The purpose of the present study was to investigate the efficiency of embryo cryopreservation for four transgenic (TG) thalassaemic mouse strains, which is a key element of the ongoing gene banking efforts for these highvalue animals. Heterozygous TG embryos were produced by breeding four lines of TG males to wild-type (WT) females (C57BL/6J). Intact two-cell embryos were cryopreserved by vitrification in straws using 35% ethylene glycol. Survival rates of cryopreserved embryos ranged between 91.1% (102/112) and 93.6% (176/188) without significant differences between the lines. In contrast, the paternal line had a significant effect on the development of these embryos to the blastocyst stage, which ranged from 50.6% (92/182) to 77.5% (79/102). This effect was also noted following embryo transfers, with implantation rates varying from 17.3% (19/110) to 78.1% (35/45). The results demonstrate that the in vivo developmental potential is significantly influenced byTG line and reveal a specific line effect on cryosurvival. All bacterial artificial chromosome transgenic fetuses developed from vitrified-warmed embryos showed expression of the human β-globin transgene. In conclusion, the present study shows a strongTG line effect on developmental competence following cryopreservation and the vitrification method was successful to bank the human β-globin TG-expressing mouse strains.
- Embryo banking
- Thalassaemia transgenic