title: Assessment of the viability and pregnancy potential of mouse embryos biopsied at different preimplantation stages of development.
abstract: The developmental potential in vitro and in vivo of preimplantation mouse embryos biopsied at the 4-cell, 8-cell and morula stages were investigated. Biopsy had the least impact when performed at the 8-cell stage. There was no effect of biopsy on the development of 8-cells of blastocysts in vitro (95% compared with 99% of controls) or the implantation rate after transfers (82 versus 87%, P greater than 0.05); however, fewer embryos (52 versus 71%, P less than 0.05) resulted in viable fetuses. There was no effect of biopsy at the 8-cell stage on fetal weight on day 17. Blastocyst formation in vitro was significantly less for 4-cell biopsies compared with their controls (76 versus 90%, P less than 0.001) and biopsy also affected the implantation rate (44 versus 59%, P less than 0.01). Biopsy was most detrimental when performed on morulae, reducing the implantation rate from 65% for controls to 21% for biopsies (P less than 0.001). Fetal viability was also markedly affected with a reduction on day 17 from 42 to 26% accompanied by a significant reduction (24%, P = 0.02) of the mean fetal weight. Handling of embryos for biopsy at the morula stage, which involved removal of the zona pellucida, was a significant but not complete cause of the reduced implantation potential observed (sham-controls and intact-controls: 34 and 65%, P less than 0.001), while puncture of the zona during the biopsy of 4-cell and 8-cell embryos had no effect. Therefore, the 8-cell mouse embryo is the most suitable state for embryo biopsy.
authors.affiliation: Human Reproduction Unit, Royal North Shore Hospital of Sydney, St Leonards, NSW, Australia.
authors.forename: U B
authors.initials: UB
authors.lastname: Krzyminska
authors.forename: J
authors.initials: J
authors.lastname: Lutjen
authors.forename: C
authors.initials: C
authors.lastname: O'Neill
mesh_terms: D000818:Animals; D001706:Biopsy; D010064:Embryo Implantation; D020964:Embryo Loss; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D047108:Embryonic Development; D005314:Embryonic and Fetal Development; D005260:Female; D051379:Mice; D009028:Morula / Q000502:physiology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*