EMBRYO-TRANSFER IN MOUSE - INFLUENCE OF G ENOTYPE AND OTHER FACTORS

Mice of different lines, with or without superovulation were used as d onors or recipients for embryo transfer experiments. The influence of different parameters was investigated: Number of plug-positive animals after pairing, embryo recovery at days 1 and 4 p.c., transfer of embr yos (untreated and after injection) into the oviducts or uteri of preg nant or pseudopregnant recipients, as well as transfer into the uterus of in vitro cultured embryos. The birth rates after uterine transfer ranged from 27.5% (controls) and 15.3% (for embryos which were injecte d with liposomes). Embryos from the NMRI female x C57Bl male crossing were more vital than embryos from the C57Bl 9 x NMRI male crossing, wh en transferred into NMRI-recipients, although the survival rates of th e in vitro culture were inversed. Embryos from superovulated donors ga ve lower birth rates than those from untreated. Transfer of in vitro d eveloped injected C57Bl zygotes (injected) gave lower birth rates (10. 1%) than those which were immediately transferred into the oviduct. Bi rth rates after transfer into pseudopregnant recipients (oviduct) were 16.7% for embryos injected with DNA and 30.3% for controls, and after transfer in pregnant animals 18.5% and 40.8%, respectively.