Normal postimplantation development of mouse parthenogenetic embryos to the forelimb bud stage

Abstract

PRE- AND POSTIMPLANTATION development of parthenogenetic embryos is of interest in analyses of the role of the male genome in early mammalian development, differentiation, and in haploid and diploid gene expression in embryogenesis. Diploid and haploid mouse parthenogenones evidently possess the capacity to form teratomas and give rise to differentiated tissues^1,2 although normal organogenesis has not been observed to progress beyond the early somite stage in utero³. Birth of live parthenogenetic rabbits has been reported^4–8, and Beatty⁹ has estimated that 1 in 200 embryos induced under similar conditions can be expected to reach term. There is, however, some doubt about the validity of this early work since subsequent attempts to repeat it have failed to obtain development beyond the blastocyst stage^10,11. Mouse parthenogenones develop to the egg cylinder stage but only one 8-somite embryo has so far been obtained^3,12. We have examined the postimplantation development of diploid mouse parthenogenones and report that a high proportion progressed to somite embryos when blastocysts were transferred to pseudopregnant recipients. Recipients were ovariectomised following embryo transfer and their pregnant state maintained with exogenous hormones. Two apparently normal forelimb-bud stage embryos with a beating heart and yolk sac circulation were obtained. Other embryos isolated from the same recipient showed disorganised development, and a twin conceptus was obtained from a further recipient.