In vitro development of domestic cat embryos following intra-cytoplasmic sperm injection with testicular spermatozoa

The objective was to assess the ability of testicular spermatozoa to fertilize in vitro matured domestic cat oocytes and support blastocyst formation in vitro following intra-cytoplasmic sperm injection (ICSI). After IVM, oocytes were randomly and equally allocated among treatment groups (ICSI with testicular spermatozoa, ICSI with ejaculated spermatozoa, sham ICSI, and control IVF). At 18 h after either injection or insemination, the percentage of fertilized oocytes (per total metaphase 11 oocytes) was similar to 65% after ICSI with testicular or ejaculated spermatozoa (P > 0.05), which was less (P < 0.05) than control IVF (similar to 90%). On Day 7, the percentage of cleaved embryos (per total metaphase 11 oocytes) was similar to 60% after ICSI with testicular or ejaculated spermatozoa (P > 0.05), which also was less (P < 0.05) than control IVF (similar to 85%). After ICSI with testicular spermatozoa, the percentage of blastocysts (per total cleaved embryos) was similar to 11.0%, which was less (P < 0.05) than ICSI with ejaculated spermatozoa (similar to 21.0%); the latter was less (P < 0.05) than control IVF (similar to 43.0%). No blastocyst formation was observed after sham ICSI. For the first time in the domestic cat, this study demonstrated the fertilizing ability and developmental potential of intra-testicular spermatozoa delivered directly into intra-ovarian oocytes matured in vitro. Published by Elsevier Inc.