Developmental precocity in transferred mouse embryos influencing the teratogen response to salicylate

Asynchronous blastocyst transfer, supposed to equalize the developmental stage of native and alien embryos during the organogenic period, was used as a tool in a teratological investigation. A spurious protection by the transfer as such was shown to depend on a persisting asynchrony between native and alien foetuses. The initial difference of 24 h was not nullified, but decreased to 8 h. This difference allowed transferred foetuses to pass the period of maximum sensitivity before salicylate treatment.