A CULTURE SYSTEM FOR THE DEVELOPMENT OF THE PREIMPLANTATION RAT EMBRYO

We describe a system for the culture of 1-cell rat embryos through to the blastocyst stage, using co-culture on specific feeder cell layers and particular defined media. We show that the use of rat uterine epit helial cells as a feeder layer, together with either M16M, CZB or HECM -1 media at 38.5 degrees C can improve the in vitro development of cul tured rat embryos. There was considerable variation in the culture con ditions, which were optimal for each strain of rat tested. We show tha t the 4 to 8-cell embryos are viable after reimplantation and that the second 4 to 8-cell block in the rat can be overcome using HECM-1 in a co-culture system, thus enabling the in vitro culture of rat embryos up to the blastocyst stage.