Evidence that protease action is not specifically involved in the hatching of rabbit blastocysts caused by commercial bovine serum albumin in culture

Abstract

Commercial samples of bovine serum albumin (BSA) in a complex medium caused growth of 1-cell rabbit embryos to completely hatched blastocysts. Heat treatment of the BSA at 65 or 80.degree. C significantly decreased blastocyst formation and expansion, and destroyed the ability to cause blastocyst hatching. Addition of trypsin at levels down to 20 ng/ml caused the formation of hatched blastocysts which degenerated rapidly. The effects of 5 protease inhibitors (ovomucoid trypsin inhibitor, .alpha.-1-antitrypsin, TAME [N-.alpha.-p-tosyl-L-arginine methylester HCl], TLCK [N-.alpha.-p-tosyl-L-lysine chloromethyl ketone HCl] and soybean) were tested. Ovomucoid trypsin inhibitor, TAME and TLCK significantly inhibited blastocyst hatching but only at the highest concentration used. These inhibitors also reduced blastocyst formation and expansion, indicating that their effect was not specifically on blastocyst hatching in vitro. Hatching of rabbit blastocysts is probably not dependent on protease action.