Tropomyosins (TMs) comprise of a family of actin-binding proteins which play an important role in regulation of contractility in muscle and non-muscle cells.There are four different TM genes (alpha-TM, beta-TM, TM 30 and gamma-TM).It is generally accepted that TM isoforms are related to the cardiac development.However, in the proteomic analysis of the mouse blastocysts,we discovered gamma-TM was related to the blastocyst hatching.To our great interest, we conducted experiments observing expression of gamma-TM during the stages of cleavage, morula,blastocysts and hatching blastocysts using immunofluorescence histochemistry.