Effect of cigarette smoke and alpha-tocopherol (vitamin E) on fertilization, cleavage, and embryo development rates in mice: an experimental in vitro fertilization mice model study.

ABSTRACT

OBJECTIVE: The objective was to elucidate the effects of cigarette smoke per se or vitamin E on mice exposed to cigarette smoke, with regard to fertility and cleavage rates, and embryo development in an experimental in vitro fertilization (IVF) mice model. STUDY DESIGN: Female and male mice, weighing 18-25 g and aged 14-16 weeks, were separated and divided into cigarette smoke-exposed (SE) and non-smoke-exposed (NSE) groups. A specially designed cage with a cigarette smoking machine was constructed. The SE (20 cigarettes/day) group was put in the cage for 10 weeks. SE and NSE female and male mice were given 50mg/kg of vitamin E intraperitoneally for 10 weeks and were cross-mated thereafter so as to produce seven different subgroups of mice population as follows group I-NSE male and female mice (control); group II-SE female mice and NSE male mice; group III-NSE female with SE male mice; group IV-SE male and SE female mice; group V-SE female mice treated with vitamin E and SE only male mice; group VI-SE only female and male mice treated with vitamin E; and finally group VII-vitamin E-treated SE male and female mice. Following superovulation with FSH, follicles of female mice were obtained via laparotomy under high-dose ether. Male mice testicles were retrieved via the same surgical procedure. Both gametes were obtained and used for IVF. Fertilization, cleavage rates, and day 3 embryo grading were assessed in four groups. RESULTS: With regard to fertilization rate, group II (36%) significantly differed from group I (85%, p=0.002), group III (68.7%, p=0.04), but not from group IV (20.6%, p=0.34). Taking embryo development rate into consideration, group II (32%) had a lower percentage of embryo development compared with group I (75%, p<0.01) and group III (62.5%, p<0.001), but not group IV (17.2%, p=0.42). Percentages of embryo cleavage, embryo development, and day 3 grade I embryos did differ among four of the groups (p>0.05). CONCLUSIONS: Fertilization and cleavage rates were mainly affected in the SE female mice population. The impact of vitamin E on fertilization, cleavage, and embryo development rates was not relevant among SE male and SE female mice.