GLOBULIN-ENRICHED PROTEIN SUPPLEMENTS SHORTEN THE PRECOMPACTION MITOTIC INTERVAL AND PROMOTE HATCHING OF MURINE EMBRYOS

PROBLEM: To determine whether Synthetic Serum Substitute (SSS), which contains human globulins in addition to Human Serum Albumin (HSA), is superior to HSA alone as a protein supplement for embryo culture. METH OD: Development of mouse zygotes to eight-cell/compacting morulae and to hatching/hatched blastocysts was assessed in Human Tubal Fluid (HTF ) medium containing either SSS or HSA. RESULTS: Although there was no difference in the overall blastocyst rate at 120 h in HTF+SSS versus H TF+HSA, significantly more embryos at 54 h were at the eight-cell/comp acting morula stage in HTF+SSS. At 120 h, there were more hatching/hat ched blastocysts in HTF+SSS, and hatching correlated with SSS concentr ation. Addition of isolated globulins to HSA significantly stimulated the number of hatching/hatched blastocysts. Hatching could be ''rescue d'' by transfer of embryos grown in HTF+HSA to globulin-containing med ia and prevented by removal of globulins as late as the compacted moru la stage (54 h). CONCLUSIONS: SSS is superior to HSA alone for embryo culture. The stimulatory effects on mitosis and hatching may be mediat ed directly by globulins or by other components in the globulin-enrich ed fraction.