Parthenogenetic activation of marmoset (Callithrix jacchus) oocytes and the development of marmoset parthenogenones in vitro and in vivo

Mammalian oocytes can be induced to resume meiosis without fertilization, a nd the resulting parthenogenetic embryos carry only maternal chromosomes. H uman oocytes can be activated by many chemical and physical stimuli, but po stimplantation studies of human parthenogenetic embryos are not ethically a cceptable. The common marmoset monkey (Callithrix jacchus) is a good model for studying primate parthenogenetic development postimplantation, since fo llicular aspiration, embryo transfer, and early postimplantation developmen t of biparental embryos have already been described. Marmoset oocytes were either subjected to two series of six electrical puls es (DC; 2 kV/cm and 70 mu sec) or were incubated in 7% ethanol in PBS. Nine ty-two percent (68 of 74) and 20% (8 of 40) of marmoset oocytes were activa ted by electrical stimulus or ethanol, respectively. Parthenogenetic (n = 3 ) or in vitro-fertilized (n = 2) embryos were transferred at the 4-cell sta ge to synchronized recipient female marmosets (n = 5). Progesterone, chorio nic gonadotropin, and inhibin in the peripheral plasma of recipient animals were measured. After 33 days of gestation, recipient animals were perfused and the uteri were collected. The 2 females that had received biparental e mbryos and 2 of the 3 females that had received parthenogenetic embryos dis played biochemical and histological evidence of implantation. This is the first report that a primate embryo comprising only parthenogene tic cells is capable of implantation. This highlights the need to scrutiniz e levels of parthenogenesis associated with human assisted reproductive tec hnologies. Marmoset parthenogenones also provide a unique model for elucida ting the roles of parental genomes in primate development.