Effect of zona incision by piezo-micromanipulator (ZIP) on in vitro fertilization in 21 transgenic mice lines.

Zona incision using a piezo-micromanipulator (ZIP) has been demonstrated to be effective for in vitro fertilization (IVF) using cryopreserved C57BL/6 spermatozoa. In this study, ZIP oocytes inseminated with frozen-thawed genetically modified C57BL/6J or FVB mice spermatozoa (21 lines) showed fertilization rates of 22-75% and live fetus rates of 8-49%. In 6 of the lines, the fertilization rates for oocytes compared with ZIP (42-75%) were significantly higher than that of nontreated oocytes (0-50%). Using only 90 oocytes for IVF with ZIP, 5 breeding pairs were produced from cryopreserved genetically modified mice spermatozoa. Our results indicate that application of the ZIP technique is effective for IVF using cryopreserved genetically modified mouse spermatozoa.