EFFECT OF EXTRACELLULAR K-VITRO( ON HATCHING AND OUTGROWTH OF MOUSE BLASTOCYSTS IN)

The dependence of blastocyst development on the extracellular Na+/K+ r atio was investigated in an in vitro system. Hatching and outgrowth of mouse blastocysts was enhanced at Na+/K+ ratios between 3 and 10 comp ared to the ratio of about 25 typical for most culture media and serum . At a Na+/K+ ratio of 2, blastocyst hatching and outgrowth were inhib ited. The requirement of blastocyst development for relatively high ex tracellular K+ concentrations agrees with the fact that K+ concentrati ons in oviduct and uterine secretions are higher than in serum. The fi ndings can also be relevant in optimizing in vitro culturing technique s for blastocysts.