EXPRESSION OF SRY TRANSCRIPTS IN PREIMPLANTATION HUMAN EMBRYOS

We have examined the expression of SRY mRNA in individual in vitro fer tilized preimplantation human embryos; because of ethical constraints, these studies were confined to embryos with one and three pronuclei, Using a sensitive reverse transcriptase-polymerase chain reaction (RT- PCR) assay, we observed SRY mRNA at the one-cell through the blastula stages but not in spermatozoa, These results indicate that the de novo transcription of this sex-specific gene occurs at a developmental tim e considerably earlier than that of gonadal differentiation. Our resul ts also indicate that in vitro fertilized embryos with one pronucleus are likely to be diploid. (C) 1995 Wiley-Liss, Inc.