EFFECT OF CULTURE IN-VITRO AND ORGAN-CULTURE ON THE DRY MASS OF PREIMPLANTATION MOUSE EMBRYOS

The dry mass of mouse embryos cultured in vitro in medium alone or in an organ culture system were measured by means of the Vickers M86 scan ning microinterferometer. The data were compared with previous data on the dry mass of preimplantation embryos in vivo. The metabolism of em bryos cultured in vitro differs from that of fresh embryos. In culture d embryos, dry mass decreases throughout the 2-cell stage whereas the dry mass is increasing at this stage in vivo. Embryos in an organ cult ure system regain a dry mass profile, similar to that observed in vivo at the late cleavage stage. These results support the view that condi tions for embryo metabolism are suboptimal in vitro and that, although the oviduct may confer some advantage on developing embryos in vitro, it is unable fully to support the pattern of metabolism, as assessed by dry mass, observed in vivo.