Blastocyst formation and cell numbers in human frozen-thawed embryos following extended culture

Abstract

Background: Blastomere loss following human embryo cryopreservation has been shown to be associated with reduced implantation potential. In order to elucidate the underlying mechanism, the present study was designed to investigate the consequences of blastomere loss on subsequent preimplantation development in vitro. Methods: Cryopreserved embryos destined for disposal were thawed and cultured for 96 h prior to determination of total cell numbers in resultant blastocysts. Results: The proportion of embryos which formed blastocysts in vitro was significantly reduced when blastomere loss was evident in thawed embryos (25 versus 41% in fully intact thawed embryos). In addition, blastocysts from..