Births of kittens produced by intracytoplasmic sperm injection of domesticcat oocytes matured in vitro

In Experiment 1, cleavage frequency and in vitro development of domestic ca t embryos produced after in vitro maturation of oocytes obtained from ovari es after ovariohysterectomy (in vitro) with that of oocytes retrieved from follicle-stimulating hormone-treated donors at 24 h after administration of luteinizing hormone (in vivo) and fertilization by intracytoplasmic sperm injection (ICSI) or IVF were compared. In each group presumptive zygotes we re assessed for cleavage on IVC Days 1 and 4 and for development to blastoc ysts on IVC Day 7. In vitro matured oocytes had lower frequencies of meioti c maturation (59.2% v, 66.5%), cleavage at Day 1 (41.4% v. 64.9%) and devel opment to the morula stage at Day 4 (65.8% v. 87.9%) than did in vivo matur ed oocytes, after ICSI and IVF. Development to the blastocyst stage was low er in in vitro matured oocytes (19.0%) than in vivo matured oocytes (29.5%) after ICSI. In Experiment 2, we evaluated the capacity of sperm injected o ocytes without a visible polar body to undergo cleavage and in vitro develo pment. More in vivo matured than in vitro matured oocytes underwent cleavag e at Day 1 (46.6% v. 12.6%) and developed to the morula stage by Day 4 (66. 7% v. 46.1%). but no blastocysts were obtained at Day 7 in either group. In Experiment 3, we evaluated the in vivo viability of domestic cat embryos d erived from ICSI of in vitro matured oocytes. Morula stage embryos were tra nsferred to 18 domestic cat recipients either on Day 4 or 5 after oocyte re covery. A total of 3 domestic cat recipients were pregnant after transfer t o recipients on Day 5. Two pregnant cats delivered two normal and healthy l ive male kittens on Day 68 of gestation and the remaining cat delivered a m ale kitten on Day 62 that died during the last two days of gestation. These results demonstrate that: (1) inadequate cytoplasmic maturation of in vitr o matured domestic cat oocytes is the main cause of deficient oocyte activa tion; (2) the injection of oocytes without a visible polar body is a useful technique to evaluate oocyte cytoplasmic maturation. and (3) blastocysts o btained after ICSI of in vitro matured oocytes are viable and not a result of parthenogenesis.