozoospermia and three patients with failed IVF had a mean of between 2.6 and 3.6 sperm transferred into the perivitelline space. In the group whose eggs had zona-drilling with acid PBS, 1 of 13 eggs fertilized from the oligozoospermic category, while there was no fertilization from the failed IVF category. Karyotyping of the unfertilized eggs after zona-drilling revealed a high incidence (2/5 and 3/7, respectively) of possible arrest at anaphase II after reinitiation of meiosis. In the group whose eggs were directly punctured through the zona in the presence of cytochalasin D, there was no fertilization in 23 undamaged eggs. Two of the 15 interpretable karyotypes were aneuploid, but this incidence is within that observed for our unfertilized eggs after IVF. Hence, the use of acid PBS for zona-drilling is not advised. Moreover, transfer of sperm from men with previous failed fertilization resulted in poor fertilization rates.